www.planetearth.nerc.ac.uk
Autumn 2010
Jobs for the
buoys
The impact of impacts
n
Where is North?
n
Tracking our ancestors
n
The carbon age
Contents
Planet Earth
Autumn 2010
FEATURES
10 The impact of impacts
Could sulphide deposits help find life on Mars?
30 Mysteries of the blue ocean
Not a watery desert after all.
12 Current thinking
32 Website rocks
Geology for the people.
Fine-tuning ocean observations.
14 Agave – biofuel of the future?
New energy crops for arid climates.
16 Where is North?
Tracking the shifts in the Earth’s magnetic field.
18 Reading nature’s barcode
River sediments and climate history.
20 The carbon age
How a new, portable sensor is shedding light
on the carbon cycle.
16
22 COVER STORY
Jobs for the buoys
New tools to monitor the English Channel.
24 Tracking our ancestors
Fossil footprints reveal how we evolved.
26 Hot off the press
Hands-on geologists make miniature planets.
28 When politics and science come
face to face
From Ethiopian volcanoes to Westminster.
NERC scientists: we want to hear from you
Planet Earth is always looking for interesting NERC-funded science for articles and news stories. If
you want to see your research in the magazine, contact the editors to discuss. Please don’t send in
unsolicited articles as we can’t promise to publish them. We look forward to hearing from you.
Planet Earth is the quarterly magazine of the Natural Environment Research Council. It aims to
interest a broad readership in the work of NERC. It describes new research programmes, work in
progress and completed projects funded by NERC or carried out by NERC staff. Some of this work
may not yet have been peer-reviewed. The views expressed in the articles are those of the authors
and not necessarily those of NERC unless explicitly stated. Let us know what you think about Planet
Earth. Contact the editors for details.
Front cover: Autonomous buoy, see page 22.
24
30
Editors: Adele Rackley, 01793 411604, [email protected]
Tom Marshall, 01793 442593, [email protected]
Science writer: Tamera Jones, 01793 411561, [email protected]
Design and production: Candy Sorrell, [email protected]
Available as an e-magazine at:
www.nerc.ac.uk/publications/planetearth/
ISSN: 1479-2605
THE CONSEQUENCES OF CLIMATEGATE
The consequences of
Climategate
T
he reviews of the Climategate
affair, which centred on
emails taken from the
University of East Anglia’s
Climate Research Unit (CRU),
have submitted their findings, and
enough time has passed that we can
reflect on these events and what we
should learn from them.
It’s worth pointing out that all
three inquiries have exonerated
CRU researchers of any serious
misconduct. There were problems
with working practices at the
CRU, but its scientists’ professional
integrity was fully confirmed and
the inquiries found no evidence
of research being manipulated
to support the idea that human
activities are changing the climate.
It’s clear that the supposed
scandal got much more attention
from the media than the conclusions
of the independent reviews. Some
members of the public who haven’t
followed the story closely may have
been left with the impression of
serious wrongdoing where there was none.
There is no doubt the affair has
reduced public trust in climate
science and climate scientists. It’s
important that scientists regain this
trust. In part this will involve trying
harder to communicate what we do
more clearly. But we also need to
be more willing to engage in debate
with critics, and to demand that the
so-called sceptics make it clear what
credible, published evidence they
have to back up their assertions –
usually there is little or none.
Too often, researchers have left
the sceptics’ claims unchallenged,
and this has made it seem that there
is genuine doubt over whether or
not the climate is changing, and
that scientists have no answers to
the charges made against them.
Some of these reflect
misconceptions about what science
is like. Research involves a huge
amount of challenge from peers;
it is not a cosy club – more like
a bear pit. The climate scientists
themselves are sceptics. By
contrast, many self-proclaimed
sceptics seem willing to accept
anything they read that downplays
the evidence of human-induced
climate change or casts climate
science in a bad light, no matter
how thin the evidence for it is.
The fact that this material
nevertheless gets spread so widely
is largely due to the vast number
of blogs and other websites now
covering the subject. We know
the blogosphere will continue to
exist and be influential, and in
many ways this surge of interest
in climate science is a healthy
development. But not all claims are
equally credible.
Without professional quality
control we can have no basis for
establishing new knowledge – and,
yes, professional here means other
trained scientists. Some people
have challenged the principle of
peer review, in which new research
is evaluated by other scientists
with expertise in the same field.
They argue it leads to group-think
and the suppression of dissenting
views. But the peer-review process
is at the heart of how we test the
credibility of new science. It is also
central to how research councils
decide what to fund. Without it,
society has no way of telling good
science from bad.
The problem, again, is trust –
people have to be confident in the
scientists doing the peer reviewing.
One way of rebuilding this trust
is for researchers to do more to
engage the public with their work.
Alan Thorpe Chief Executive, NERC
Taxpayers pay for most of the
science NERC funds, so they have
a stake in the results and we have
a duty to communicate the science
in an accessible way at all stages in the process.
Scientific data should be openly
available, after the researchers have
had a reasonable period – normally
two years from the end of data
collection – in which to examine
their results and draw inferences.
NERC runs several data centres
ensuing media debate. For example,
it was not emphasised that the
CRU data is only a small part of
climate science, albeit an important
one, and that no mistakes had
been found in the published work
based on it. This made it easy for
the opponents of global warming
to blow the CRU emails out of all
proportion and portray all climate
science as flawed.
The media’s default option
still seems to be a one-on-one
Research involves a huge amount of
challenge from peers; it is not a cosy
club – more like a bear pit.
where we require our researchers to
place their data for general access.
We are doing more than ever to get
the scientists whose work we fund
to think harder about how that
work will benefit society as a whole.
And we are making unprecedented
efforts to involve the public in our
science from the start through
dialogue to inform the research
process.
It’s also vital that scientists
get better at dealing with the
media. Journalists said the science
community went silent when
Climategate broke. Maybe so, but
perhaps this was partly because
scientists saw at once that the story
wasn’t really about science at all,
but about particular scientists and
how they conducted their research.
Many in the research community
didn’t feel comfortable commenting
on that.
This may be understandable,
but unfortunately it meant that
vital points were missing from the
confrontation between scientist and
sceptic, as if the evidence for both
positions was similar in quantity
and quality. And too often, the
same few scientists are asked for
interviews again and again; it would
be better if the public could see
the true diversity of the research
community. Scientists must do
more to communicate the fact that
research is a human activity subject
to human emotions and failings.
They also need to get better at
putting their points across in plain,
succinct English.
These changes are badly needed,
because we have much further
work to do to communicate the
complexities and uncertainties
of climate science. Climategate
has been a difficult experience for
many in the field, but perhaps
if it helps bring about changes
in areas like these, the affair
may turn out to have served
a useful purpose after all.
Planet Earth Autumn 2010
1
DAILY UPDATED NEWS www.planetearth.nerc.ac.uk
News
Chemicals make young
burying beetles beg
for food
It’s not just birds that respond
to the begging cries of their
offspring. Burying beetles do too.
But burying beetle larvae grow
up in complete darkness and can’t
see their parents – so how do they
know when to beg?
It turns out they are responding
to chemicals on the mother’s body.
Burying beetles are so named
because they lay their eggs in the
soil near the carcass of a small bird
or mammal which they’ve buried
to provide food for their larvae.
But sometimes this rotting
flesh isn’t enough for the hungry
larvae, which beg their parents for
regurgitated carrion.
‘We wanted to understand what
the costs of begging to burying
beetle larvae were. To do this,
we had to stimulate begging,’
explains Dr Per Smiseth from the
University of Edinburgh, who
led the research, published in
Behavioral Ecology.
When they put a dead burying
beetle parent next to its offspring,
they were surprised to see the
larvae begged for hours. They
2 Planet Earth Autumn 2010
couldn’t have been relying on
behavioural cues, which led the
researchers to think the trigger
may be chemical.
‘In the same beetle, there’s some
evidence that females discriminate
between their male partner and
intruders because of differences in
the hydrocarbons in the insects’
cuticles,’ says Smiseth.
So the researchers washed some
female parents in a solvent to strip
the hydrocarbons away and found
that larvae begged less towards
these washed parents than toward
unwashed females.
‘We’re not sure at the moment
exactly what the chemical
is, but we think it’s probably
hydrocarbon,’ says Smiseth.
The researchers are keen to take
their work further. ‘We want to
see if there’s a difference between
males and females. Females are
the primary care-givers, but larvae
might respond to males in the
same way they respond to females.
We just don’t know right now,’
adds Smiseth.
Kinder Eggs throw light
on mongoose traditions
Scientists have shown for
the first time that wild banded
mongooses pass foraging
traditions down to the next
generation.
Individual mongoose pups
learn one of two different
foraging techniques from an
older relative, called an escort.
Once pups learn a technique,
they stick to it throughout their
lives, say the researchers.
There’s growing evidence
to show that culture is not
exclusively human. For example,
chimps use twigs to fish for ants
and orangutans use sponges to
soak up water.
But until now there’s been
no evidence to show that these
methods are passed on to the
next generation through cultural
transmission.
‘You need experiments to
see how the techniques are
passed on,’ explains Dr Corsin
Müller. He was a member of the
University of Exeter when he
authored the research, published
in Current Biology, but is now at
the University of Vienna.
While studying wild banded
mongooses in Queen Elizabeth
Natural Park, Uganda, Müller
noticed that mongooses use one
of two techniques to crack foods
with a hard shell. They either use their teeth or hurl them at a
hard surface.
To test whether techniques
would be passed on to pups,
Müller filled Kinder Egg plastic
containers with rice and fish.
With no pups around, the
scientists gave adult mongooses
the filled Kinder Egg and
saw that some used the biting
technique to open it and some
used the throwing technique.
Others used both.
Then the researchers allowed
the pups to watch their escorts
open the Kinder Egg.
When the pups had reached
juvenile age, Müller and his team
tested their responses to a filled
Kinder Egg and found that the
young mongooses copied the
technique they saw their escorts
use. And they continued to use
this technique as adults.
‘What’s interesting is that
when people think about
traditions, they usually think
about one population showing
one type of behaviour. But what
we’ve shown is that there are two
behavioural variants in the same
group,’ says Müller.
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News
Signs of asteroid
impact turn out
to be fungus
Tiny black spheres, previously
seen as evidence that a catastrophic
asteroid impact caused a little ice
age, are actually charred fungus,
according to new research.
So ideas about what caused
the Younger Dryas stadial, a cold
period which began around 12,900
years ago, need to be revised.
The impact theory was partly
based on the discovery of carbon
‘spherules’, tiny black spheres up
to a millimetre across that were
found in sediment layers deposited
around this time. Researchers have
argued that these formed in the
intense heat of wildfires triggered
when a comet or asteroid either
hit the Earth or exploded in its
atmosphere.
These fires supposedly raged
across vast areas, stretching from
coastal California across North
America to Europe. The idea was
that only these continent-wide
infernos could have created carbon
spherules in such numbers, and
only an asteroid impact could have
ignited such a conflagration.
But a recent paper in Geophysical
Research Letters suggests that
the spherules are really just
fungal sclerotia – compact balls
of hardened tissue produced by
certain fungi. These are common
worldwide, in both modern and
ancient soils.
The 12,900-year-old spherules,
found in Californian sediment
samples, have indeed been
blackened by fire. But through
experiments in the lab the research
team showed that they had only
been exposed to comparatively low
temperatures.
The reflectivity of the spherules’
glossy black surface suggests they
couldn’t have been higher than
around 450°C. A continent-wide
conflagration would almost
certainly be far hotter – perhaps
800°C – and would have destroyed
the sclerotia or at least burned out
their distinctive honeycomb-like
internal structure.
‘They are clearly fungal from
their morphology,’ comments
Professor Andrew C Scott, a
palaeobotanist at Royal Holloway,
University of London, lead author
of the paper.
Warmer climate
may have wiped
out the cave lion
Cave lions probably became
extinct across Europe and Asia
14,000 years ago because a warmer
climate drastically reduced the
availability of their favourite
hunting grounds.
As the climate warmed around
14,700 years ago, forests and
shrubs steadily replaced the open,
steppe-like environment that had
dominated for thousands of years,
reducing the amount of clear space
for the lion to hunt in.
The cave lion roamed the plains
of Europe, northern Asia and
Alaska and north-west Canada
from around 60,000 years ago
until about 14,000 years ago.
From the numerous fossils dated
from the same period, scientists
know that the lion’s preferred prey
were probably bison, reindeer,
horse, giant deer and musk ox.
Before this research, many
scientists thought the cave lion
(Panthera spelaea) may have died
out because it slowly ran out of
food after its prey went extinct.
‘We’ve pretty much ruled this
out now,’ explains Professor Tony
Stuart from Durham University,
who led the research.
Most of the cave lion’s likely
prey survived for thousands of
years after the cave lion went
extinct.
Stuart and his colleague
Professor Adrian Lister from
London’s Natural History
Museum report in Quaternary
Science Reviews how they compiled
111 carbon dates of cave lion bones
or teeth from museums in Europe,
Russia and North America.
Their results suggest the cave
lion went extinct around about
the same time across Europe and
northern Asia. The most recent
date came from a cave lion skeleton
found in France which died about
14,141 years ago.
They found the youngest bones,
from Alaska and the Yukon region,
dated back to 13,300 and 13,800
years ago.
Other researchers have argued
that the arrival of humans on
the cave lion’s patch may have
contributed to its extinction, but
so far there’s no strong evidence
for this.
‘What is clear is that as the
climate changed the environment,
this had a big effect on everything,’
says Stuart.
Earth’s oldest
mantle
discovered
Scientists have found rocks
formed from what they think may
be Earth’s oldest mantle reservoir
– a 4.5-billion-year-old remnant
of the primordial material that
made up the planet not long after
it condensed out of clouds of space
dust.
The discovery, published in
Nature, has important implications
for our understanding of the
Earth’s early history.
‘This is such an exciting
discovery, because this mantle
reservoir could well be parental
to all of the mantle reservoirs we
recognise today in volcanic rocks
around the world,’ says Dr Pamela
Kempton, one of the paper’s
authors who analysed some of the
rock samples while at the NERC
Isotope Geosciences Laboratory in
Keyworth. She has since moved to
become Head of Research at the
Natural Environment Research
Council.
The 60-million-year-old rocks,
found on Baffin Island and West
Greenland in the Canadian Arctic,
preserve the chemical signature of
the mantle reservoir deep within
the Earth from which they formed.
How this remnant of primordial
mantle has persisted since the
planet formed is a mystery, but
one possibility is that the reservoir
is kept isolated at the centre of an
eddy in the mantle, like the still air
in the eye of a very slow hurricane.
The research also suggests
the Earth may have started to
take on its present form earlier
than previously thought. The
rocks have higher ratios of the
element neodymium (Nd) than
chondrites – stony meteorites that
are believed to represent the same
kind of material the Earth formed
out of. These higher ratios were
produced by the radioactive decay
of an isotope of samarium that
became extinct within a couple
of hundred million years after the
Earth formed, so this difference
must have arisen very early in the
planet’s history.
This could mean that the
assumption that the Earth formed
out of similar stuff to chondritic
meteorites is wrong – meaning
we need to rethink large areas of
geology.
Or, it could mean that the Earth
began to differentiate – to change
from a mass of primordial matter
into a more structured form with
crust, mantle and core – very early
in its history.
The creation of a crust and core
would have depleted the mantle
of certain elements. This is the
explanation the researchers favour.
If we assume the early Earth began
this irreversible differentiation
within the first hundred million
years or so of its life, we can
explain the discrepancy between
chondrites and today’s mantle.
Planet Earth Autumn 2010
3
DAILY UPDATED NEWS www.planetearth.nerc.ac.uk
News
Most detailed map of Earth’s gravity revealed
ESA - GOCE High Level Processing Facility
In June scientists unveiled
the most detailed map yet of
the Earth’s gravity, using data
generated by the European Space
Agency’s GOCE satellite, launched
in March 2009.
GOCE stands for Gravity field
and Ocean Circulation Explorer.
The satellite flies in the edge of
the Earth’s atmosphere at a height
of 254.9km and measures tiny
differences in gravity at many
points around the Earth.
The map shows the Earth’s
‘geoid’ – or which parts of our
planet have a greater gravitational
pull than others because of the
different rocks they’re made of.
If you turned this map into a
globe, it would look like a partially
blown-up football, with peaks
representing strong gravity and
troughs showing weaker gravity.
But if you placed a much smaller
ball anywhere on this squashy
football, it wouldn’t move – even if it was on a slope – because
gravity would be exactly the same
all over it.
Because the Earth is the shape of
a squashed ball, gravity is stronger
at the poles than at the equator.
Before GOCE was launched,
scientists knew that gravity is
stronger around Greenland than
around the Indian Ocean for
example.
But ‘the current geoid models
are largely based on ground
measurements, which of course
is difficult in inaccessible parts of
the planet,’ says Dr Helen Snaith
from the National Oceanography
Centre in Southampton.
So the new map is telling
scientists much more about places
where it’s difficult to do ground
research, like the Himalayas, the
Andes and Antarctica.
The geoid model that GOCE
has generated also represents the
shape the world’s seas would be
if there were no winds, tides or
currents. This means scientists
can subtract the geoid from real
measurements of sea-surface height
to work out how winds, tides and
currents affect ocean circulation.
‘Until now, the best maps
we had were on the 400 to 500
kilometre scale. GOCE’s resolution
is focused down to 150 kilometres.
Most ocean currents are around
this width or smaller, so we’re
going to get a lot more detail about
currents with this map,’ explains
Snaith.
Plastics found in the seas around Antarctica
Man-made plastics have
found their way to the most
remote and inaccessible waters
in the world off the coast of
Antarctica.
The seas around continental
Antarctica are the last place on
Earth scientists have looked for
plastic, mainly because they’re
so difficult to get to.
‘We were going to the
Amundsen Sea onboard the
RRS James Clark Ross to collect
biological specimens for the first
time ever, and were well placed
to look for plastics at the same
time,’ explains David Barnes
from the British Antarctic
4 Planet Earth Autumn 2010
Survey, who led the research.
Barnes linked up with other
researchers, from Greenpeace’s
MV Esperanza and ice patrol vessel
HMS Endurance, to look for one of
the most abundant and persistent
scourges of the global ocean –
floating debris. They found that
plastic rubbish was most common
compared with debris made from
metal, rubber or glass.
They report in Marine
Environmental Research how they
found fishing buoys and a plastic
cup in the Durmont D’Urville
and Davis seas of east Antarctica,
and fishing buoys and plastic
packaging from the Amundsen Sea
in western Antarctica.
They found no evidence of
natural debris like branches, shells
or plants.
There are no scientific research
stations or other bases anywhere
near the Amundsen Sea,
suggesting the plastic debris must
have got there via ocean currents.
The researchers also sampled
seabed sediments around
Antarctica for minute degraded
plastics.
Plastic fragments have found
their way as far as South Georgia
in the South Atlantic, so the
researchers were surprised to find
no evidence of fragments in seabed
sediments around the continent.
‘The possibility of tiny pieces
of plastic reaching the seafloor
is especially worrying, because
the continental shelves around
Antarctica are dominated by
suspension feeders, which are
essentially at the bottom of the
food chain,’ says Barnes.
‘But what’s really worrying
about plastics getting to
Antarctica, apart from aesthetics,
is the fact that they can carry
non-native animals. We don’t
have this problem in Antarctica
yet, but with warming seas, they
stand a much better chance of
surviving,’ he adds.
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Birds strengthen
social bonds when
they sense trouble
Maori warriors use the haka
to bond before battle. Now it
seems that birds also demonstrate
bonding behaviour when they
think they might have trouble with
the neighbours.
Scientists know that social birds
become closer immediately after
conflict with other groups, but
until now little was known about
how the risk of future conflict
influenced animal behaviour.
Dr Andy Radford of the
University of Bristol studied
green woodhoopoes to see if they
acted differently when faced with
possible territorial conflict.
These birds live in small groups
in permanent territories; conflict
between groups is frequent close
to territorial boundaries, and
allopreening – when one bird
preens another – is an important
part of group behaviour. The
groups typically consisted of a
dominant breeding pair and up to
six subordinate ‘helpers’.
Radford watched the birds in
the river valleys of the Eastern
Cape Province, South Africa. He
noted the length of periods of selfpreening and allopreening, which
individuals in the group were
involved, and where in the territory
the birds were when the preening
took place.
His results, published in
Biology Letters, show that both the
frequency of allopreening within
the group, and the amount of time
the birds spent doing it, increased
when the group was at the edge of
its territory, where conflict with
neighbouring groups is likelier.
Radford found the biggest
increase was in the amount of
preening given by the dominant
birds to the helpers in the group.
This ‘affiliative’ behaviour is
likely to reassure subordinates
Chris van Rooyen
and increase closeness within the
group, ensuring the birds all stick
together if battle ensues.
Surprisingly, when this
behaviour was observed there had
been no visual or vocal evidence of
other woodhoopoe groups for at
least an hour. This suggests that,
rather than bonding in response
to an immediate threat, the birds’
behaviour was in anticipation of a
possible future threat.
‘It would be wrong to say this
behaviour is firm evidence for
forward planning in birds,’ says
Radford, ‘but it is very exciting
to have seen this link between
potential intergroup conflict and
current intragroup behaviour in
the wild.’
Unique social structures
could explain the
menopause
Human females aren’t
the only ones to go through
menopause – some whale
species also go through a
similar ‘change’, and the unique
structure of human and whale
societies might be responsible,
say scientists.
Short-finned pilot whales
stop breeding when they get to
around 36 years, but can live
until they’re 65. Killer whales
stop having young when they
reach about 48 years of age, but
often live up to 90 years.
This is in line with the socalled grandmother hypothesis,
which suggests that by stopping
having children early and then
helping their existing offspring
survive and reproduce, women
still benefit by helping to pass on
their genes.
Among our ancestors, a
woman would move to wherever
her mate lived. Initially she’d
be completely unrelated to
members of her new ‘group’,
and so would have no incentive
to help them reproduce. But by
having children, as she aged, she
became more related to them.
Then it made evolutionary
sense to stop having children
and help her younger relatives
bring up their children.
Among mammals, however,
it’s unusual for the female to
move away from the family
she was born into – it’s usually
the male that leaves his family
group.
Mammals with this type
of social structure don’t go
through a menopause, but
continue breeding until they die.
Elephants, for example, breed
well into their sixties.
‘We were puzzled by this and
wanted to understand why you
don’t get grandmothers in other
long-lived cooperative species,’
says Dr Rufus Johnstone from
the University of Cambridge,
lead author of the research,
which is published in the
Proceedings of the Royal Society B.
Johnstone and his colleague
Dr Michael Cant from the
University of Exeter describe
how they applied a model
of relatedness – or kinship
dynamics – to the two species
of whale which go through
menopause. They found a
similar pattern of increased
relatedness with age to the one
seen in humans.
In killer and pilot whale
societies both males and females
stay with their family groups,
but males leave temporarily to
mate with females from other
family groups, called pods.
This means that females are
born into a pod which doesn’t
contain their father. But as they
get older and have young of
their own they become more
related to other pod members.
So it makes sense for older
female pilot and killer whales to
stop breeding and instead help
the younger members of their
families raise their offspring.
‘This helps explain why of
all the long-lived mammals,
menopause has only evolved in
humans and toothed whales,’
says Johnstone.
‘It would be good to look into
the social structures of whale
species we don’t know much
about to see how well our theory
stacks up,’ he adds.
Planet Earth Autumn 2010
5
DAILY UPDATED NEWS www.planetearth.nerc.ac.uk
News
Ocean circulation is a
key factor in deglaciation
Most scientists think that
fluctuations in ocean circulation
are linked to changes in climate.
Now they’ve found evidence
linking those fluctuations to
temperature increases so extreme
they can end an ice age.
The Atlantic Meridional
Overturning Circulation
(AMOC) carries tropical surface
waters northwards, and brings
cold, North Atlantic deep water
(NADW) southwards to mix with
deep waters originating in the
Antarctic. When ocean circulation
is strong, heat is moved efficiently
from the tropics to the poles.
When circulation is weak the poles
become colder.
Scientists think that during
particularly cold periods in the last
ice age (so-called Heinrich Stadial
events) the AMOC weakened
significantly. A stronger AMOC is
associated with warmer phases.
A team of researchers, led by
Dr Stephen Barker from Cardiff
University, believe the link is so
strong that deglaciation may only
happen when the AMOC shifts
from weak to strong.
Models predict that when the
AMOC strengthens after an
interval of weak circulation, it
doesn’t just return to its ‘normal’
extent but it gets stronger than
before – it ‘overshoots’.
These changes can have extreme
effects. During the Bølling-Allerød
(B-A) warm phase, 14,600 years
ago, temperatures rose by 9°C over
the course of just a few decades.
To find evidence that this
increase was indeed linked to an
overshoot, the scientists looked at
a sediment core from the South
Atlantic Ocean, and related
changes in the core to the abrupt
temperature
changes
observed in the
surface ocean and in ice cores
from Greenland. Their results are
published in Nature Geoscience.
The radiocarbon content and
preservation of carbonate shells
in the sediments indicate that
the waters over the sample site
during the B-A period have all the
characteristics of NADW. This
suggests an overshoot did happen,
because it means that NADW was
carried much deeper than normal,
pushing the older southern waters
out of the
way.
These results
are particularly significant
because they show the AMOC
overshooting to well beyond
its present-day state. And when
overshoots occur, the effects on
surface temperature are extreme.
And such extreme changes
aren’t just geological phenomena.
‘Humans were around in northwest Europe when some of these
events happened,’ Barker adds. ‘I’d
love to know what they made of
such massive climate change.’
Birds prefer non-organic wheat
Birds prefer conventionally
grown grain over organic when
given the choice. This doesn’t
mean that organic foods are
bad, say researchers; the birds
probably just find the more
protein-rich conventional seed
more satisfying.
The findings come from
the first of a set of long-term
experiments by Dr Ailsa
McKenzie of Newcastle
University.
‘The difference between
organic and conventionally
grown seeds is not a matter
of taste – it takes time for the
birds to tell one from the other,’
she says.
McKenzie and Newcastle
colleague Dr Mark
Whittingham offered a group
of 12 canaries a choice of
organic and conventionally
6 Planet Earth Autumn 2010
grown wheat seeds, then patiently
counted how many times the birds
pecked at each bowl.
‘Overall the birds preferred
conventional grain over organic,’
says McKenzie. During the
experiment the canaries chose the
non-organic wheat 66 per cent of
the time. As the days passed and
the birds learned the difference
between the two foods, their
preference for conventional wheat
increased.
Over the next two winters
they repeated the experiment
in 47 gardens across Newcastleupon-Tyne and Northumberland,
measuring how much organic and
non-organic grain was eaten daily
from two feeders. As before, the
birds preferred the conventionally
grown seed.
But how do the birds tell the
difference between grain from
organic farms and
wheat grown with
the help of fertilisers
and pesticides?
‘It’s not the
taste, because the
preference takes
time to develop,’
says McKenzie. So it
must be something
innate to the
grain. Wheat from
conventionally fertilised crops
often has more protein. ‘It is likely
that after a while, the birds begin
to sense that conventional wheat
has more protein,’ she says, adding
that maybe they find this proteinrich diet more satisfying.
To test if the birds can learn
to spot high-protein wheat, the
team went back to the lab. They
chose two types of wheat grown in
the same conventional farm, but
treated with different amounts
of fertiliser. The only difference
between these types of nonorganic grain was that the overfertilised crop had more protein.
‘The canaries ate less lowprotein than high-protein
wheat throughout the trial,’
says McKenzie, who reported
the results in the Journal of the
Science of Food and Agriculture.
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Ocean currents
ended last ice age
The last ice age came to a stop soon after carbon dioxide
levels in the atmosphere started to rise about 18,000 years ago.
Now researchers have found the possible location of a carbon
dioxide leak from the Southern Ocean around Antarctica that
helped speed up the process.
‘The Southern Ocean is one of the areas where deep and cold
water surfaces,’ explains lead author Dr Luke Skinner, an earth
scientist from the University of Cambridge. ‘This deep water is
rich in carbon dioxide, which can be released when the water
comes in contact with the atmosphere.’
‘Our results show that during the last ice age, around
20,000 years ago, carbon dioxide dissolved in the deep water
circulating around Antarctica was locked away for two or three
times longer than today,’ says Skinner.
The findings, published in Science, are the first direct
evidence that the time carbon spends in the deep ocean
increased substantially during the last glacial period. This
helped to keep atmospheric carbon dioxide levels low and the
world in a deep freeze.
Skinner and colleagues discovered the link in the shells of
tiny bottom-dwelling micro-organisms called foraminifers.
They compared the carbon-14 in the shells, which was
absorbed from the water where the foraminifers lived, with the
carbon-14 in the atmosphere at the time. The difference let the
team work out how long the CO2 in the deep water had been
locked away from the atmosphere.
‘We found that water sitting deep in the Southern Ocean
was older during the last ice age,’ says Skinner. This confirms
the suspicion that ocean circulation drives at least part of the
changes in atmospheric carbon dioxide between glacial and
interglacial times.
But the mechanisms for this are still uncertain. ‘Our guess at
this point is that changes in sea-ice extent were crucial in letting
the winds stir up the ocean around Antarctica, and effectively
lift water to the sea surface as a result,’ Skinner says.
In brief
Ecologist snaps up photography prizes
Cardiff University’s Adam Seward has won two of the five awards in
this year’s British Ecological Society photographic competition.
Adam was doing fieldwork in Fair Isle when he took the
photographs of a puffin (Fratercula arctica) and wheatears (Oenanthe
oenanthe) to scoop the Ecology in Action and Student categories.
NERC supported his visit to Britain’s most remote inhabited island
as part of his PhD.
No stranger to photographic fame, Adam’s work has been
widely published and he was highly commended in the prestigious
European Wildlife Photographer of the Year competition in 2009.
Bioblitz on into autumn
Building on the success of the summer Bioblitz events, the Bristol
Natural History Consortium (BNHC) is coordinating a further series
of mini events on university campuses around the country, and
NERC scientists will be on hand to help. Details are on the BNHC
website, www.bnhc.org.uk/home/bioblitz, and you can keep up to
date on Twitter @BioBlitzUK and Facebook BioBlitzUK.
Snakes in dramatic decline
Snake populations around the world have declined sharply over
the last 22 years, and Britain’s smooth snake Coronella austriaca
is among the species showing the sharpest drop. Scientists think
a change in habitat quality – like a reduction in the prey available –
rather than habitat loss, could be to blame.
‘It’s too coincidental for snakes from so many countries to be
going through the same steep decline. There has to be a common
cause,’ says Dr Chris Reading from the Centre for Ecology &
Hydrology, who led the research published in Biology Letters.
Open Data
From January 2011 NERC will make the environmental data in its
Data Centres freely available without restrictions on use. This is to
increase the openness and transparency of the research process,
and to encourage the development of new and innovative uses for
these data. To help support this, NERC will require environmental
data collected from the activities it funds to be made openly
available within two years of their collection.
These are just a couple of the changes that NERC will make with
the introduction of its new Data Policy. The policy will be launched
in October and will come into force in January 2011. See the NERC
website, www.nerc.ac.uk, for more information.
Planet Earth Autumn 2010
7
DAILY UPDATED NEWS www.planetearth.nerc.ac.uk
News
Antarctica’s enigmatic
Gamburtsev Subglacial
Mountains unveiled
New images of the Gamburtsev Subglacial Mountains (GSM)
were presented at the International Polar Year conference in Oslo
in June, showing the features of this enigmatic mountain range in
unprecedented detail.
Scientists from the British Antarctic Survey (BAS) were part of
the seven-nation Antarctica’s Gamburtsev Province project (AGAP),
which has completed an airborne survey of 20 per cent of this
previously unexplored area.
The images clearly show the GSM’s high-relief, alpine-style
landscape, and the profiles show that the valleys were carved by rivers
as well as ice.
‘It’s likely that the valleys were initially eroded by rivers, which
points to the fact that the mountains were there long before the ice
began to form, about 35 million years ago,’ says Dr Kathryn Rose of
BAS. ‘As temperatures fell, glaciers formed on the highest peaks and
followed the path of the existing drainage system.’
But the fact that the mountain peaks have not been eroded into
plateaus suggests the ice sheet could have formed relatively quickly.
Amazingly, the radar also showed there’s liquid water under the ice.
Scientists had to endure surface temperatures of around -30°C during
the survey, but the temperature under the ice is as high as -2°C.
‘This is because the ice acts like a blanket,’ says BAS’s Dr Tom
Jordan. It traps geothermal heat and its immense pressure causes
Perspective view of GSM’s peaks and valleys.
water to melt at lower temperatures than it does at the surface, so the
water can exist as liquid at the base of the ice.
Studying this subglacial environment will help scientists understand
how the region’s climate has changed – and how the ice has responded
– over tens of thousands of years.
‘Meltwater from one place is moving through the system and seems
to be freezing back onto the base of a different part of the ice sheet.
This new process hasn’t been taken into account in previous ice-sheet
studies,’ adds Jordan.
Another key finding is that the mountains are not volcanic. The
researchers found signs of ancient tectonic fabric – areas of rock that
have been pushed together or slid past each other.
Today the GSM aren’t close to the edge of a tectonic plate, so these
readings provide important clues to their age: ‘significantly more than
500 million years old’, says Jordan.
Old males rule the roost even as sex-drive fades
Old male chickens can still
rule the roost even when their sex
drive and ability to fertilise eggs
nose-dive with age.
This leads to disastrous results
for hens. Being monopolised by
an impotent rooster means they’ll
lay many more infertile eggs than
if they’d mated with a younger
model.
‘What we’re seeing is an
evolutionary battle between what’s
good for roosters and what’s good
for hens,’ says Dr Rebecca Dean
from Oxford University, co-author
of the study published in Current
Biology.
Dean and her co-authors looked
at a natural population of domestic
chickens (Gallus gallus domesticus)
to study various components of
8 Planet Earth Autumn 2010
reproductive success like sperm
count, sex drive and how well old
roosters’ sperm swim.
‘We wanted to find out how
different components of male
reproductive success affect roosters’
overall fertility as they age. But
also how this impacts on females
within groups,’ explains Dean.
The researchers found that,
compared with their younger
competitors, older roosters had a
lower sex drive, were more likely
to fire blanks and produced fewer
sperm of lower quality.
But they were surprised to find
that if old roosters were faced with
just a few young competitors in
groups with plenty of females, they
were just as likely to rule the roost
as younger males. And in groups
dominated by an old rooster,
females lay lots of infertile eggs.
When there are plenty of young
males around, though, old roosters
were much less likely to become
dominant.
‘To females, dominant roosters
suggest good genes. But the fact
that they can still be dominant
while being infertile is bad news
for hens,’ says Dean. ‘At the
moment, we don’t know if females
can detect whether or not older
roosters are infertile.’
What isn’t clear is whether hens
get any benefit at all from mating
with older males.
‘There are still many questions
we’re keen to answer,’ says Dean.
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Archaeologists find
Britain’s oldest house
The remains of what’s thought
to be the oldest house in Britain
have been found at Star Carr, near
Scarborough, near traces of an
ancient lake.
Archaeologists at the Universities
of York and Manchester say the
3.5m-diameter circular dwelling
dates from at least the early
mesolithic period – 8500BC. It
was last used just after the last ice
age, when glaciers had retreated
from much of Europe but sea levels
hadn’t yet risen enough to cut
Britain off from the Continent.
The house is older than the
previous record-holder, at Howick
in Northumberland, by at least 500
years.
The people who lived there were
hunter-gatherers, pioneers who were
colonising this landscape not long
after the glaciers’ retreat had made
it habitable again.
‘This changes our ideas of the
lives of the first settlers to move
back into Britain after the end of
the last ice age’, says Dr Chantal
Conneller of the University of
Manchester, one of the directors
of the project. ‘We used to think
they moved around a lot and left
little evidence. Now we know they
built large structures and were very
attached to particular places in the
landscape.’
She adds that her whole team of
12 people managed to squeeze into
the space available, so it could have
sheltered a relatively large group.
Excavations also revealed a
wooden platform or trackway that
could have let people cross the
boggy terrain to reach the lake. It’s
made from wood that could be as
much as 11,000 years old.
The archaeologists found 18 post
holes around the edge of the house,
which probably held vertical posts
supporting its roof, and a central
fireplace. This kind of structure,
or larger versions of it, is common
500-1000 years later, but this is the
first known example from the early
mesolithic.
The archaeologists think there
could be more structures nearby.
English Heritage has signed an
agreement with the farmers who
own the land at Star Carr to help
protect the remains. It is now
investigating whether a largerscale dig is needed to recover more
information before it’s lost for ever.
Artist’s impression of mesolithic hunter-gatherers at a temporary camp near Star Carr. From an original
drawing by Alan Sorrell.
Africa’s national parks
not working properly
Numbers of zebras, giraffes,
lions and other large mammals
have plummeted by a staggering
59 per cent across Africa’s
national parks since the 1970s,
according to the first-ever study
of the parks’ effectiveness. The
likeliest explanation is overhunting and changing habitats,
both of which are driven
by fast-expanding human
populations.
Africa’s national parks cover
five million square kilometres
and are meant to play a vital
role in defending some of the
best-known species on the
planet. But, until now, no one
has looked in detail at whether
or not they work.
Ian Craigie, who led the
research during his PhD at
the University of Cambridge,
and colleagues from the
Zoological Society of London
collected data for 583
mammal populations from 78
Protected Areas. They found
the steepest declines in large
mammals in western Africa,
while the only region in which
populations grew was in the
south of the continent. Their
report is published in Biological
Conservation.
‘Southern African parks are
much better funded than parks
across the rest of Africa. They
have more staff and so are better
at defending against poachers
and other threats,’ explains
Craigie. ‘There’s generally a
good correlation between good
management and a lower risk of
threats like hunting.’
Craigie is keen to emphasise
that ‘many creatures like rhino
and wild dog only exist in the
national parks. If it wasn’t for
these parks, the situation might
be far worse.’
‘In most parks, managers
know their jobs. They know
what’s happening, but they don’t
have the resources to deal with
it,’ he adds.
Planet Earth Autumn 2010
9
The impact
of impacts
In remotest Arctic Canada, scientists are
discovering that life can exploit the harshest
of conditions on our planet – not the Arctic
winter, but the aftermath of a massive
meteorite collision. Could traces of life be
found in this sort of area on Mars too?
Adrian Boyce and John Parnell tell us more.
Fragments of rock in the soil zone, Haughton impact
structure, where iron sulphides are weathered to rustycoloured sulphate minerals. Analysing these is valuable as
an analogue for exploration on the highly oxidised martian
surface, where sulphates are widespread.
10 Planet Earth Autumn 2010
D
isaster movies like Deep Impact with
comets colliding catastrophically with
Earth inevitably involve the extinction
of ‘life as we know it’. And just ask
the dinosaurs how big an influence meteorite
impacts have on survival prospects on our
planet! But, that doesn’t mean that all life is
destroyed by impacts. Far from it – our recent
research is providing evidence that some
bacteria may actually thrive in the thermal
spring systems these events leave behind.
These bugs leave behind distinctive chemical
traces, and we may be able to find similar traces
in the impact craters of Mars. Discussions are
under way to develop instruments for future
Mars landers to do just that.
The Haughton impact crater lies in the
wilderness of the Canadian High Arctic on
Devon Island – the largest uninhabited island
on Earth. Nearly 40 million years ago, a
meteorite two kilometres across crashed into
Earth, leaving behind a 23km-wide crater in
the bedrock and causing serious damage over
an area of 50km2. It melted stone and formed
what are known as impact ‘breccias’ – a tell-tale
pattern of smashed rocks.
In fact the movies exaggerate only slightly.
These asteroids do strike with enormous speed
(more than 10km a second). On impact, much
of this energy dissipates into the rocks around
as heat, generating temperatures of thousands
of degrees centigrade. The rocks the meteorite
encountered were mainly ancient carbonates,
around 470 million years old, but they also
contained thick beds of sulphate salts, called
gypsum. These are the remnants of ancient
seas and lakes that dried up, of which there are
many examples through geological time.
The sulphates around the Haughton crater
were broken up and even melted by the impact.
In some areas they were dissolved by the
scalding water circulating around the newly
formed underground fractures and voids – a
natural mechanism called a hydrothermal
system that cools the Earth after such events.
This system lasted for around 10,000 years –
THE IMPACT OF IMPACTS
Researchers carry out sampling in the Haughton impact structure breccias.
this sounds a long time to us, but in geological
time is just the blink of an eye.
The occurrence of sulphate also sparks an
intriguing possibility. Sulphate is at the heart of
one of the oldest and most important biological
metabolic functions on Earth – bacterial
sulphate reduction. Just as we metabolise
oxygen and organic matter to produce carbon
dioxide, so sulphate-reducing bacteria (SRB)
metabolise sulphate and organic matter and
produce hydrogen sulphide, a chemical with a
characteristic rotten-egg smell that makes it a
favourite ingredient in stink bombs.
Of microbes and meteorites
Detlev Van Ravenswaay /Science Photo Library
SRB can live only where there is no oxygen,
so they are generally found in soils, mud on
the seabed, or even deep in the Earth in what
scientists have called the deep biosphere.
Wherever there’s sulphate, organic matter and
no oxygen you’re likely to find SRB activity –
even at extreme temperatures.
Much of the hydrogen sulphide they produce
escapes into the atmosphere, but some of it
combines with iron in the surrounding rocks
and mud to produce iron sulphide minerals.
Most commonly these are pyrite – fool’s gold
– but also another compound called marcasite.
Both minerals are abundant in cracks and
fissures in the Haughton impact breccia,
deposited by the flowing hydrothermal waters.
However, there are other natural processes
that can make iron sulphides with no need for
living things. So, how could we tell that SRB
were responsible if all this happened many
millions of years ago?
We looked at the precise chemical make-up
of 25 samples of iron sulphide from all over
the crater, and found a distinctive chemical
signature, very different from that which can
arise without the presence of life.
Atoms of the same chemical element come
in different varieties, called isotopes. All atoms
of an element have the same number of protons
– that’s why they’re the same element. But the
number of neutrons in the atom varies. Some
kinds of sulphur have more neutrons than
others, and we found that the split between
different sulphur isotopes in the Haughton
crater sulphides could have arisen only through
the activity of microbes.
SRB much prefer the slightly lighter
sulphur-32 isotope to the heavier sulphur-34
variety, so the sulphides they produce contain
lots more sulphur-32 than sulphur-34. This isn’t
the case with sulphides that form naturally. So,
there’s little chance this isotopic signature could
have been produced by a non-biological process
– the difference between the starting sulphates
and the eventual sulphides is just too great.
Furthermore, we have found that when
this ‘bacteriogenic’ sulphide is oxidised back
to sulphate by exposure to the weather at the
surface, there is very little change from the
original sulphide isotopic value. This means that
even these sulphate minerals retain the tell-tale
sulphur isotopic signature after weathering.
Among those planetary bodies nearby which
are thought most likely to harbour life are Mars
and Europa, one of Jupiter’s moons. It also
seems that their surfaces are rich in sulphates,
left behind from the gases given off by
ancient volcanoes. This abundance has fuelled
speculation that simple life on Mars could set
energy from the transformation of sulphur
compounds – sulphur metabolisms are thus a
credible component of life on Mars.
Areas of Mars that are thought to be rich
in sulphate have already been identified as
priority targets in the search for life. Our
new observations of widespread sulphide
precipitation, mediated by bacteria, in impact
breccias in a sulphate-rich terrain, indicate
that martian sulphur minerals in impact crater
settings should be strong candidates for sulphur
isotopic analysis, and that the next missions
to return to Mars should aim to gather such
samples.
A programme has also started to develop a
mass spectrometer system to do the analysis via
laser-based instruments on a lander. It may be
that the answer to the question of whether there
is life out there could be just a laser zap away.
More information
Dr Adrian Boyce is manager of the NERC Isotope
Community Support Facility at the Scottish
Universities Environmental Research Centre.
Professor John Parnell is Chair in Geology and
Petroleum Geology at the University of Aberdeen.
Email: [email protected].
FURTHER reading
Parnell, J, Boyce, A et al (2010). Sulfur isotope
signatures for rapid colonization of an impact crater
by thermophilic microbes. Geology, 38, 271-74.
Planet Earth Autumn 2010
11
Current
thinking
Fine-tuning ocean observations
When we think about the oceans and their
role in Earth’s climate, we tend to think of big
features like the Gulf Stream and the impact of
Arctic melt water. But oceanographers know
that the devil is in the detail. Roz Pidcock tells
us how her research expedition to Iceland took
ocean observation to new depths.
G
reen plants are the basis of the food
chain in the ocean, just as they are
on land. Microscopic floating algae,
called phytoplankton, photosynthesise
and remove carbon dioxide (CO2) from the
atmosphere, just like the plants in your garden.
This makes them important for regulating
climate because as the phytoplankton die and
sink down to the bottom, they transfer carbon
from the surface ocean to the deep sea, where
it can be stored away for many thousands of
years. But what controls this photosynthesis?
One important factor is how much of the main
nutrient for phytoplankton growth – nitrate
(NO3) – is available in the water.
Phytoplankton live in about the top 50
metres of the water column – typically the
depth to which sunlight penetrates. When they
grow in very large numbers, such as in spring
when there’s plenty of light and food around,
they can quickly use up all the readily available
nitrate. That’s where my fieldwork comes in.
I am studying ocean features called eddies
and filaments. Eddies are circular, rotating
currents up to 100 kilometres (around 60 miles)
wide, which are found throughout the world’s
oceans. They usually form where two bodies of
water with different densities meet, for example,
in the north-west Pacific where the cold
Oyashio current coming down from the Arctic
meets the warmer Kuroshio current flowing in
from the south.
12 Planet Earth Autumn 2010
Giant stirring spoons
Eddies act like giant spoons, stirring up the
water to depths of hundreds of metres. As
eddies turn, ribbon-like filaments form at their
edges, just like you see when you stir milk into
a cup of tea. These filaments can be stretched
many tens of kilometres in length, but may be
just 1000 metres across. The longer they stretch,
the narrower they become.
Eddies and filaments can be very efficient at
supplying nitrate to phytoplankton, because
their horizontal circulation is accompanied
by vertical motion that brings deep water
up to the surface. Because it has been below
the sun-lit layer and beyond the reach of the
phytoplankton, this water is high in nitrate.
Computer models and observations have
shown that eddies can contribute a significant
amount of the total nutrients needed each year
in some parts of the ocean. And over the last
decade, as models have become more refined,
they have begun to show that the filaments may
be at least as important as the eddies.
Clever computer models are all very well,
but actual observations of nutrient supply
within filaments are in short supply. This is
partly because of the limited sensitivity of the
equipment available to measure nitrate, and
also because until recently, most in-situ studies
have focused just on the eddies. So, in summer
2007, we set off towards Iceland aboard RRS
Discovery, to try to redress the balance.
Eddies and filaments in the Iceland
Basin
We took two crucial pieces of kit with us, one
of which – an ultra-violet (UV) nitrate sensor
– had been specially developed at the National
Oceanography Centre in Southampton. Nitrate
absorbs UV light at certain wavelengths, so by
shining it through the water and measuring
how much comes out the other side, we can
calculate how much nitrate is present. But
until now nitrate sensors have only really been
effective where concentrations are high and
where changes in concentration are sharply
contrasted (for example, as you move away
from high-nutrient coastal water into the open ocean).
But filaments involve much smaller changes
in concentration and appear and disappear
relatively quickly over short distances. Small
concentration differences are still important
as they may contribute to significant vertical
transport of nitrate when combined with fast
upward movement of water. So we developed
the SUV-6, a nitrate sensor that uses a series of
prisms rather than fibre optics, making it about
ten times more sensitive than its predecessors.
The SUV-6 was deployed within our other
piece of equipment – SeaSoar. This small,
computer-controlled vehicle was towed behind
Discovery carrying a number of different
sensors. It travelled repeatedly in V-shaped
profiles, from the surface to a specified depth
current thinking
Norman Kuring/MODIS//NASA
SeaSoar on deck.
When two currents (in this case the Oyashio and Kuroshio
currents) collide, they create eddies. Phytoplankton become
concentrated along the boundaries of these eddies, tracing out
the motions of the water.
and back up again, measuring temperature,
salinity, chlorophyll fluorescence, oxygen
and light intensity, every second. SeaSoar has
been used many times to survey the physical
characteristics of eddies, but this was the first
time it had carried a nitrate sensor that could
also take accurate measurements every second,
at the same time as the physical measurements.
We were very excited about what it might
reveal.
could tell how the water was moving, how fast,
and how much vertical water movement was
taking place.
But the really good bit came when we looked
at the simultaneous nitrate measurements
from the SUV-6. These enabled us to calculate
the amount of nitrate being transported at
every point in our 3-D grid. For the first time,
instead of just using a few individual profiles to
infer nitrate transport over the whole eddy, we
were able to work with
a continuous dataset,
meaning our calculations
were far more accurate
than has been possible in
the past.
These unique
results mean we can
investigate how the
nitrate moves around
relative to different parts of the eddy – its spatial
variability. And, because we carried out four
similar surveys over the course of four weeks,
we can also study the temporal variability –
how the spatial patterns change with time.
We can also calculate the overall nitrate
transport at a particular depth for the whole
eddy feature, to see if there is an overall upward
or downward flux, or movement, of nitrate, and
how big it is. This is important to understand
how the eddy feature as a whole contributes to
phytoplankton growth in the upper sunlit layer
Eddies can contribute a
significant amount of the total
nutrients needed each year in
some parts of the ocean.
Despite giving up a large part of our survey
time to avoid a lively tropical storm, we
identified our target: a pair of eddies, each
about 50 kilometres in diameter. We could
see on satellite images that there were several
filaments associated with this eddy pair. We
towed SeaSoar along nine parallel tracks, each
around 100 kilometres long, which crossed the
eddies from east to west. Four days later, at the
end of the survey, we had a very detailed 3-D
picture of the temperature and salinity of the
eddies, and after some complex calculations we
of the ocean. Finally, and most excitingly for
us, we can make an accurate assessment of the
vertical movement of nitrate associated with
any point inside a filament, to test the models’
suggestion that transport within filaments is
just as important as within the main eddy.
So what next?
We are still analysing the results from our trip
to the Iceland Basin. But we already know for
sure that integrating SUV-6 into SeaSoar has
created a powerful tool for studying the role of
eddies and filaments in supplying nutrients to
ocean plants.
More surveys like ours will dramatically
increase our understanding of oceanic processes.
Direct observations of eddies and filaments will
help make ocean models increasingly realistic
and improve our understanding of the role of
oceans in climate-change predictions.
FUrther information
Roz Pidcock is a PhD student at the National
Oceanography Centre in Southampton.
Email: [email protected]
www.noc.ac.uk
FURTHER READING
Pidcock, R et al, A novel integration of an ultra-violet
nitrate sensor on-board a towed vehicle for mapping
open ocean submesoscale nitrate variability. Journal
of Atmospheric and Oceanic Technology, August
2010
Planet Earth Autumn 2010
13
AGAVE
Biofuel of the future?
Traditionally grown for tequila and fibre, agave
could also become an important source of
energy in the dry regions where it thrives.
Andrew Leitch, Theodosios Korakianitis and
Manuel Robert describe their team’s efforts to
investigate this plant group’s energy potential.
14 Planet Earth Autumn 2010
T
he trend towards replacing fuels derived from oil with cleaner
renewable ones generated from living organisms is a very attractive
proposition, but it’s full of potential problems that need to be
addressed in detail.
Recent events in the Gulf of Mexico make biofuels even more relevant, in
the light of the environmental problems associated with the oil industry.
But we need to make the new methods as efficient and environmentally
friendly as possible, and to find the right strategy for different regions of
the world so that new fuels are economically competitive.
Producing new fuels locally would reduce the very high costs
of transporting them from one place to another and the risks of
contaminating the environment. Also, crops used to produce biofuels
must not affect the production of food or alter its markets. This has
already happened to Zea mays (maize) production in the Americas, where
demand for maize as a biofuel, food and fodder crop led to higher prices.
All this means we will need more than one strategy to satisfy an energyhungry world while taking account of the threat of climate change,
the market laws of price competition and the specific needs of different
countries. Agaves could play an important role.
For many years, these plants have been a source of products including
sugars for producing alcoholic drinks like tequila, and hard fibres such
as henequen and sisal for making products including ropes, twine and
bags. But these same raw materials could become an important source of
biofuels, whether bioethanol or biodiesel.
Agaves are perennial plants that produce large leaves in a rosette form.
Their size and lifespan vary enormously between species, from 20 to
200cm in height and between 8 and 30 years old. Cultivated agaves
agave – biofuel of the future?
Russell Gordon/DAS FOTOARCHIV./Still Pictures
benefit from adequate water from rain, but most
are well adapted to arid conditions, and tolerate
high temperatures and water shortages. This
means they can be grown on land that would
not be suitable for other purposes, and where
soils are easily degraded by disturbance.
It is not clear whether these plants can
become an economically competitive alternative
source of biofuels, but their biomass and growth
characteristics make it worth looking into the
possibility, particularly given the dry conditions
that climate change may create in many parts of
the world.
How to exploit the plant depends on the
type of agave and the final product aimed for.
Alcohol is made by fermenting the sugars stored
in the plant’s ‘bole’, or stem, after many years
of growth, while biodiesel could be produced
using fast pyrolysis, burning the biomass
harvested regularly from fibrous agave leaves.
The most efficient alcohol-producing agave is
Agave tequilana Weber, best known as the blue
agave from which tequila is made. The industry
generates an average of 120 tons of boles per
hectare every six years, from which 20,000 litres
of tequila (46 per cent alcohol) are produced.
One of the most important questions is how
to transport the raw material to the processing
plants. This calls for small facilities near the
industry’s centres of operation. This is nothing
new; in Germany, hundreds of small plants
that make methane from agricultural waste
are being strategically placed near farms, and
the production facilities of companies that use
fast pyrolysis to generate crude biodiesel are all
found near where the crops are grown.
Agaves produce considerable biomass,
though not nearly as much as annual crops. A
key advantage would be that no new planting
is needed, and it takes relatively little work to
maintain existing or new plantations.
It is also possible to use waste leaves left by
the tequila industry, or the stems and short fibre
Harvesting agave leaves on a sisal
plantation in Tanzania.
discarded during henequen or sisal production.
This might not generate very much biodiesel,
but it would not require any extra expenditure
on establishing and running new plantations, or
on fuel to move products long distances.
Another alternative for biofuel production
has already been implemented in Tanzania – a
plant that makes biogas from the controlled
fermentation of the liquid waste generated
when leaves are decorticated – their outer layers
removed and their fibres extracted. The gas,
methane, is burnt on site to generate electricity.
This in turn powers the decorticating plant and
the small town nearby. Any that is left over is
sold to the national network.
The best fuel will be suitable for combustion
engines. We now need to examine different
species and varieties of agave to determine how
best to produce biofuels for this use. We will
soon be seeking funding to let us select fuel
production processes, engine materials and
fuel mixtures suitable for combustion engines,
taking into consideration engine performance
and the emissions of agave-derived biofuels.
Improving the crop
Ron Giling/Lineair/Still Pictures
The main problem when considering agaves for
industrial purposes is that they have not been
studied in detail. There are many taxonomical
studies, classifying different agave species
according to where they fit into the wider
group, but only a small number of papers have
been published on functional aspects of their
biology such as genetics, biochemistry and
physiology.
We have made a start on this study
by analysing the genome organisation of
commercially grown agave species and
generating physical and genetic maps.
These maps can be used to find agave lines
most suitable for using targeted breeding to
create new varieties with particular desired
characteristics, using strategies already well
developed in breeding new
varieties of other crops.
However, most agaves
spread vegetatively through
rhizomes – underground
root-stalks. This is an
advantage when producing
planting material, as this
can be done simply by
taking cuttings. But it
presents us with a challenge
for genetic improvement,
as it’s hard to combine
the genes of two different
plants by breeding them.
So far, the only successful
programme to genetically improve agaves was
carried out in Tanzania during the first half
of the twentieth century. Then, it took George
Lock around 30 years to produce a family of
hybrids that produce long fibre. We hope to
make progress more quickly than that.
New, more efficient and faster-growing
varieties will be needed, and we plan to use
new molecular techniques, such as the use of
genetic markers to help selectively breed plants
with desired characteristics, together with
new methods to grow plant tissues efficiently.
These advances will shorten the time needed
to generate new plant materials. A programme
for the genetic improvement of Agave tequilana
using these techniques is already under way in
Mexico. However, much more work is needed.
The best way to use agaves will depend on the
special circumstances of the place where they
will be grown, and a combination of options
may be called for. However, since agaves have
not been genetically improved in a consistent
way, the most important initiative to consider
is a large-scale, long-term programme for the
selection and generation of new agave types that
will be more suitable for biofuel production.
Even using the best modern genetic
techniques, this process of selective breeding
will be long and difficult. But in the end it
could provide us with new and useful sources
of renewable, carbon-neutral energy that can
thrive in hot, dry conditions. It could be grown
across large tracks of land that currently have
little agriculture, or only subsistence farming,
and often limited conservation value. This
means the industry doesn’t just offer cleaner
energy; it could also bring wealth to people who
suffer from extreme poverty.
More information
Andrew Leitch is Professor of Plant Genetics and
Theodosios Korakianitis is Professor and Chair
of Engineering, both at Queen Mary University
of London. Dr Manuel Robert is a member of
the biotechnology department of the Centro de
Investigación Científica de Yucatán in Mexico. Email:
[email protected], [email protected] or
[email protected].
FURTHER READING
Korakianitis, T, Namasivayam, A, and Crookes, RJ,
(2010). Natural-gas fueled spark-ignition (SI) and
compression-ignition (CI) engine performance and
emissions. Progress in Energy and Combustion
Science, doi:10.1016/j.pecs.2010.04.002.
Robert, ML, Lim, KY, Hanson, L, Sanchez-Teyer,
F, Bennett, MD, Leitch, AR and Leitch, IJ (2008).
Wild and agronomically important Agave species
(Asparagaceae) show proportional increases in
chromosome number, genome size, and genetic
markers with increasing ploidy. Botanical Journal of
the Linnean Society, 158, 215-22.
Planet Earth Autumn 2010
15
The Earth’s magnetic field. The magnetic
poles are shown as red lines. Magnetic field
lines (orange) can be seen emerging from
the south magnetic pole and converging
at the north magnetic pole, which is offset
from the geographic north pole (blue lines)
by eleven degrees.
Mark Garlick/Science Photo Libarary
To go north, you just follow your compass towards magnetic
north, right? Not quite. Geophysicists have to work hard so
we can continue to navigate with map and compass. Susan
Macmillan and Tom Shanahan describe how the UK magnetic
repeat station network helps.
Where is North?
T
o find your way using a magnetic
compass with a map, you need to know
the difference between magnetic north
and map north. This difference is called
‘grid magnetic angle’, and in the UK it is
derived from a model of the Earth’s magnetic
field, which is updated every year. The variation
in grid magnetic angle reflects changes in the
Earth’s magnetic field arising from sources
in the Earth’s fluid outer core. We don’t yet
understand these changes well enough to make
good forecasts, so we need to monitor them
continuously.
Some of the data we need has been provided
by an important, UK-wide network of magnetic
survey stations that has been operating since the
early 20th century.
At these ‘repeat stations’, very
accurate measurements are
made of the magnetic
field strength and
direction over a
whole day,
every few years, at exactly the same place. The
readings are influenced by different sources
of magnetism (see explanations to the right)
and all these need to be carefully considered
when making and processing magnetic field
observations.
For example, in the UK the horizontal
direction of the main field is currently changing
by about 0.2° each year. But we can also see this
much variation between sites just a few metres
apart because of variations in the crustal fields.
Taking repeated measurements at exactly the
same spot lets us measure the core magnetic
field signal without the risk of distortions from
changes in the crustal field.
Likewise, variations in the magnetosphere
surrounding the Earth cause the overall
magnetic field to fluctuate by about 0.2° each
day in the UK, and by considerably more
during a magnetic storm. During a storm in
October 2003 the magnetic field direction was
observed in the UK to change by over 5° in
six minutes. Fortunately these variations are
short-lived compared to those from the core.
We measure them at the three UK magnetic
observatories, and can then subtract them from
the repeat station data.
Having processed and modelled the data,
16 Planet Earth Autumn 2010
Pasieka/Science Photo Libary
where is north?
Magnetic field sources
n
The Earth’s magnetic field mostly arises
from the motions of fluid in the Earth’s
outer core region, and changes slowly
with time.
n
Weaker fields from magnetic material
in local rocks (the ‘crustal field’) vary
significantly over the surface of the Earth
– often aiding geological interpretation –
but not so much with time.
n
The Earth’s magnetosphere – where the
planet’s magnetic field interacts with
charged particles from space – causes
variations in the observed magnetic field.
These are affected by the Sun’s activity,
and are relatively rapid compared to those
from the core.
we can update the magnetic charts. We can
see that the correction we need to apply to a
compass bearing to convert it to a map bearing
– and vice versa – varies both in space and in
time. The models are then used to supply the
Ordnance Survey with the magnetic north data
they need for their maps.
East is least, west is best
The earliest observations of the geomagnetic
field in the UK were made in and around
London in the late 16th century. At that
time magnetic north was east of map north.
However it was not until the early 20th century
that we had a genuine repeat station network
covering the whole of the UK with sites that
could be revisited at regular intervals.
Several magnetic surveys were made before
this, though. Perhaps the most noteworthy were
the efforts of Major Edward Sabine between
1834 and 1838. At that time, magnetic north
was more than 20° west of map north. Later he
was to declare that this survey ‘deserves to be
remembered as having been the first complete
work of its kind planned and executed in any
country as a national work, coextensive with the
limits of the state or country, and embracing the
three magnetic elements’.
Sabine also pointed out that such surveys
are able ‘by their repetition at stated intervals
to supply the best kind of data for the gradual
elucidation of the laws and source of the
secular change in the distribution of the
Earth’s magnetism’. These early magnetic
surveys were major undertakings, given the
delicate but sizeable instruments available
at that time and the challenges of travelling
across the country.
Nowadays the instruments used are a
‘fluxgate-theodolite’, allowing us to measure
the direction of the magnetic field, and
a ‘proton precession magnetometer’, for
measuring its strength. We determine the
direction of true north using a north-seeking
gyroscope. Each site is marked by a buried
slab of concrete, and detailed site plans allow
us to set up our equipment in exactly the same
place each time.
The data we get from these stations can also
help us understand the crustal magnetic field.
By measuring the magnetic field at the same
locations very accurately over long periods
of time, we should be able to distinguish
between the different types of crustal
magnetisation. This can be either ‘remanent
magnetisation’, which is ‘embedded’ in rocks
when they form, or ‘induced magnetisation’,
which rocks take on when exposed to the
Earth’s ambient magnetic field.
As the core field changes with time, there
should also be small changes in the crustal
magnetic field if there is induced magnetisation
present – although detecting these very small
signals in measurements that contain signals
from a variety of sources is quite a challenge.
But for the foreseeable future, the main and
most crucial application of the data is likely to
be navigation. You’ll be making use of magnetic
field data next time you use a map and compass
to find the next destination. However it’s also
used whenever something needs to be set up
to point in a precise direction with the help
of a compass. This includes everything from
aligning sundials and satellite dishes, to making
sure mosques face towards Mecca.
More information
Dr Susan Macmillan and Tom Shanahan are
members of the BGS geomagnetism team.
Email: [email protected] or [email protected].
FURTHER READING
Jackson A, Studies of crustal magnetic anomalies of
the British Isles. Astronomy & Geophysics, 2007.
Planet Earth Autumn 2010
17
Reading
nature’s barcode
The sediment left behind by rivers forms a unique record of the
climate, written in sand and gravel. But we’re only starting to
understand how to examine it in detail. Arjan Reesink reports
on words of river history that have never been read before.
Exposed dunes on a bar in the Paraná River, Argentina.
Histories of climatic
change are found
in river deposits
just as the effects of
ice ages are found
in deep ice cores.
They’re just a bit
smaller.
18 Planet Earth Autumn 2010
A
s rivers gradually shift across the
landscape over decades and centuries,
they leave behind deposits of sand
and gravel with a remarkable diversity
of internal layering. The texture of these river
deposits is dominated by inclined layers of
sediment, sorted according to size by the action
of the water.
Don’t be tempted to believe this is all just
plain sand. Repeated sorting and re-sorting
of the sand ultimately builds a vast record of
river history, cryptically written in a natural
barcode that has been the same since the dawn
of time. Can we decipher the response of rivers
to climate change from this barcode?
Mostly hidden from sight by the water,
ripples, dunes and sandbars slowly migrate
downstream over riverbeds. The downstream
slopes of these features on the river bed get
steeper and steeper until they collapse under
their own weight. Miniature avalanches of sand
generate thin, inclined layers as each feature
advances along the river bed.
Until recently, noone was crazy enough
to count these avalanches as well as the little
ripples that migrate over the edge of larger
dunes. But the exercise pays off; little ripples
generate their own unique pattern as they
tumble over the edge of the larger dune slope.
And it isn’t just ripples tumbling over the edge
of dunes. Many different types, sizes and shapes
of bedforms – features of the riverbed landscape
– are found superimposed on one another. Each
combination of bedforms can be produced
only by a limited set of flow conditions, and
each such combination has its own signature.
Changes in river flow are recorded as changes in
the layering of the sediment.
reading nature’s barcode
Different types of strata in a single trench through a sandbar on the South Saskatchewan River, Canada.
The climate controls each river’s temperament
and behaviour, and this is one of the reasons
why we need to understand climate change.
Rivers in flood are serious natural hazards,
and the number and size of floods change with
the climate. Sure, we can use temperature and
precipitation data and make models of how
river discharge and behaviour will change. But
why don’t we look more carefully at the river
records themselves?
If climate controls a river’s behaviour, and
this in turn controls the river’s sedimentary
record, then river records are proxies of the
ancient climate. Histories of climatic change are
found in river deposits just as the effects of ice
ages are found in deep ice cores. They’re just a
bit smaller.
Many paleoclimatologists, spoiled with
deep-sea, lake and ice cores, would argue the
archive preserved in rivers is incomplete and
fragmented. Honestly, do I dare compare river
deposits to ice cores? Of course no records of
temperatures over thousands of years will be
identified from river deposits. The information
in river beds is more subtle than that. If ice
cores are like a chronological story, river
deposits are more like jumbled-up words and
torn-out pages. If it really was easy, it would
have been done already.
The careful experimentation needed to start
translating the barcode means long hours spent
in a gloomy basement with air compressors,
air-pumps and propeller-pumps singing in
deafening harmony. Circulating water and sand
in an experimental setting allows us to observe
and measure river processes without having to
wait for the right flow conditions.
Testing the validity of these experimental
results requires going outside and shovelling
truckloads of sediment from natural rivers.
The sedimentary structures can be seen in
rock cliffs but are easier to place in the context
of the landscape when they are exposed by
trenches dug in river bars. The coarser sand
crumbles faster as the trench face dries and this
makes the structures visible. The fieldwork thus
ranges from making sketches in a local quarry
in a sunny breeze to drop-offs on a sandbar
hours from civilization in the middle of the
Cumberland Marshes: a blank spot on the
Canadian map. Good data often come from the
strangest places.
Decoding the river bed
What new knowledge has this given us? By
carefully controlling the flow of water in an
experimental setting, we have developed a
dictionary to let us translate these natural
barcodes. For example, we now know that
ripples on dunes form layers with reasonably
constant cross-sections that are separated by
thin, fine-grained layers. Ripples exist on dunes
only in very gentle flows, when turbulence only
occasionally affects the sediment.
In real life this means that ripples exist on
dunes in a very narrow range of flow conditions
and when dunes are being replaced by ripples
after the peak of a flood has passed. Ripple-ondune layering tells us about how the river has
flowed. A set of a single dune with evidence of
superimposed ripples represents a short segment
of time; it is like a single word describing a
historical event.
On a larger scale, we can look at the inclined
layers along the length of sandbars to describe
their history of movement. Dunes form on bars,
and bars move fast, when there is a lot of water
flowing in the river. Ripples form on bars, and
Different types of strata exposed by scraping the surface of a
bar on the Paraná River, Argentina.
bars move more slowly, in medium flows. And
during low flows bars emerge and water flows
around them, reshaping their edges. Repeated
floods eventually create recurring cycles of
structures. So sets formed by sandbars are like
pages of text describing historical events.
We have only just begun to realise that
we can get detailed information from river
deposits. It is almost as if we have never read the
contents of the chapters, only the summaries.
We inferred the contents from these summaries,
but were we right?
River deposits are built through cycles
of repeated sorting of sediment, driven by
dynamic interactions between the flow of water
and the river bed, and ultimately subject to
the river’s temperament. They are the product
of changes in their environment and as such
make up a vast record of information about the
ancient climate. It is cryptically written in a
natural barcode, but it is there for anyone who
wants to translate it. Besides now being able to
read nature’s barcode, the most illuminating
aspect of this study is perhaps the realisation
that science can still be pushed forward simply
using a shovel.
More information
Dr Arjan Reesink is currently a post-doctoral
researcher on NERC’s Rio Paraná project at the
Universities of Brighton and Birmingham.
Email: [email protected]
The Rio Paraná project focuses on the dynamics of
one of the world’s largest rivers; see also
www.brighton.ac.uk/parana
Planet Earth Autumn 2010
19
The carbon age
In a radiocarbon laboratory in
Scotland, researchers came
up with a new portable kit to
sample carbon dioxide using a
clay sieve. Mark Garnett tells
us how they’ve taken this
technique to some remote
places, and how it’s shedding
new light on CO2.
The new portable equipment.
20 Planet Earth Autumn 2010
W
hen I tell people I do research
in a radiocarbon laboratory, a
common response is, ‘Oh right,
like radiocarbon dating the Turin
shroud?’ Radiocarbon dating is a valuable
technique for dating objects of historical
and archaeological importance, but it’s also
a powerful tool in the quest to understand
our environment. In particular, because it
deals with an isotope of the element carbon,
radiocarbon analysis can tell us about processes
that are fundamental both to life on Earth and
to our climate.
Radiocarbon analysis was pioneered over
60 years ago, and the technique continues
to be improved. At the NERC Radiocarbon
Facility (Environment) in East Kilbride we have
come up with new techniques for collecting
CO2 for radiocarbon analysis. This is the
story of these new sampling systems, some of
their applications and the insights they have
provided.
CO2 is important to many processes that
occur on Earth, a component of our planet’s
atmosphere and, in terms of climate change,
one of the most important greenhouse gases.
Plants use CO2 from the atmosphere for
growth, through photosynthesis. Most of the
CO2 they absorb will at some stage return to
the atmosphere, but crucially, the time it spends
locked away can vary from less than a day to
millions of years. For example, carbon fixed by
a plant during photosynthesis will cycle through
it very rapidly and may be returned to the
atmosphere as the plant ‘breathes’. Alternatively,
carbon that sits in a plant’s tissues is likely to
end up in the soil when the plant dies, and
depending on the rate of decomposition it
can stay there for decades or even millennia.
In extreme cases, some carbon fixed by plants
millions of years ago is only now being released,
as we burn fossil fuels.
The rate that carbon cycles through
these various routes before returning to the
atmosphere as CO2 has a critical influence on
its concentration in the atmosphere. This is
because the amount of carbon in the Earth’s
atmosphere (mostly as CO2) is small compared
to that in the oceans and on land.
This is where radiocarbon dating comes
in. It tells us how long carbon has remained
in a particular pool (soil, for example) and,
therefore, the rate that it cycles through that
pool. Measuring the radiocarbon in the CO2
leaving the carbon pool can show us directly the
average age of the gas entering the atmosphere.
All this is possible because carbon naturally
occurs in three slightly different forms
(isotopes). Two are ‘stable’, while the third
– radiocarbon – is ‘unstable’, because it’s
David Barrett/Alamy
the carbon age
Collecting soil respired carbon dioxide from Arctic tundra for radiocarbon analysis.
Sampling chambers had
to be tied down to cope
with the high winds and
exposed conditions.
radioactive and decays as it emits radiation. So
its concentration declines over time relative to its
stable counterparts, and measuring the relative
proportions of the carbon isotopes in a material
forms the basis of carbon dating.
In addition, nuclear weapon tests in the mid20th century produced a rapid but temporary
global increase – a ‘spike’ – of radiocarbon in the
atmosphere which can be tracked throughout
the carbon cycle. This spike lets us date very
recent materials, which can’t be done using
conventional carbon dating.
Our challenge was to develop a sampling
system that researchers could use in remote
field sites. Although a few milligrams of carbon
are enough for analysis, in most cases the
concentration of CO2 in the actual samples is
extremely small – typically a suitable sample
would require 5-10 litres of air. Transporting
such volumes in gas sample bags or glass flasks
would be impractical. Alternative methods
such as cryogenic purification – where CO2 is
separated from other gases in air by cooling in
liquid nitrogen at -196°C – are also impractical,
not to mention potentially hazardous in the field.
Sieving the carbon
Thanks to earlier work by researchers at the
East Kilbride lab, we knew the key was a zeolite
molecular sieve. Zeolite is a rather unimpressive
looking clay material which has remarkable
properties. Firstly, it contains a uniform network
of tiny pores which allow small molecules
(including CO2) to pass through but exclude
larger molecules. Secondly, at room or field
temperatures this molecular sieve attracts
certain molecules to its surface – a process
called adsorption – and the type we use strongly
adsorbs CO2. This means that, when we pump
air through the molecular sieve, all the CO2 is
trapped within its pores. Crucially for a system
that has to be used in the field, it has a high
surface area so only a small amount of molecular
sieve is needed to collect a suitable sample. When
heated to several hundred degrees celsius back in
the lab, the sieve releases the stored gas. These
characteristics make it ideal for our purposes.
Our system also uses an infra-red gas
analyser, which measures CO2 concentration in
the air being sampled so we can estimate when
a big enough sample has been collected. It needs
no external power supply and can be easily
transported and operated by one person.
Developing the system has had huge
benefits. For example, in the NERC-funded
International Polar Year ABACUS project it was
used to work out the age of CO2 produced from
decomposing soil in birch forest and tundra
heath (where cold temperatures prevent tree
growth). To collect the samples required daily
hikes over many miles of tundra, and sampling
chambers had to be tied down to cope with the
high winds and exposed conditions (fortunately
they escaped the attention of the numerous
passing reindeer). Results showed that, although
these soils contain carbon that is hundreds of
years old, most of the CO2 emitted from the
soil surface had been fixed from the atmosphere
within the last decade or so. There was also
evidence for much faster carbon cycling in the
forest compared with the tundra heath. This
will have implications for the overall rate of
carbon emissions if forest replaces heath in
these regions, which may be occurring due to
global warming.
The system has also helped investigate
CO2 emissions from UK peatlands, which
contain vast stores of carbon. One surprise
was that deep-rooted plants act as conduits for
greenhouse gases dissolved deep in the peat.
We know that plants like sedges help transport
methane to the peat surface, but it was news
to scientists that they provide a similar service
for CO2 that’s hundreds of years old. And by
connecting the sampling system to a floating
chamber, we managed to collect and date CO2
coming from the surface of peatland streams.
Surprisingly, radiocarbon results show that this
CO2 can be ancient; derived either directly from
deep bedrock weathering or, potentially, from
CO2 taken in by plants more than a thousand
years ago.
As if this isn’t enough, a whole new range
of possible applications have emerged since
we developed the technique so it could also be
used as a ‘passive sampler’. This means that we
simply rely on the CO2 molecules’ own kinetic
energy to get them to the molecular sieve – no
pump required. So the sieve only needs to be
exposed to the atmosphere being sampled to
get sufficient CO2 before it’s returned to the
lab for analysis. This is particularly helpful in
remote and inaccessible locations – for example,
in Arctic Sweden we managed to collect CO2
from underneath the snow during winter for the
first time – completing a whole year’s sampling
without a break. The soil carbon emitted during
the winter (a significant proportion of the annual
total) proved to be of a similar age to emissions
during the growing season.
This isn’t the end of the story though. There
are even more possibilities for applying both
sampling systems, and the study of fossil-fuel
emissions could be a particularly fruitful one.
Because of its extreme age there is no radiocarbon
in fossil fuel, so if we can’t detect any radiocarbon
our samples must be very old (at least 50,000
years old). Our sampling methods could be
used to quantify how much of the CO2 in the
atmosphere comes from fossil fuel, helping us
understand the impact of fossil-fuel burning on
global warming. It could also be used to test for
CO2 leakage from carbon capture and storage
facilities, helping maximise the contribution they
make to reducing our carbon emissions.
Further information
Dr Mark Garnett is deputy head of the NERC
Radiocarbon Facility (Environment), hosted by the
Scottish Universities Environmental Research Centre,
East Kilbride, email: [email protected]
Development of the sampling system was supported
by the NERC Radiocarbon Facility and a NERC CEH
studentship (Susie Hardie) based at the Scottish
Universities Environmental Research Centre, East
Kilbride, and CEH Lancaster.
Planet Earth Autumn 2010
21
buoys
Jobs for the
Two bright yellow, 7m-tall
buoys, bristling with
sensitive instruments, are
providing scientists with
an unprecedented amount
of detail about the English
Channel. Dr Tim Smyth,
manager of the data buoy
project at Plymouth Marine
Laboratory (PML), tells
Kelvin Boot about his
favourite new toys.
S
cientists have been sampling the English
Channel for more than a century,
investigating its biology and chemistry
and monitoring its tides and currents.
The Channel is a complex environment, yet
in many ways is representative of coastal seas
around the UK. The western Channel, off
Plymouth, is especially interesting as it is here
that oceanic and coastal waters meet – an ideal
area to monitor long-term changes brought
about by rising sea temperatures, for example,
or shorter term as the seasons come and go.
Such information helps us understand the
health of the sea, how it behaves and what
affects it. But getting the information has never
been straightforward.
Until recently, the only way we could
collect data was to visit the sampling sites on
our research vessel to take a range of physical
measurements, such as temperature, salinity
and optics or to obtain biological samples
directly from the water for analysis back at the
laboratory. At best we managed this on a weekly
basis, but it’s a highly weather-dependent
activity so there were no guarantees. And while
such long-term data has proved invaluable in
helping us understand longer-term trends and
22 Planet Earth Autumn 2010
jobs for the buoys
therefore large-scale changes in the Channel,
it left a serious gap in our understanding of
what is happening on a daily or even hourly
timeframe.
The deployment in 2009 of our two shiny
new buoys, at the imaginatively named
sampling sites L4 and E1, marked a significant
advance in both the quality of the information
and the ease with which we could get it. The
buoys are autonomous – they send us their data
automatically almost as soon as it’s recorded,
enabling us to fill in the gaps between the
weekly boat-collected samples.
The buoys are part of the Western Channel
Observatory, which combines routine in-situ
sampling with modelling and remote sensing.
Between them they cover a range of conditions.
At around 7 nautical miles off Plymouth, L4
is close enough to shore to tell us about inputs
from the local estuaries. E1 is sampling in very
different conditions, 25 nautical miles offshore
on the open continental shelf, where there
is more of an oceanic character, so the two
datasets provide a comparison of the impact
and timings of any changes taking place.
So apart from being new, what makes these
buoys so special? They carry an impressive
array of equipment powered by a combination
of solar and wind energy. This variety of
instrumentation – which we’ll look at later –
and their flexibility make the buoys unique.
But their other star quality is their ruggedness.
This is crucial because conditions in the
English Channel are harsh, with waves up to
6m, strong winds and a high volume of boat
traffic. In short it’s hostile and busy, causing
serious logistical problems for long-term buoy
deployments.
Standard environmental monitoring buoys
used around the world would simply not be
up to it, so we went back to the drawing board
to create something new. We worked with
Plymouth company Hippo Marine to design
and build the new buoys to withstand the
Channel’s tough conditions, while enabling the
equipment to take the sensitive measurements
needed. Integral to the design is a ‘moon pool’
– an enclosed column of water at the centre of
the buoy which enables the instruments to be
lowered into the sea and remain submerged and
working while being completely protected.
Each of the buoys weighs around 3.5 tonnes
and requires 6 tonnes of anchorage to keep
it in place. To add to the challenge, they also
have to be kept on station and facing in a
constant direction, to ensure the solar panels are
oriented efficiently and the optics equipment is
unshaded.
It hasn’t all been plain sailing. We really were
The possibility of a
7m buoy running
amok in one of
the world’s busiest
shipping lanes
was not to be
contemplated lightly.
at the mercy of the elements when it came to
getting the buoys to their stations, and on more
than one occasion the deployment mission
had to be aborted as the weather deteriorated.
Tethering the buoys was also quite a challenge
– the possibility of a 7m buoy running amok
in one of the world’s busiest shipping lanes was
not to be contemplated lightly, as we’d learned
from experience. Even with all its heavy-duty
tethering, the L4 buoy decided to make a break
for a nearby beach during a test run in 2008. Following this the entire system was refined and
improved, so our buoys can hopefully stand up
to anything the Channel will throw at them in
the years to come.
Down to the detail
We can use the long-term data collected by
boat to establish a baseline for studying how
humans are affecting the oceans and the planet
through climate change. For example, changes
in temperature affect ocean chemistry and cause
variations in the make-up of the biota – the
plant and animal life. With the buoys now
fully operational, we also have high-frequency,
small-scale data, which lets us look at shortterm changes and see how they in turn affect
the longer-term trends. All this gives us a much
greater understanding of our coastal waters.
Take plankton blooms, for example, which
can appear within hours and spread and die
within days. Blooms are important because
they may concentrate food fish, for example,
which could be a boon to fishermen – or
concentrate toxins – ‘red tides’ that are a threat
to shellfisheries. So we need to understand
what causes these blooms and why a particular
species appears one year and maybe not the
next.
Small changes in the physics or chemistry
of the sea may hold some of the answers, but
it is likely to be a complex combination of
factors. Our sensors are measuring temperature,
salinity, nitrate levels, sediment concentrations
and chlorophyll. They also measure coloured
dissolved organic material, which can ‘stain’ the
water, reducing the amount of light available for
photosynthetic phytoplankton and interfering
with satellite readings of things like sea-surface
temperature and phytoplankton concentration.
There’s even a weather station and camera on
board. By studying these factors we can begin
to understand how changes in the environment,
temperature and nutrient availability, for
example, affect the marine ecosystem on
an hourly basis, giving us the potential for
predicting the onset of phytoplankton blooms.
The L4 buoy has already given us information
on the influence on phytoplankton of freshwater surges resulting from flood conditions
in the River Tamar. These ‘freshening’ events
brought extra nitrates into the sea from river
run-off, and resulted in blooms at a time
when conditions were otherwise unsuitable for
accelerated plankton growth. We’d had our
suspicions about this for many years but until
now had not been able to recover any evidence
on our weekly sampling visits.
Put this small-scale detail together with
PML’s expertise in ecosystem modelling,
remote sensing, and our existing weekly
in-situ observations, and you get some very
useful insights into what is happening in the
English Channel. This level of detail will
directly support decisions about the sustainable
management of our coastal and shelf waters.
Not only that, but as different questions about
the chemistry and physics of the sea arise and
new methods of study are developed, our
buoys are flexible enough to accommodate
new instruments to provide the data needed to
respond.
One could be forgiven for thinking that the
data buoys’ hourly readings, combined with
broad-scale satellite readings, would make
boat visits redundant. This is not the case; we
still need other readings and water samples for
analysis in the lab, because the deeper water
column still eludes the satellites and the data
buoys’ instruments. But before 2009 we had
only part of the story: now we have boat, buoy
and satellite working together to give us the
complete picture.
FURTHER INFORMATION
The buoys were funded through NERC’s Oceans
2025 initiative, which is implemented through seven
leading UK marine centres. www.oceans2025.org
Dr Tim Smyth is manager of the data buoy project at
PML. Email: [email protected]
Kelvin Boot is science communicator at PML.
Email: [email protected]
Western Channel Observatory
www.westernchannelobservatory.org.uk
Planet Earth Autumn 2010
23
New techniques let scientists analyse ancient footprints
to understand how our forebears’ physiques and
lifestyles changed over time. Matthew R Bennett, Robin
Huw Crompton and Sarita Amy Morse describe recent
breakthroughs in the science of fossilised movement.
Tracking our
ancestors
A
key part of being human is our
‘bipedal’ posture – we walk upright
on two legs. The development of
bipedalism was a critical stage in our
evolution. Another was the later transition from
early habitual bipeds such as Australopithecus
africanus, made famous by the skeleton ‘Lucy’,
to more modern humans like Homo erectus and
Homo sapiens, which were, and are, endurance
walkers and runners.
Our ancestors’ ability to walk efficiently
influenced how they foraged and hunted for
food, how they gathered raw materials for
tools and how they migrated across the globe.
But despite more than a century of research,
our understanding of the modern foot is still
relatively poor, and our knowledge of our
ancestors’ feet is even more uncertain.
The foot is a complex structure of 22 bones
held in place by a lattice of soft tissue. It
interfaces with the ground to create pressures
which decelerate, balance and accelerate the
body during walking and running. Little
wonder this complex machine has not given up
its secrets easily.
Fossil foot bones are rarely found with
skeletons of known species, and the fossil record
is fragmentary. When we do find part of one
of our ancient ancestors’ feet, it has usually
been badly chewed by scavengers. And fossil
foot bones rarely give a definite indication of
how our early ancestors walked, since they act
24 Planet Earth Autumn 2010
through a series of complicated soft tissues
which are rarely preserved – from ligaments to
the outer skin – so they interact only remotely
with the ground.
Fossilised motion
We believe human footprints provide a better
record of our ancestors’ feet than foot bones – a
record of ‘fossilised motion’ formed as they
walked across soft ground. The prints directly
record the forces our forebears applied to the
ground to balance and propel their bodies.
Our team is a collaboration between field
animal footprints were thought to be rare
in the geological record – freak occurrences
of sedimentary preservation, with each
one holding a rare glimpse of locomotive behaviour. But we’re coming to realise that
footprint sites probably aren’t so scarce; it’s just
that they haven’t been properly identified and
analysed before.
The oldest and most famous ancient
footprints are at Laetoli in Tanzania, made
some 3.75 million years ago by an ancestor
similar to ‘Lucy’ (Australopithecus africanus).
Last year we published in Science details of the
second-oldest human footprint site,
found in northern Kenya, dating
from 1.5 million years ago.
We think these footprints were
made by Homo erectus, one of
the first of our ancestors capable
of long-distance walking and
running. Comparing these sites
and prints will help us understand
the transition in locomotive
style between species of Australopithecus and
Homo. There are also other more recent human
footprint sites around the world, and lots still
to be discovered, with prints made by Homo
sapiens in diverse settings like coastal mudflats,
caves and layers of volcanic ash.
These sites help us understand the data on
‘fossil locomotion’ from ancient footprints.
For example, some team members have just
We believe that human
footprints provide a better
record than foot bones of
our ancestors’ feet.
scientists at Bournemouth University led by
Professor Matthew Bennett, who have expertise
in excavating and recording footprints, and
experts in biomechanical modelling at the
University of Liverpool under Professor Robin
Crompton. Our goal is to meld field science
with computational analysis and simulation to
reveal the fossilised motion of our ancestors.
Until relatively recently, human and
tracking our ancestors
Matthew Bennett and the team scanning footprints at Ileret, Kenya.
returned from Namibia, where one of the
richest footprint sites in the world recently
came to light. The site contains many human
trails and a plethora of animal prints including
elephants, giraffe, buffalo, cattle, goats/sheep
and a range of birds. The site is in a large dune
field, and each day the team used quad bikes
to reach it – a former mudflat over which the
dunes have migrated. The footprint surfaces
are only exposed for a few years at a time as
they are revealed and then covered again by the
mobile dunes.
The site’s age will not be known until the
results of our dating programme are completed
later this year, and it is probably only a few
thousand years old. But it contains important
information to help us interpret ancient
footprints, since the prints reveal the subtle
influence of the surface they are made in. In
one case there is a trail of more than 70 prints
formed by an individual walking across a
shallow channel and mudflat. The individual
prints vary in their anatomy and with the type
of sediment they were made in, particularly its
moisture content. Adding sites with different
properties to our database of knowledge is
crucial if we want to understand the patterns
of foot pressure caused by different styles of
locomotion and foot anatomy. The team will
also be returning to northern Kenya and the
second-oldest footprint site in the coming year
to continue excavating these ancient prints.
3-D scans of a human footprint from Formby, UK (left), c3500 years old, and one of the
prints from the quarry at Valsequillo, Central Mexico.
Capturing the information held in a
footprint has long involved casting it in a
medium like latex or plaster, a destructive
process that does not readily provide
quantitative data that we can analyse
objectively. Our team has pioneered the use of
an optical laser scanner to capture footprints
in the field. Mounted on a custom-made rig
which controls light and dust levels, the laser
scanner provides digital elevation models of
individual prints that are accurate to less than
a millimetre. The scans record each print,
preserving them for the scientific community
even if these fragile sites with their prints
erode in future. More importantly, the scans
provide the basis for statistical analysis of print
anatomy.
One of our goals is to develop objective
methods for interpreting footprints. First, we
needed to be able to tell for sure whether or
not a mark in the ground is really a human
footprint. Working at controversial sites in
Mexico, and closer to home in South Wales, we
have developed a simple numerical test using
scans of footprints of various ages and species,
formed in different materials.
Objectivity is critical, especially as prints
within a single trail may vary from one another;
we need a way of effectively determining what
the mean print looks like, eliminating the bias
associated with the interpretation of individual
prints. Professor Crompton’s team did some
lateral thinking and realised that methods
used to analyse chemical patterns in the brain
are also ideal for comparing footprints. They
have developed a new approach which lets us
calculate an ‘average’ footprint from a whole
trail, and then compare it statistically to other
print populations.
This lets us objectively compare prints made
by different species at different times and helps
develop models of how human locomotion
has evolved. For example, the technique has
helped resolve a 30-year debate over the Laetoli
footprints, showing they were made not by a
creature that walked with bent hips and knees,
but by a more modern version with a gait not so
far from our own.
Studying these footprints has greatly
improved our knowledge of our ancestors. We
can more accurately place them on the map
chronologically, see what fauna they interacted
with – even make them walk through computer
modelling. We can’t research our forebears’ feet
directly, but our work may ultimately mean the
prints they left behind are just as good.
More information
Matthew Bennett is Professor of Environmental &
Geographical Sciences at Bournemouth University.
Robin Huw Crompton is Professor in the Institute
of Ageing and Chronic Disease at the University
of Liverpool. Sarita Amy Morse is a student of the
anthropology department at Rutgers, State University
of New Jersey.
Email: [email protected]
Planet Earth Autumn 2010
25
Hot off the press
Signs of the forces that shaped the Earth’s surface are all around us; to
the trained eye, each rocky outcrop tells a story about how the landscape
developed over millions of years. But when it comes to understanding what’s
going on in the hot depths hundreds of kilometres below, or how the planet
first condensed out of celestial dust, things get trickier. Tom Marshall reports.
P
rofessor Bernie Wood carefully fits a
tiny sliver of sample material into a
giant piece of machinery hulking to
one side of his lab, tucked towards the
rear of Oxford University’s Earth Sciences
faculty building.
It’s a delicate business. One mistake and
he’ll know about it only when he removes his
sample several hours later and finds something
broke under the strain.
Wood and his team want to understand
problems like how the Earth and the other
planets of the solar system formed, and how
our planet’s core then separated from its silicate
mantle when the planet was still young.
They go about finding out by feeding
mineral samples into huge machines to
compress them. Biggest of all is the multi-anvil
press; it applies hundreds of thousands of times
the pressure at the Earth’s surface for several
hours, while creating scorching heat with an
electrical current.
It’s a unique, custom-built piece of kit. As
well as replicating the conditions deep inside
the Earth, it can supply enough pressure to
turn graphite into diamond. There are only a
few working in the UK – apart from the one
at Oxford, there are others in earth sciences
departments at Bristol, UCL, Edinburgh and Cambridge.
The team makes a lot of its own equipment.
Experimental petrologists have to be good in
the workshop; their equipment needs bespoke
components that you can’t buy on the high
street, and the whole team can wield a mean
lathe when the situation calls for it. ‘We build
26 Planet Earth Autumn 2010
hot off the press
Brandon Alms/istockphoto.com
most of the parts for our machines ourselves,’
says postdoctoral researcher James Tuff. ‘This
is very much hands-on, make-your-own-rocks
geology.’
At the heart of the press is a cubic
arrangement of tungsten carbide cubes – the
‘anvils’. Each is missing a corner. Powdered
samples are encased in an octahedral medium
designed to transmit pressure and fitted with
a tiny graphite or semi-conducting heating
element together with a thermocouple that
records what happens as the heat and pressure
mount; the octahedron fits snugly into the gap
left at the centre of the cube of cubes by their
missing corners.
Once activated, the hydraulic press bears
down with a load of up to 1000 tonnes, and
the anvils transmit this load into the sample
along each of its faces. It’s compressed from all
sides at once, while an electric current heats up
the furnace element to thousands of degrees.
A thick outer metal ring would protect those
nearby if anything gave way under the titanic
pressure.
Once pressurised, each sample may be left
for several hours, then allowed to decompress
to relieve the pent-up stress within the anvils.
Sometimes everything works; sometimes the
heating element burns out, or one of the anvils
breaks, or something else goes wrong, and
everything must be repeated. But this kind of
work, known as experimental petrology, has
laid the foundations on which much of our
modern understanding of geology is built.
Professor Wood’s group’s current research is
to recreate the conditions under which Earth
accreted – formed out of clouds of dust in
space – as well as those still found deep beneath
our feet, with a combination of precision
engineering and brute force.
Seismologists can tell a lot about the Earth’s
interior from how sound moves through it,
and we get clues to its chemical make-up from
samples brought to the surface by drilling
or tectonic movements. But experimental
petrology is the only way to test theoretical
models of the deep Earth and understand how
minerals behave in extreme conditions.
‘The deepest borehole we have (Russia’s Kola
superdeep borehole) only goes down about
12km,’ explains postdoctoral researcher Jon
Wade. ‘But the mantle begins far beneath
that and the core-mantle boundary doesn’t
start until 2900km down. So our knowledge
of the deep Earth is mostly inferred from
seismic data or from rare rocks brought to the
surface by tectonic and volcanic activity. Using
experimental techniques we can often test many
of these inferences.’
False-colour image of the results of a run on the multi-anvil
press at pressures equivalent to 800km beneath the Earth’s
surface, taken using a scanning electron microscope. The
circular shape in the middle is perovskite, a silicate mineral
thought to be dominant in the lower mantle; the yellow spots
are iron.
The team use their press to simulate
conditions down to around 660km deep –
around where the upper and lower mantles
meet. At this depth, the pressure is around 20
gigapascals – some two hundred thousand times
the pressure at the surface – and the temperature
around 2000°C.
Other presses exist that can simulate even
deeper conditions, but at these depths the
discipline comes up against the physical limits
of the materials. ‘The problem is that to work
with reasonable samples at this kind of depth,
you need an absolutely enormous press,’ Wood
explains. ‘Beyond certain depths, you just can’t
build a machine that can compress the sample
That’s because the elements in the material of
the primitive Earth were divided up unequally
when it separated into its present parts.
Rock-loving, or ‘lithophile’, elements were
concentrated disproportionately in the silicarich mantle, while metal-loving ‘siderophile’
elements mostly ended up in the iron core.
More than 99 per cent of the Earth’s total
gold supply is locked up in its core, for example.
This is why gold is so rare and valuable.
Otherwise, there would be enough in the upper
Earth to cover the planet’s surface to a depth of
nearly half a metre.
This process is called ‘partitioning’, and
scientists are striving to understand the
chemical and thermodynamic processes
involved. They rely on the decay of radioactive
elements into other ‘daughter’ elements with
differing preferences for either the rocky mantle
or metallic core to shed light on the timescales
over which the planet formed. But to test how
element partitioning varies within a growing
planet experimentally takes huge temperatures
and pressures. Hence the presses.
Experimental data has let Wood and his
team build models that simulate partitioning
far more accurately than was previously
possible. By running experiments and carefully
controlling pressure and temperature, they
can begin to understand the conditions under
which the Earth’s core must have formed.
‘You don’t get the current concentration
of, say, nickel and cobalt unless you assume
equilibration of metal
and silicate at very
high temperatures and
pressures,’ Wade says. ‘So
we know that the core
and mantle must have
reached equilibrium at
the base of an ocean of
magma around 700 kilometres deep.’
The results don’t just apply to Earth’s history;
they shed light on how all planets formed,
condensing out of clouds of gas and gradually
separating into core, mantle and crust. Samples
go into the press as homogeneous powder;
under the forces and temperatures they face
there they swiftly divide into their component
parts, forming metallic core and silicate mantle.
‘We want to find the effects of temperature,
pressure and chemistry on the components of
planetary formation,’ says Wood.
‘Each sample we work with is like a
simulated planet a few millimetres across,’
explains Tuff. ‘You’ve got a metallic core
surrounded by silicates, and we’re subjecting
them to conditions that they may well have
experienced when the Earth was being formed.’
Each sample we work with is
like a simulated planet a few
millimetres across.
enough.’ Alternative approaches, like using
diamond anvils, can take more pressure, but
have their own drawbacks.
Little planets
One of the greatest challenges for experimental
petrologists is understanding how the Earth
formed, and how the elements were divided
between its core, mantle and crust.
We know the overall chemical make-up of the
Earth; it’s similar to the mix of elements found
in meteorites known as carbonaceous chondrites.
These are made of the same primitive stuff that
formed all the solar system’s planets.
But the breakdown of the Earth’s mantle
doesn’t match that of the meteorites – for
instance, in comparison to chondrites, Earth’s
silicate mantle has less iron and nickel.
Planet Earth Autumn 2010
27
When politics
and science come
face to face
Relations between the
worlds of science and politics
are rarely straightforward.
Former NERC policy intern
David Ferguson (above) tells
us just how tricky, and how
important, the relationship
can be.
28 Planet Earth Autumn 2010
P
olicy-makers want definite answers,
scientists prefer probabilities; the
evidence says one thing, the political
ideology another. Such scenarios are all
too common. The recent volcanic ash crisis is a
good example of scientific advice being subject
to intense outside pressures, and also how such
advice can have profound economic and social
implications.
Science-based high-tech industries are
increasingly important to the UK economy. How
far is the government responsible for developing
such sectors? How can they know which fields
will be economic winners? Where is the dividing
line between the responsibilities of the public
and private sectors in creating the technology
and jobs of tomorrow?
The House of Commons Select Committee
on Science and Technology (S&T) is one of
the main forums where questions like these are
publicly debated. The committee comprises a
cross-party group of UK MPs with a broad remit
to investigate scientific issues across government,
and it often acts as referee to public disputes on
scientific issues. The committee’s regular public
meetings routinely bring together research
scientists, policy-makers and regulators, who give
their views and account for their actions on an
array of science-related topics. As a NERC PhD
policy intern at Westminster I recently got the
chance to experience the committee’s work at
first hand.
You might reasonably ask why anyone
would swap their research into volcanism in
northern Ethiopia for a suit and the corridors
of Whitehall. But I’ve always been interested in
what happens to science beyond the laboratory
door. When the NERC parliamentary internship
came up I grabbed the chance to see for myself.
Fortunately the Ethiopian volcanoes at least
stayed quiet while my attention was diverted!
Both houses of Parliament have to scrutinise
the government’s activities, and one of the
key tools in this work is the select committee,
a subject-specific group of Members with
statutory powers to investigate and question
government ministers and public figures on
their policies, actions and intentions.
The S&T Committee tackles a particularly
large array of subjects, from the fiscal
management of UK research councils and the
licensing of stem-cell research to the culture of
‘evidence-based policy’ within Whitehall – any
topic with a scientific dimension is open to
its investigation. Without firm ties to any one
government department, the committee is free
to navigate almost the entire policy landscape.
While I was in Westminster I took part
in a number of inquiries, including several
ad hoc investigations launched in response
to emerging events. Some of these were
particularly relevant to NERC science, such
as the impact of potential spending cuts on
UK research budgets, the global regulation of
geoengineering (an inquiry held jointly with
a US Congress committee) and the disclosure
of emails from the Climatic Research Unit at
the University of East Anglia (the so-called
‘Climategate’ affair).
The focal point of a committee’s weekly
diary is the evidence session. During
these public meetings, witnesses come to
Westminster to answer questions and make
statements. Over the course of my three-month
internship, more than 35 witnesses appeared
in front of the S&T Committee, representing
a cross-section of those who fund, regulate, use
and carry out science.
The sessions varied from informationgathering to direct interrogations of someone’s
actions or views, and the tone differed
accordingly. It was fairly common to have some
when politics and science come face to face
quite animated exchanges – though these were
mostly reserved for sparring with politicians,
well versed in the artful avoidance of difficult
issues. I quickly learned that a hostile question
can be very effective against a seasoned
government minister but is liable to send most
(though not all) academics into a rambling
panic.
The evidence from these sessions forms
the basis of the committee’s reports; official
documents published by the House of
Commons and presented to the government,
which has an obligation to respond. As my
internship coincided with the last months of
the parliamentary session, there was a push to
achieve as much as possible before the election.
For the committee and its staff this meant a
non-stop schedule of drafting reports, public
evidence sessions, press briefings and oftenlengthy private meetings to debate the details
of inquiries and their final reports.
One of my main tasks was to help draft
a report on the committee’s impact since its
inception in 1966. The Legacy Report was the
last report published by the committee before
the 2010 general election. Facing an uncertain
future, the committee was understandably
keen to highlight the benefits of its work. I
had to trawl the parliamentary archives for
committee documents and talk to former
members to get their perspective, which gave
me a great overview of the contribution the
committee has made.
During all this I still found time to ‘tweet’
updates on my Westminster life (on the ‘microblogging’ website Twitter). Though I did have
to exercise a certain degree of discretion, to
avoid breaking press embargoes or breaching
There’s a huge and
under-exploited
opportunity for
research scientists to
get out of the lab.
the trust of being included in private
parliamentary discussions.
Beyond their primary responsibilities,
NERC interns are also encouraged to
experience as much of Westminster life
as possible and have access to most of the
Westminster estate. Between committee
meetings and report writing I managed to
fit in a visit to a theatrical Prime Minister’s
Questions; several science-policy related debates
and seminars held around Westminster; a tour
up the clock tower (with earplugs included)
to hear Big Ben strike midday; and plenty of
Westminster’s favourite pastimes – spotting
famous MPs and ministers in the canteen and
coffee shop and guessing the party affiliation
of groups of young researchers in the House of
Commons bar.
How will science scrutiny fare in the new
Parliament? When the House of Commons
is disbanded prior to a general election, so
too are all of its attendant committees, and
they, like their respective members, have no
guarantee of surviving the electoral process. As
my internship came to an end, the committee
members and their staff had no idea if the final
report of that parliamentary session would also
be the committee’s very last.
As it turned out, the committee was reestablished, and is now chaired by Labour MP
Andrew Miller. As it retains only one of its
former members, though, it’s likely to have a
very different character from its predecessor.
My experience has certainly broadened my
perspective on the role of science in wider
society, and the value of original research in
developing good policy. Equally enlightening
was seeing how scientific research can become
highly politicised – as with climate science
currently. Such debates need engaging
and charismatic scientists who can clearly
communicate the scientific viewpoint.
I also saw that there’s a huge and underexploited opportunity for research scientists to
get out of the lab. Anyone can submit written
evidence to a parliamentary committee inquiry,
and those with relevant expertise may be invited
to give evidence directly to Parliament. If
scientists don’t speak up on issues relevant to
them, someone else can, and probably will.
Further information
David Ferguson is a volcanology student at the
Department of Earth Sciences, University of Oxford.
Email: [email protected]
Thanks to Chris Tyler, Xameerah Malik and Glen
McKee at the House of Commons, and to NERC for
funding the internship.
Planet Earth Autumn 2010
29
Mysteries of the
blue ocean
Scientists used to think
the open ocean was a
watery desert. Now we’re
starting to understand the
diversity of life there and
the profound influence it
has on our climate. Types
of plankton that were once
dismissed turn out to play a
vital role in the carbon cycle.
Dave Scanlan and Mike
Zubkov explain.
Microscope image of a 3μm alga of the
class Prymnesiophyceae. Green areas are
caused by genetic markers tailored to this
group; the cell’s nucleus fluoresces red.
30 Planet Earth Autumn 2010
L
ife in the oceans evokes a plethora of images – from whales and
shoals of tropical fish to spectacular coral reefs and even monsters
of the deep. But although these might be the most amazing and
colourful of marine spectacles, it is the abundant microscopic life
beneath the waves that ultimately drives all the biogeochemical cycles of
the oceans and hence of our planet.
The sunlit portion of the ocean, the so-called photic zone, is where
carbon is ‘fixed’ – turned into an organic form that living things can
use – by photosynthesis, so it is critical to the global carbon cycle. At the
core of the marine food chain tiny phytoplankton, fated to move around
the globe at the whim of ocean winds and currents, are the major fixers
of carbon dioxide (CO2), levels of which have increased markedly over
the last 100 years because of human emissions. To get an idea of how
important these organisms are on a global scale, remember that 40 per
cent of the CO2 fixed on Earth occurs in marine systems, and 75 per cent
of this is fixed in the open ocean.
We should remember that this is just the current thinking, though. Up
until the late 1970s the open oceans were thought of as biological deserts,
and we knew little of the abundance and diversity of microbes that are
now known to exist there. Within the last 30 years we have identified and
characterised the two main genera of cyanobacteria, Prochlorococcus and
Synechococcus, often misleadingly called ‘blue-green algae’ because they
photosynthesise like plants. Because of this, we have begun to radically
rethink how marine food webs function.
Depending on the exact structure of this picophytoplankton
community (that is, phytoplankton a few micrometres (μm) in size)
and its diversity, the ocean’s whole food web may shift from one state
to another. For example, dominance of the very small Prochlorococcus
(0.6μm) may indicate that mineral elements are being recycled very
efficiently and that very little organic carbon is sinking down from sunlit
waters, while dominance of the larger Synechococcus (1μm) may show
that more organic carbon is sinking because mineral nutrients are being
recycled less efficiently.
mysteries of the blue ocean
Peeking into the microbial black box
Until now, these cyanobacteria have been
thought to dominate carbon fixation in the
open ocean. However, the photic zone also has a
high biomass of small eukaryotic phytoplankton
– that is, photosynthesising plankton with a
complex cellular structure – which are capable
of CO2 fixation. The eukaryotic phytoplankton
community has long been a ‘black box’ – we
have known little of its composition or of its
contribution to CO2 fixation. It is only by
determining how much CO2 these different
groups fix into biomass that we can get a full
understanding of the Earth’s carbon cycle.
Ascertaining this contribution has been a
thorny problem for biological oceanographers
for decades. However, using flow cytometry – a
technique borrowed from medical research that
can physically separate (and hence ‘sort’) cells
west Africa. This suggests they play a key role
in global CO2 fixation, though this needs to
be confirmed by widespread sampling from
other parts of the world’s oceans – our Atlantic
Meridional Transect research is under way.
One of the best-known prymnesiophytes
is Emiliania huxleyi, a species that can form
extensive blooms in some regions and is
characterised by its chalk-like shell of calcium
carbonate, the so-called coccolith. The
prymnesiophytes we observed in our study,
however, are likely not calcified as shown both
by examination under the microscope and by
flow cytometry. This reinforces the idea that
these prymnesiophytes include previously
undiscovered groups.
It is likely that some of the organic carbon
of these prymnesiophytes and other eukaryotic
phytoplankton eventually sinks down from
the photic zone to the
deep ocean, rather
than being returned
to the atmosphere as
CO2. Given their clear
importance in this
marine ‘biological carbon
pump’, it is crucial that
we discover the factors
that control the growth
of small eukaryotes in the
oceans.
Certainly, being able
to make more accurate predictions of the effects
of global warming on our planet will probably
depend on what we learn about carbon cycling
by these organisms. Mathematical models for
predicting CO2 drawdown by the oceans are
currently quite simple, yet the biology may be
much more complicated.
For instance, it is wrong to assume that the
salty waters of the sea are uniform throughout.
Light penetrates only the top 200 metres of
the ocean, and during the summer months the
water column becomes stratified, separating
the nutrient-rich deeper waters from the windmixed surface layer.
Microbial activity quickly depletes the
nutrients in the surface waters, and specific
niches become defined: surface waters that
are high in light but low in nutrients, and
deep waters that have little light but are
rich in nutrients. We now know that such
environments favour specific genotypes or
‘ecotypes’ that are adapted for life in these
different niches and have different cell-specific
CO2 fixation rates. We need to take this into
account when evaluating the ocean’s CO2
sequestration and productivity.
The future offers much. Picophytoplankton
Picophytoplankton may not
be the most visible of the sea’s
inhabitants but they are vital,
fuelling much of the global
marine production of biomass.
based on their size and fluorescence properties
– we have now been able to measure how much
CO2 is being fixed by different phytoplankton
groups.
Analysing samples collected from surface
waters during a research cruise aboard RRS
Discovery in the subtropical and tropical
north-east Atlantic Ocean we discovered
that eukaryotic phytoplankton actually fix
significant amounts of CO2, contributing
up to 44 per cent of the total, despite
being a thousand times less abundant than
cyanobacteria. This is probably because
eukaryotic phytoplankton cells, although
still small, are considerably bigger than
cyanobacteria.
Two groups of eukaryotes were distinguished
by flow cytometry, ‘EukA’ cells being more
abundant but smaller than ‘EukB’ cells.
Molecular techniques revealed that EukB
were mostly photosynthetic organisms called
prymnesiophytes, most of which have never
been cultured in the laboratory. Many of these
are probably previously unknown species. These
prymnesiophytes accounted for as much as 38
per cent of CO2 fixation in the (sub)tropical
north-east Atlantic Ocean, off the coast of
A water sampler being launched from the RRS Discovery.
may not be the most visible of the sea’s
inhabitants but they are certainly vital, fuelling
much of the global marine production of
biomass. Indeed, it was not so long ago that
oceanographers missed these tiny cells simply
because they were too small to be caught in
the large pore-size meshes traditionally used
to collect phytoplankton samples. But without
them, the oceans really would be watery deserts,
and our world would be a very different place.
Just how important they really are may become
even more apparent in the coming years.
More information
Dave Scanlan is Professor of Marine Microbiology
at Warwick University. Professor Mike Zubkov
is a member of the marine biogeochemistry and
ecosystems group at the National Oceanography
Centre. Email: [email protected] or
[email protected]
Further reading
Jardillier, L, Zubkov, MV, Pearman, J, Scanlan,
DJ (2010). Significant CO2 fixation by small
prymnesiophytes in the subtropical and tropical
northeast Atlantic Ocean. The ISME Journal:
International Society for Microbial Ecology.
doi:10.1038/ismej.2010.36
Planet Earth Autumn 2010
31
Website rocks
Geology for the people
Need information about the Earth beneath your feet? Seeking
nourishment for budding young scientific minds? Looking
for photos of the landscape around you? Now there’s
one place to find them all: the British Geological Survey’s
‘OpenGeoscience’ website. Richard Hughes sells it to us.
L
aunched in early December 2009, OpenGeoscience is unique. It
gives visitors access to their choice of a wide range of geological
data, searchable maps, high quality photographs, Key Stage 1-3
resources, in-house software applications, and an open archive of
BGS reports and published papers. What’s more, for most users it’s free.
The site’s flagship is access to street-level-resolution geological mapping
for the whole of the UK – the first service of its kind in the world. Visitors
can access the maps through a purpose-built ‘UK geology viewer’, which
allows them to zoom into their area of interest and view the geology
against a topographical (landscape) map or satellite image backdrop. Click
on the map and detailed geological information will appear before your
eyes. More technical users can export the dataset to a KML file (a file
type used to display geographic data in a geo-browser) and look at it on
GoogleEarth, or view it as a web map service.
The image library – GeoScenic – has more than 50,000 modern and
historical images from BGS’s archives, which you can search by theme,
collection, or even the name of your town or village. It’s proving extremely
popular with teachers as a way of illustrating their lessons.
Then there’s the ‘popular geology’ resources, which include BGS’s
highly successful schools seismology project, and a ’download and cut-out’
model of the ash-producing Icelandic volcano Eyjafjallajökull.
While it’s simple for the user, there’s some sophisticated software
working hard behind the scenes. Because the maps can be delivered via
KML files and web map services it’s possible to ‘mash’ them with data
from entirely different sources. Mash-up applications have real scientific
value. A good example is the recent map of the land-cover history and
surface geology of East Anglia since the Domesday Book, which was
based on BGS superficial and offshore geology, selected land-cover
data, administrative and geographic boundaries from Ordnance Survey
OpenData, and global coastline data from the US National Oceanic and
Atmospheric Administration (see www.giscloud.com/map/3186/medievalfenlands/land-cover-history).
32 Planet Earth Autumn 2010
The response to OpenGeoscience has been astonishing. The launch got
widespread media coverage – even knocking the Copenhagen climate
summit off the BBC Science and Environment website’s top spot at one
point. On launch day our map server was delivering over 1,000 files per
second, and the BGS website received three times its regular traffic during
that month. But why?
There are lots of reasons, some of them fairly obscure to the average
visitor. The geospatial information industry likes it because web
mapping demonstrates the usefulness of web standards applications. The
European Commission approves because it complies with the INSPIRE
environmental information directive, now part of UK law. The research
and education sectors like it because of the free resources it puts at their
disposal. Dr Steve Drury, Senior Lecturer in Remote Sensing at the Open
University, foresees the website will become ‘a kind of “GoogleRock” for a
great many people’.
The public likes OpenGeoscience because it brings information about
UK geology into their homes in a way that’s just not been possible before.
And BGS likes OpenGeoscience too. The website has raised the
visibility of BGS and NERC science and that’s always a good thing. But
its success also demonstrates that there’s a nation of users out there hungry
for online information about their ‘place’. Try it for yourself, and find out
what’s beneath your feet.
Further information
Richard Hughes is Director of Information and Knowledge Exchange at BGS.
Email: [email protected]
Access OpenGeoscience at: www.bgs.ac.uk/opengeoscience and tell us what
you think. Email: [email protected]
WEBSITE ROCKS
Screen shots from the GeoScenic website at
www.bgs.ac.uk/opengeoscience
www.giscloud.com/map/3186/medieval-fenlands/land-cover-history
Planet Earth Autumn 2010
33