The Case of the Missing Carbon
By Tim Appenzeller
National Geographic Magazine
Hooked on fossil fuels, humans pump carbon dioxide into the atmosphere.
Fortunately, plants and ocean waters gather it in. But what happens when the
planet's great carbon recycling system goes awry?
The coal, oil, and natural gas that drive the industrial world's economy all
contain carbon inhaled by plants hundreds of millions of years ago—carbon that
now is returning to the atmosphere through smokestacks and exhaust pipes,
joining emissions from forest burned to clear land in poorer countries. Carbon
dioxide is foremost in an array of gases from human activity that increase the
atmosphere's ability to trap heat. (Methane from cattle, rice fields, and landfills,
and the chlorofluorocarbons in some refrigerators and air conditioners are
others.) Few scientists doubt that this greenhouse warming of the atmosphere is
already taking hold. Melting glaciers, earlier springs, and a steady rise in global
average temperature are just some of its harbingers.
By rights it should be worse. Each year humanity dumps roughly 8 billion
metric tons of carbon into the atmosphere, 6.5 billion tons from fossil fuels and 1.5
billion from deforestation. But less than half that total, 3.2 billion tons, remains in
the atmosphere to warm the planet. Where is the missing carbon? "It's a really
major mystery, if you think about it," says Wofsy, an atmospheric scientist at
Harvard University. His research site in the Harvard Forest is apparently not the
only place where nature is breathing deep and helping save us from ourselves.
Forests, grasslands, and the waters of the oceans must be acting as carbon sinks.
They steal back roughly half of the carbon dioxide we emit, slowing its buildup in
the atmosphere and delaying the effects on climate.
Who can complain? No one, for now. But the problem is that scientists can't
be sure that this blessing will last, or whether, as the globe continues to warm, it
might even change to a curse if forests and other ecosystems change from carbon
sinks to sources, releasing more carbon into the atmosphere than they absorb. The
doubts have sent researchers into forests and rangelands, out to the tundra and to
sea, to track down and understand the missing carbon.
Word
case
missing
Definition
a question or problem that will be dealt with
something that is missing is not in its usual place, so that you cannot
find it
a chemical substance that exists in a pure form as diamonds,
carbon
graphite etc, or in an impure form as coal, petrol etc. It is a chemical
element: symbol C
if you are hooked on a drug, you feel a strong need for it and you
hooked on
cannot stop taking it
a fuel such as coal or oil that is produced by the very gradual
fossil fuel
decaying of animals or plants over millions of years
to make liquid or gas move in a particular direction
pump
the gas produced when animals breathe out, when carbon is burned
carbon
in air, or when animal or vegetable substances decay
dioxide
to get things from different places and put them together in one place
gather
the process of treating used objects or materials so that they can be
recycling
used again
if something goes awry, it does not happen in the way that was
go awry
planned
to make a person or animal work hard
drive
if a substance contains something, that thing is part of it
contain
to breathe in air, smoke, or gas
inhale
smokestack a tall chimney at a factory or on a ship
exhaust pipe a pipe on a car or machine that waste gases pass through
a gas or other substance that is sent into the air
emission
in a leading position among a group of people or things
foremost
a group of people or things, especially one that is large or impressive
array
to prevent something such as gas or water from getting away
trap
a gas that you cannot see or smell, which can be burned to give heat
methane
a place where waste is buried under the ground
landfill
chlorofluoro- CFC - a gas used in fridges and aerosol cans, believed to be
responsible for damaging the ozone layer
carbon
refrigerator a large piece of electrical kitchen equipment, shaped like a cupboard,
used for keeping food and drink cool
a machine that makes the air in a room or building cooler and drier
air
conditioner
to think that something may not be true or that it is unlikely
doubt
greenhouse the gradual warming of the air surrounding the Earth as a result of
heat being trapped by pollution
warming
to start to have a definite effect
take hold
Word
melt
glacier
steady
Definition
if something solid melts or if heat melts it, it becomes liquid
a large mass of ice which moves slowly down a mountain valley
continuing or developing gradually or without stopping, and not
likely to change
an increase in number, amount, or value
rise
the average amount is the amount you get when you add together
average
several quantities and divide this by the total number of quantities
a sign that something is going to happen soon
harbinger
used to describe what should happen if things are done fairly or
by rights
correctly
people in general
humanity
to get rid of something that you do not want
dump
not exactly
roughly
a unit for measuring weight, equal to 1000 kilograms
metric ton
deforestation the cutting or burning down of all the trees in an area
very important
major
an event, situation etc that people do not understand or cannot
mystery
explain because they do not know enough about it
research site the place where serious study of a subject is done, in order to
discover new facts or test new ideas
apparently used to say that you have heard that something is true, although you
are not completely sure about it
a large area of land covered with wild grass
grassland
a container
sink
to take something that belongs to someone else
steal
to send out gas, heat, light, sound etc
emit
an increase over a period of time
build-up
to make someone or something late
delay
the way in which an event, action, or person changes someone or
effect
something
something that you have or something that happens which is good
blessing
because it improves your life, helps you in some way, or makes you
happy
something that causes trouble, harm etc
curse
a thing, place, activity etc that you get something from
source
to let a substance flow out
release
to take in liquid, gas, or another substance from the surface or space
absorb
around something
a large area of land covered with grass, on which cattle are kept
rangeland
Word
tundra
track down
Definition
the large flat areas of land in the north of Russia, Canada etc, where
it is very cold and there are no trees
to find someone or something that is difficult to find by searching or
looking for information in several different places