A course sponsored by the South
African National Antarctic
Program (SANAP) as part of the
TRAIN-SOPP project and
prepared in collaboration with
the Marine Research Institute
(UCT)
Understanding Ocean and Earth
System Science through models
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Understanding the contemporary Earth System Science
relies on the recruitment and formation of a generation of
young scientists with the capabilities to analyze the products
of climate and Earth System Models.
Capacity building in human and technological resources
should be an integral component of the curriculum. This
should go beyond the traditional boundaries of the scientific
disciplines taught at universities.
We target undergraduate and early graduate students from
Science, Engineering and Economics faculties in South
Africa, which provide introductory courses in Information
Technology, Computing, Applied Mathematics, Physics,
Chemistry and Earth Sciences.
AGENDA
—  Lectures
—  10h30-11h30 Enrico Scoccimarro
ESM crash course part 1: the physical components
—  11h30-12h30 Marcello Vichi
ESM crash course part 2: the carbon cycle
—  12h30-13h30 Break
—  Hands-on session
—  13h30-15h00 Group A
—  15h00-16h30 Group B
ESM crash course part 2:
the carbon cycle
A/Prof Marcello Vichi
University of Cape Town
Dept. of Oceanography
Director of the Marine Research Institute
[email protected]
… So it happens, that every element says
something to someone, like the mountain
valleys or beaches visited in youth. "
5
One must make an exception for
CARBON, because it says
everything to everyone, that is, it
is not specific. …"
PrimoLevi(1919-1987)
Featuring:
Our character lies for
hundreds of millions of
years, bound to three
atoms of oxygen and one
of calcium, in the form of
limestone: it already has a
very long cosmic history
behind it, but we shall
ignore it. […]
Soft white limestone
formed when windblown dunes made of
shell sand were
hardened into rock in
the late Cretaceous
on the southern coast
of South Africa.
https://www.earth.ox.ac.uk/
~oesis/field/
Thetalebegins…
But, precisely for the good fortune of the narrator, whose story
could otherwise have come to an end, the limestone rock ledge of
which the atom forms a part lies on the surface. It lies within
reach of man and his pickax […] at any moment - which I, the
narrator, decide out of pure caprice to be the year 1840 - a blow of
the pickax detached it and sent it to the lime kiln […] it was
roasted until it separated from the calcium, which remained so to
speak with its feet on the ground […]. Still firmly clinging to two
of its three former oxygen companions, it issued from the
chimney and took the path of the air.
Its story, which once was immobile, now turned tumultuous.
Atmospheric Infrared Sounder (AIRS)
instrument on NASA's Aqua
[The carbon atom] was caught by the wind,
flung down on the earth, lifted ten kilometers
high. It was breathed in by a falcon,
descending into its precipitous lungs, but did
not penetrate its rich blood and was expelled.
It dissolved three times in the water of the
sea, once in the water of a cascading torrent,
and again was expelled.
Ocean
AcidificaCon
There is very high certainty
that sea water chemistry is
changing due to rising
atmospheric CO2, and that
human activities are the root
cause.
Consequences on marine
ecosystems are still
unpredictable
pH
decrease
Exoskeleto
n
weakening
from “Ocean Acidification: questions answered”
Shell
dissolutio
n
Atumultuous“natural”story
Our character, the carbon atom, is now (but it always was…) part of a cycle, the
natural carbon cycle of the Earth System. Primo Levi’s literary dream goes on…
…. is the destiny of wine
to be drunk and the
destiny of glucose to be
oxidized…
Backtotheair:onepossiblepathway
… was dragged by the bloodstream all
the way to a minute muscle fiber in the
thigh, and here brutally split into two
molecules of lactic acid, the grim
harbinger of fatigue: only later, some
minutes after, the panting of the lungs
was able to supply the oxygen
necessary to quietly oxidize the latter.
So a new molecule of carbon
dioxide returned to the
atmosphere
…. the parcel of the energy that the sun had handed to
the vine-shoot passed from the state of chemical energy
to that of mechanical energy, and thereafter settled
down in the slothful condition of heat, warming up
imperceptibly the air moved by the running and the
blood of the runner.
0.03%
…. Carbon dioxide is the aerial form of the carbon of which we have up
till now spoken: this gas which constitutes the raw material of life, the
permanent store upon which all that grows draws, and the ultimate
destiny of all flesh, is not one of the principal components of air but
rather a ridiculous remnant, an 'impurity', thirty times less abundant than
argon, which nobody even notices.
… from this ever renewed impurity of the air we come, we animals
and we plants, and we the human species, with our four billion
discordant opinions, our milleniums of history, our wars and
shames, nobility and pride
OtherCarbonAtomsJointheCycle
Oilivier
burned in a car from
gasoline coming from
a refinery and
extracted from a giant
oil field
Dave
from a limestone rock
dissolved by rain
Coalleen
from a burned coal
brick dug up from an
open-pit coal mine
Storyline by Tyler Volk, CO Rising (2008)
Methaniel
burned when
cooking spaghetti
on a gas stove in
a household and
coming from an
offshore
extraction
platform
Carbon units
—  A gas is measured in fraction of mass or in partial
pressure (the pressure that the gas would have if it
occupied the same volume alone)
—  Atmospheric CO2 is reported in ppm (parts per
million, it’s a unitless fraction)
—  1 Pg = 1 Petagram = 1015 g = 1 Billion metric tons
= 1 Gigaton (Gt)
—  1 Tg = 1 Teragram = 1012 g = 1 Million metric tons
—  1 Kg Carbon (C) = 3.67 Kg Carbon Dioxide (CO2)
Changes in atmospheric CO2 composition
Keeling curve
named after Charles “Dave” Keeling
http://www.esrl.noaa.gov/gmd/ccgg/iadv/
Agrowinghumanfingerprint
The AIRS data show the average concentration (parts per million) over an altitude
range of 3 km to 13 km, whereas the Mauna Loa data show the concentration at
an altitude of 3.4 km and its annual increase at a rate of approximately 2 parts
per million (ppm) per year
TheanthropogenicperturbaCon
—  Over the Anthropocene (~1800 to 1994, Crutzen and
Stoermer, 2000) humankind has released about 340 to
420 Pg C in the form of CO2 (Sabine et al., 2004)
—  Most of it is due to the combustion of fossil fuels (240
Pg) but a significant (and uncertain) fraction also stems
from land use changes (e.g. deforestation)
—  Human activity has accelerated the natural
biogeochemical cycles because this release of carbon is
unprecedented according to the current knowledge
— How can we say unprecedented?
TheT-CO2conundrum
n 
Geological reconstruction of past CO2
n 
Given the observed, positive relationship between
CO2 and temperature, an a priori expectation is that
the CO2-temperature link is of great antiquity (Royer,
2006). This is justified by available observations
though it does not mean that CO2 is always the
dominant forcing
So,where’stheproblem?
CO2wasalothigherinthepast...
—  The records report that natural biogeochemical
cycles controlled the flows of carbon among the
different components, but the involved timescales are
millions of years
—  The term unprecedented refers to timescales of
millennia
—  Natural cycles are still at play (and are expected to
take care of the anthropogenic emissions in the future)
but the impact of this unprecedented perturbation is
likely to be an “undesirable disturbance” for mankind
Climate“…ontherocks”
Vostok
Concordia
How do we know what happened “back then”?
Ice cores are one major source of information on the past
100k years. We can measure the air trapped in bubbles in the
ice.
French-Italian station “Concordia” Progetto Nazionale di
Why“unprecedentedperturbaCon”?
Falkowski et al. (2000)
Howdoweknowthattheincreaseisanthropogenic?
There’s a double signature in the isotopic
composition of atmospheric carbon (isotope:
atom of same atomic number but different
mass)
$ 13C/12 C
n 
n 
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n 
n 
C has 3 isotopes, two stable
forms and one that is
radioactive
isotopic ratios are measured in
terms of relative changes
€
against a standard
fossil-derived CO2 does not
contain any 14C because it all
decayed (Suess Effect).
dilution of atmospheric 14CO2 by
fossil fuel emissions have been
confirmed in tree rings (Tans et
al., 1979)
This is only valid before 1950
δ 13C =
(
&
&
%
)
(
13
12
'
−
C/
C
(
)
sample
standard )
⋅ 1000
12
13
)
C/ C ) standard
(
Allchangesareanthropogenic!
n 
n 
Δ14Cmeasurementshavebeendone
sincethe‘50s.Thelongestrecordisin
Wellington(NZ)
A]erWW2Theatmospherehasbeen
“polluted”bymassivebomb14C
releasethatisalsoexponentially
decaying,besidesthediluCon
n 
25
in addition, fossilderived CO2 contains a
deficit in 13C because
plants prefer lighter
isotopes, therefore δ13C
is also decreasing
Theglobalcarbonbudget
A substantial
portion of the
global carbon
cycle occurs in
the ocean
The ocean is the
largest reservoir
of carbon on
Earth
(~50 times more
carbon than in the
atmosphere)
Pre-industrial and anthropogenic fluxes and reservoirs
(Sarmiento and Gruber, 2002; IPCC-AR4-WG1, 2007)
The available data
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Anthropogenic emissions: trades and usage of
fossil fuels and cement
Atmospheric growth rate: network of observations
(global since 1980)
Estimates
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Land use change (combination of measurements on
deforestation and extrapolations)
Ocean sink (models)
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Land sink (models)
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Estimated sinks (models)
Source: Le Quéré et al 2013; Global Carbon Project 2013
The global carbon budget (1)
Canadell et al., 2007
The global carbon budget (2)
Canadell et al., 2007
The global carbon budget
Ocean uptake
(model
estimate)
Land uptake
(derived by
difference)
Atmospheric
growth rate
(observations)
Canadell et al., 2007
FateofAnthropogenicCO2Emissions(2000-2009)
1.1±0.7 PgC y-1
4.1±0.1 PgC y-1
47%
7.7±0.5 PgC y-1
+
2.4 PgC y-1
27%
Calculated as the residual of
all other flux components
26%
2.3±0.4 PgC y-1
Average of 5 models
Global Carbon Project 2010; Updated from Le Quéré et al. 2009, Nature Geoscience; Canadell et al. 2007, PNAS
The atmospheric viewpoint
Updates on the carbon budget
http://www.globalcarbonproject.org
Where has the carbon gone?
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Aim: quantify the redistribution of
anthropogenic carbon added to the natural
global carbon system
About 50% of the emissions is captured by
natural sinks
Expected redistribution between atmosphere
and ocean should be ~ 1:50
Only 1/4 is apparently gone in the ocean
Why is the oceanic uptake so small?
Anthropogenic Perturbation of the Global Carbon Cycle
Perturbation of the global carbon cycle caused by anthropogenic activities, averaged globally for
the decade 2004–2013 (GtC/yr)
Source: Le Quéré et al 2013; CDIAC Data; NOAA/ESRL Data; Global Carbon Project 2013
Ocean Sink estimates
Ocean carbon sink continues to increase
this carbon budget
individual ocean models
data products
Source: Le Quéré et al 2014; Global Carbon Project 2014
Individual estimates from Buitenhuis et al. (2010); Aumont and Bopp (2006); Doney et al. (2009); Assmann et al. (2010); Ilyiana et al. (2013); Sérérian et al. (2013); Oke et al. (2013);
Landschützer et al. (2014); Park et al. (2010); Rödenbeck et al. (2014). References provided in Le Quéré et al. (2014).
What regulates ocean CO2
exchanges with the atmosphere?
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Short-medium term (~ 100 years) exchanges
dependent on the disequilibrium between atmosphere
and ocean concentrations
- 
- 
- 
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Carbonate chemistry
Biological activity
Ocean mixing and deep water formation (slowest
“quick” component)
Long term (> 1000 years) regulation due to
geochemical reactions with other Earth System
components
- 
- 
Ocean floor sediments
Crustal rocks
The role of the
Southern Ocean
Takahashi et al. (2012)
About ½ of the ocean
sink occurs in the
sub-Antarctic zone
EarthSystemScience
—  ESSdislikesthedivisionofEarthintosectorial
disciplinesstudyingtheatmosphere,hydrosphere,
criosphereandthebiosphere.Thepresenceoflifeon
EarthhasdeterminedthechemicalcomposiConofthe
environmentwherelife“lives”today.
—  ESSconsiderstheEarthasasingledynamicen-tywith
Cghtlinkagesbetweenthephysicalenvironment,
materialsandlivingcomponents
—  AcharacterisCcofESSisthatscienCstsareunableto
performcontrolledexperimentsontheplanetasa
wholeandthenobservetheresults.
Laboratoryexperiments?
• There is no spare Earth to experiment with. ESS is similar to
astrophysics: one cannot experiment with galaxies
• This is an important consideration, because it is precisely such
whole-Earth, system-scale experiments, incorporating the full
complexity of interacting processes and feedbacks, that might
ideally be required to fully verify or falsify climate change
hypotheses (Schellnhuber et al., 2004, in Chap. 1, IPCC WG1,
2007).
• Nevertheless, countless empirical tests of numerous different
hypotheses have built up a massive body of Earth system
science knowledge, testing aspects of the Earth system and
combining observations with models
• The experiments with the Earth System are usually simulationbased, using numerical climate models that have nowadays
evolved into Earth System Models (ESMs)
What is an ESM?
(credits: M. Hague)
EarthSystemModel
Oceanbiogeochemicalprocesses
Landbiogeochemicalprocesses
The physical interface includes
biogeochemical variables
EarthSystemexperiments
—  Climate Models are generally used for
—  a:ribu-onstudies:understandingthecausality
betweenobservedchangesandthemajor
naturalandanthropogenicforcings
—  scenariostudies:makingfutureprojecConson
thestateoftheclimateaccordingtopredefined
scenariosofanthropogenicusageoftheEarth
resources
Futurescenarios:wheredotheycome
from?
—  A SCENARIO is a
plausible description of
how the future may
develop, based on a
coherent and internally
consistent set of
assumptions about key
relationships and driving
forces (e.g., population,
rate of technology
change, prices).
Note that scenarios are
neither predictions nor
forecasts. (OECD, Organisation for
Economic Co-operation and Development )
http://www.ipcc.ch/ipccreports/sres
ProjecCons
—  Climate scientists rarely use the term prediction
when referring to future climate conditions.
—  This stems from the fact that a future climate
simulation is not exactly an “initial value problem”
but mostly a “boundary value problem”
—  The correct term is “projection”, because the
models are used to project into the future the
climate conditions driven by a set of predefined,
time-evolving forcing scenarios.
Emissionscenarios
IPCC Special Report on Emission Scenarios, 2001
http://www.grida.no/climate/ipcc/emission/index.htm
RepresentaCveConcentraConPathways
(RCP)
RCPareclassifiedintermsofradiaCve
forcing
Global
projecCons
Observations since
1950 compared with
projections from the
previous IPCC
assessments.
Observed globally and
annually averaged CO2
concentrations in parts
per million (in ppm)
Estimated changes in the
observed globally and
annually averaged surface
temperature anomaly
relative to 1961–1990 (in
°C)
Estimated changes in the
observed global annual
mean sea level (in cm)
Theuncertaintycascade
Emission
scenarios
Carbon cycle
response
Adapted from IPCC 2001
Global climate Regional climate Range of possible
sensitivity
change scenarios impacts
BacktoOurcarbonatom
[…] is again among us, in a glass
of milk. […] It is swallowed; and
[…] the chain is meticulously
broken apart and the fragments,
one by one, are accepted or
rejected. One, the one that
concerns us, crosses the intestinal
threshold and enters the
bloodstream: it migrates, knocks at
the door of a nerve cell, enters, and
supplants the carbon which was
part of it. This cell belongs to a
brain, and it is Primo’s brain, the
brain of the person who is writing;
and the cell in question, and
within it the atom in question, is in
charge of his writing, in a gigantic
minuscule game which nobody
has yet described. It […] guides
that hand of him to impress on our
screen this dot, here,
.
this one