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from: http://www.unfccc.int/resource/beginner.html
Beginners Guide
to the Convention
Understanding
Climate Change:
A Beginner's Guide to the UN Framework Convention
Introduction:
A giant asteroid could hit the earth! Something else could happen! The
global temperature could rise! Wake up!
The 1990s have been
a time of international soul- searching about the environment. What are
we doing to our planet? More and more, we are realising that the Industrial
Revolution has changed forever the relationship between humanity and nature.
There is real concern that by the middle or the end of the next century
human activities will have changed the basic conditions that have allowed
life to thrive on earth.
The 1992 United
Nations Framework Convention on Climate Change is one of a series
of recent agreements through which countries around the world are banding
together to meet this challenge. Other treaties deal with such matters
as pollution of the oceans, expanding deserts, damage to the ozone layer,
and the rapid extinction of plant and animal species. The Climate Change
Convention focuses on something particularly disturbing: we are changing
the way energy from the sun interacts with and escapes from our planet's
atmosphere. By doing that, we risk altering the global climate. Among
the expected consequences are an increase in the average temperature of
the earth's surface and shifts in world-wide weather patterns. Other --
unforeseen -- effects cannot be ruled out.
We have a few problems
to face up to.
Problem No. 1 (the big problem):
Scientists see a real risk that the climate will change rapidly and dramatically
over the coming decades and centuries. Can we handle it?
A giant
asteroid did hit the earth -- about 65 million years ago. Splat. Scientists
speculate that the collision threw so much dust into the atmosphere
that the world was dark for three years. Sunlight was greatly reduced,
so many plants could not grow, temperatures fell, the food chain collapsed,
and many species, including the largest ever to walk the earth, died
off.
That, at least, is
the prevailing theory of why the dinosaurs became extinct. Even those
who weren't actually hit by the asteroid paid the ultimate price.
The catastrophe that
befell the dinosaurs is only one illustration, if dramatic, of how changes
in climate can make or break a species.
According to another
theory, human beings evolved when a drying trend some 10 million years
ago was followed around three million years ago by a sharp drop in world
temperature. The ape-like higher primates in the Great Rift Valley of
Africa were used to sheltering in trees, but, under this long-term climate
shift, the trees were replaced with grassland. The 'apes' found themselves
on an empty plain much colder and drier than what they were used to, and
extremely vulnerable to predators.
Extinction was a real
possibility, and the primates appear to have responded with two evolutionary
jumps -- first to creatures who could walk upright over long distances,
with hands free for carrying children and food; and then to creatures
with much larger brains, who used tools and were omnivorous (could eat
both plants and meat). This second, large-brained creature is generally
considered to be the first human.
Shifts in climate
have shaped human destiny ever since, and people have largely responded
by adapting, migrating, and growing smarter. During a later series of
ice ages, sea levels dropped and humans moved across land bridges from
Asia to the Americas and the Pacific islands. Many subsequent migrations,
many innovations, many catastrophes have followed. Some can be traced
to smaller climatic fluctuations, such as a few decades or centuries of
slightly higher or lower temperatures, or extended droughts. Best known
is the Little Ice Age that struck Europe in the early Middle Ages, bringing
famines, uprisings, and the withdrawal of northern colonies in Iceland
and Greenland. People have suffered under the whims of climate for millennia,
responding with their wits, unable to influence these large events.
Until now. Ironically,
we humans have been so remarkably successful as a species that we may
have backed ourselves into a corner. Our numbers have grown to the point
where we have less room for large-scale migration should a major climate
shift call for it. And the products of our large brains -- our industries,
transport, and other activities -- have led to something unheard of in
the past. Previously the global climate changed human beings. Now human
beings seem to be changing the global climate. The results are uncertain,
but if current predictions prove correct, the climatic changes over the
coming century will be larger than any since the dawn of human civilisation.
The principal change
to date is in the earth's atmosphere. The giant asteroid that felled the
dinosaurs threw large clouds of dust into the air, but we are causing
something just as profound if more subtle. We have changed, and are continuing
to change, the balance of gases that form the atmosphere. This is especially
true of such key "greenhouse gases" as carbon dioxide (CO2),
methane (CH4), and nitrous oxide (N2O). (Water vapour is the most important
greenhouse gas, but human activities do not affect it directly.) These
naturally occurring gases make up less than one tenth of one per cent
of the total atmosphere, which consists mostly of oxygen (21 per cent)
and nitrogen (78 per cent). But greenhouse gases are vital because they
act like a blanket around the earth. Without this natural blanket the
earth's surface would be some 30 C colder than it is today.
The problem is that
human activity is making the blanket "thicker". For example,
when we burn coal, oil, and natural gas we spew huge amounts of carbon
dioxide into the air. When we destroy forests the carbon stored in the
trees escapes to the atmosphere. Other basic activities, such as raising
cattle and planting rice, emit methane, nitrous oxide, and other greenhouse
gases. If emissions continue to grow at current rates, it is almost certain
that atmospheric levels of carbon dioxide will double from pre-industrial
levels during the 21st century. If no steps are taken to slow greenhouse
gas emissions, it is quite possible that levels will triple by the year
2100.
The most direct result,
says the scientific consensus, is likely to be a "global warming"
of 1.5 to 4.5 C over the next 100 years. That is in addition to an apparent
temperature increase of half a degree Centigrade since the pre-industrial
period before 1850, at least some of which may be due to past greenhouse
gas emissions.
Just how this would
affect us is hard to predict because the global climate is a very complicated
system. If one key aspect -- such as the average global temperature --
is altered, the ramifications ripple outward. Uncertain effects pile onto
uncertain effects. For example, wind and rainfall patterns that have prevailed
for hundreds or thousands of years, and on which millions of people depend,
may change. Sea-levels may rise and threaten islands and low-lying coastal
areas. In a world that is increasingly crowded and under stress -- a world
that has enough problems already -- these extra pressures could lead directly
to more famines and other catastrophes.
While scientists are
scrambling to understand more clearly the effects of our greenhouse gas
emissions, countries around the globe recently joined together to confront
the problem.
How the Convention
responds
-- It recognises
that there is a problem. That's a significant step. It is not easy
for the nations of the world to agree on a common course of action, especially
one that tackles a problem whose consequences are uncertain and which
will be more important for our grandchildren than for the present generation.
Still, the Convention was negotiated and signed by 165 states in a little
over two years, and over 100 have already ratified and so are legally
bound by it. The treaty took effect on 21 March 1994.
-- It sets an "ultimate
objective" of stabilising "greenhouse gas concentrations in
the atmosphere at a level that would prevent dangerous anthropogenic (human-induced)
interference with the climate system." The objective does not
specify what these concentrations should be, only that they be at a level
that is not dangerous. This acknowledges that there is currently no scientific
certainty about what a dangerous level would be. Scientists believe it
will take about another decade (and the next generation of supercomputers)
before today's uncertainties (or many of them) are significantly reduced.
The Convention's objective thus remains meaningful no matter how the science
evolves.
-- It directs that
"such a level should be achieved within a time-frame sufficient to
allow ecosystems to adapt naturally to climate change, to ensure that
food production is not threatened and to enable economic development to
proceed in a sustainable manner." This highlights the main concerns
about food production -- probably the most climate-sensitive human activity
-- and economic development. It also suggests (as most climatologists
believe) that some change is inevitable and that adaptive as well as preventive
measures are called for.
Again, this leaves
room for interpretation in the light of scientific findings and the trade-offs
and risks that the global community is willing to accept.
Problem No. 2: If the consequences
of a problem are uncertain, do you ignore the problem or do you do something
about it anyway.
Climate change is
a threat to mankind. But no one is certain about its future effects or
their severity. Responding to the threat is expected to be expensive,
complicated, and difficult. There is even some disagreement over whether
any problem exists at all: while many people worry that the effects will
be extremely serious, others argue that scientists cannot prove that what
they suspect will happen will actually happen. In addition, it is not
clear who (in the various regions of the world) will suffer most. Yet
if the nations of the world wait until the consequences and victims are
clear, it will probably be too late to act. What should we do?
The truth is that
in most scientific circles the issue is no longer whether or not climate
change is a potentially serious problem. Rather, it is how the problem
will develop, what its effects will be, and how these effects can best
be detected. Computer models of something as complicated as the planet's
climate system are not far enough advanced yet to give clear and unambiguous
answers. Nevertheless, while the when, where, and how remain uncertain,
the big picture painted by these climate models cries out for attention.
For example:
-- Regional rain
patterns may change. At the global level, the evapo-transpiration
cycle is expected to speed up. This means that it would rain more, but
the rain would evaporate faster, leaving soils drier during critical parts
of the growing season. New or worsening droughts, especially in poorer
countries, could reduce supplies of clean, fresh water to the point where
there are major threats to public health. Because they still lack confidence
in regional scenarios, scientists are uncertain about which areas of the
world risk becoming wetter and which drier. But with global water resources
already under severe strain from rapid population growth and expanding
economic activity, the danger is clear.
-- Climate and
agricultural zones may shift towards the poles. In the mid-latitude
regions the shift is expected to be 200 to 300 kilometres for every degree
Celsius of warming. Increased summer dryness may reduce mid- latitude
crop yields by 10 to 30 per cent, and it is possible that today's leading
grain-producing areas (such as the Great Plains of the United States)
would experience more frequent droughts and heat waves. The poleward edges
of the mid-latitude agricultural zones -- northern Canada, Scandinavia,
Russia, and Japan in the northern hemisphere, and southern Chile and Argentina
in the southern hemisphere -- might benefit from higher temperatures.
However, in some areas rugged terrain and poor soil would prevent these
countries from compensating for reduced yields in today's more productive
areas. -
- Melting glaciers
and the thermal expansion of sea water may raise sea levels, threatening
low-lying coastal areas and small islands.
The global mean sea
level has already risen by around 15 centimetres during the past century,
and global warming is expected to cause a further rise of about 18 cm
by the year 2030. If the current trend in greenhouse gas emissions continues,
the rise could amount to 65 cm above current levels by the year 2100.
The most vulnerable land would be the unprotected, densely populated coastal
regions of some of the world's poorest countries. Bangladesh, whose coast
is already prone to devastating floods, would be a likely victim, as would
many small island states such as the Maldives.
These scenarios are
alarming enough to raise concern, but too uncertain to enable governments
to make many specific decisions about what to do. The picture is fuzzy.
Some governments, beleaguered by other problems and responsibilities and
bills to pay, understandably are tempted to do nothing at all. Maybe the
threat will go away. Or someone else will deal with it. Maybe another
giant asteroid will hit the earth. Who knows?
How the Convention
responds
-- It establishes
a framework and a process for agreeing to specific actions -- later.
The diplomats who wrote the Framework Convention on Climate Change saw
it as a launching pad for potential further action in the future. They
recognised that it would not be possible in the year 1992 for the world's
governments to agree on a detailed blueprint for tackling climate change.
But by establishing a framework of general principles and institutions,
and by setting up a process through which governments can meet regularly,
they got things started.
A key benefit of this
approach is that it allows countries to begin discussing an issue even
before they all fully agree that it is, in fact, a problem. Even sceptical
countries feel it is worthwhile participating. (Or, to put it another
way, they'd feel uneasy about being left out.) This creates legitimacy
for the issue, and a sort of international peer pressure to take the subject
seriously.
The Convention is
designed to allow countries to weaken or strengthen the treaty in response
to new scientific developments. For example, they can agree to take more
specific actions (such as reducing emissions of greenhouse gases by a
certain amount) by adopting "amendments" or "protocols"
to the Convention.
The treaty promotes
action in spite of uncertainty on the basis of a recent development in
international law and diplomacy called the "precautionary principle."
Under traditional international law, an activity generally has not been
restricted or prohibited unless a direct causal link between the activity
and a particular damage can be shown. But many environmental problems,
such as damage to the ozone layer and pollution of the oceans, cannot
be confronted if final proof of cause and effect is required. In response,
the international community has gradually come to accept the precautionary
principle, under which activities that threaten serious or irreversible
damage can be restricted or even prohibited before there is absolute scientific
certainty about their effects.
-- The Convention
takes preliminary steps that clearly make sense for the time being.
Countries ratifying the Convention -- called "Parties to the Convention"
in diplomatic jargon -- agree to take climate change into account in such
matters as agriculture, energy, natural resources, and activities involving
sea-coasts. They agree to develop national programmes to slow climate
change. The Convention encourages them to share technology and to cooperate
in other ways to reduce greenhouse gas emissions, especially from energy,
transport, industry, agriculture, forestry, and waste management, which
together produce nearly all greenhouse gas emissions attributable to human
activity.
-- The Convention
encourages scientific research on climate change. It calls for data
gathering, research, and climate observation, and it creates a "subsidiary
body" for "scientific and technological advice" to help
governments decide what to do next. Each country that is a Party to the
Convention must also develop a greenhouse gas "inventory" listing
its national sources (such as factories and transport) and "sinks"
(forests and other natural ecosystems that absorb greenhouse gases from
the atmosphere). These inventories will have to be updated regularly and
made public. The information they provide on which activities emit how
much of each gas will be essential for monitoring changes in emissions
and determining the effects of measures taken to control emissions.
Problem No. 3: It's not
fair.
If a giant asteroid
hits the earth, that's nobody's fault. The same cannot be said for global
warming.
There is a fundamental
unfairness to the climate change problem that chafes at the already uneasy
relations between the rich and poor nations of the world. Countries with
high standards of living are mostly (if unwittingly) responsible for the
rise in greenhouse gases. These early industrialisers -- Europe, North
America, Japan, and a few others -- created their wealth in part by pumping
into the atmosphere vast amounts of greenhouse gases long before the likely
consequences were understood. Developing countries now fear being told
that they should curtail their own fledgling industrial activities --
that the atmosphere's safety margin is all used up.
Because energy-related
emissions are the leading cause of climate change, there will be growing
pressure on all countries to reduce the amounts of coal and oil they use.
There also will be pressure (and incentives) to adopt advanced technologies
so that less damage is inflicted in the future. Buying such technologies
can be costly.
Countries in the early
stages of industrialisation -- countries struggling hard to give their
citizens better lives -- don't want these additional burdens. Economic
development is difficult enough already. If they agreed to cut back on
burning the fossil fuels that are the cheapest, most convenient, and most
useful for industry, how could they make any progress?
There are other injustices
to the climate change problem. The countries to suffer the most if the
predicted consequences come about -- if agricultural zones shift or sea
levels rise or rainfall patterns change -- will probably be in the developing
world. These nations simply do not have the scientific or economic resources,
or the social safety nets, to cope with disruptions in climate. Also,
in many of these countries rapid population growth has pushed many millions
of people onto marginal land -- the sort of land that can change most
drastically due to variations in climate.
How the Convention
responds
-- It puts the
lion's share of the responsibility for battling climate change -- and
the lion's share of the bill -- on the rich countries. The Convention
notes that the largest share of historical and current emissions originates
in developed countries. Its first basic principle is that these countries
should take the lead in combating climate change and its adverse impacts.
Specific commitments in the treaty relating to financial and technological
transfers apply only to the 24 developed countries belonging to the Organisation
for Economic Cooperation and Development (OECD -- excepting Mexico, which
joined the OECD in 1994). They agree to support climate change activities
in developing countries by providing financial support above and beyond
any financial assistance they already provide to these countries.
Specific commitments
concerning efforts to limit greenhouse gas emissions and enhance natural
sinks apply to the OECD countries as well as to 12 "economies in
transition" (Central and Eastern Europe and the former Soviet Union).
Although negotiations left the treaty language less than clear, it is
generally accepted that the OECD and transition countries should at a
minimum seek to return by the year 2000 to the greenhouse gas emission
levels they had in 1990.
-- The Convention
recognises that poorer nations have a right to economic development.
It notes that the share of global emissions of greenhouse gases originating
in developing countries will grow as these countries expand their industries
to improve social and economic conditions for their citizens.
-- It acknowledges
the vulnerability of poorer countries to the effects of climate change.
One of the Convention's basic principles is that the specific needs and
circumstances of developing countries should be given "full consideration"
in any actions taken. This applies in particular to those whose fragile
ecosystems are highly vulnerable to the impacts of climate change. The
Convention also recognises that states which depend on income from coal
and oil would face difficulties if energy demand changes.
Problem No. 4: If the whole
world starts consuming more and living the good life, can the planet stand
the strain?
As
the human population continues to grow, the demands human beings place
on the environment increase. The demands are becoming all the greater
because these rapidly increasing numbers of people also want to live
better lives. More and better food, more and cleaner water, more electricity,
refrigerators, automobiles, houses and apartments, land on which to
put houses and apartments . . .
Already there are
severe problems supplying enough fresh water to the world's billions.
Burgeoning populations are draining the water from rivers and lakes, and
vast underground aquifers are steadily being depleted. What will people
do when these natural "tanks" are empty? There are also problems
growing and distributing enough food -- widespread hunger in many parts
of the world attests to that. There are other danger signals. The global
fish harvest has declined sharply; as large as the oceans are, the most
valuable species have been effectively fished out.
Global warming is
a particularly ominous example of humanity's insatiable appetite for natural
resources. During the last century we have dug up and burned massive stores
of coal, oil, and natural gas that took millions of years to accumulate.
Our ability to burn up fossil fuels at a rate that is much, much faster
than the rate at which they were created has upset the natural balance
of the carbon cycle. The threat of climate change arises because one of
the only ways the atmosphere -- also a natural resource -- can respond
to the vast quantities of carbon being liberated from beneath the earth's
surface is to warm up.
Meanwhile, human expectations
are not tapering off. They are increasing. The countries of the industrialised
"North" have 20 per cent of the world's people but use about
80 per cent of the world's resources. By global standards, they live extremely
well. It's nice living the good life, but if everyone consumed as much
as the North Americans and Western Europeans consume -- and billions of
people aspire to do just that -- there probably would not be enough clean
water and other vital natural resources to go around. How will we meet
these growing expectations when the world is already under so much stress?
How the Convention
responds
-- It supports
the concept of "sustainable development." Somehow, mankind
must learn how to alleviate poverty for huge and growing numbers of people
without destroying the natural environment on which all human life depends.
Somehow a way has to be found to develop economically in a fashion that
is sustainable over a long period of time. The buzzword for this challenge
among environmentalists and international bureaucrats is "sustainable
development". The trick will be to find methods for living well while
using critical natural resources at a rate no faster than that at which
they are replaced. Unfortunately, the international community is a lot
farther along in defining the problems posed by sustainable development
than it is in figuring out how to solve them.
-- The Convention
calls for developing and sharing environmentally sound technologies and
know-how. Technology will clearly play a major role in dealing with
climate change. If we can find practical ways to use cleaner sources of
energy, such as solar power, we can reduce the consumption of coal and
oil. Technology can make industrial processes more efficient, water purification
more viable, and agriculture more productive for the same amount of resources
invested. Such technology must be made widely available -- it must somehow
be shared by richer and more scientifically advanced countries with poorer
countries that have great need of it.
-- The Convention
emphasises the need to educate people about climate change. Today's
children and future generations must learn to look at the world in a different
way than it has been looked at by most people during the 20th century.
This is both an old and a new idea. Many (but not all!) pre-industrial
cultures lived in balance with nature. Now scientific research is telling
us to do much the same thing. Economic development is no longer a case
of "bigger is better" -- bigger cars, bigger houses, bigger
harvests of fish, bigger doses of oil and coal. We must no longer think
of human progress as a matter of imposing ourselves on the natural environment.
The world -- the climate and all living things -- is a closed system;
what we do has consequences that eventually come back to affect us. Tomorrow's
children -- and today's adults, for that matter -- will have to learn
to think about the effects of their actions on the climate. When they
make decisions as members of governments and businesses, and as they go
about their private lives, they will have to take the climate into account.
In other words, human
behaviour will have to change -- probably the sooner the better. But such
things are difficult to prescribe and predict. There is, for example,
the matter of what sacrifices might have to be made by everyone for the
good of the global climate. That leads to...
Problem No. 5: Who has the
energy, time, or money left to deal with climate change, when we have
so many other problems?
A valid
point.
How the Convention
responds
-- It starts slowly.
It doesn't make too many demands (or requests) for the time being. But
stay tuned. The Framework Convention on Climate Change is a general
treaty with just a few specific requirements. More and bigger requirements
may come later, in the form of amendments and protocols. This will happen
as scientific understanding of climate change becomes clearer and as the
countries of the world, already suffering from a case of "disaster
fatigue", adjust to the idea that they have yet another crisis to
face and pay for. War, famine, AIDS, the ozone "hole", acid
rain, the loss of ecosystems and species ... Thinking about these problems,
people could be forgiven for wondering if they should throw in the towel.
We can't give up,
of course. And while the Convention cannot claim to have the issue all
sorted out, it does make a start. Things are beginning to happen. Developed
countries are making national plans with the aim of returning their greenhouse
gas emissions to 1990 levels by the year 2000 -- thereby reversing the
historical trend of ever-increasing emissions. Countries that have ratified
the treaty are beginning to gather data on their emissions and on the
present climate. More and more, people and governments are talking and
thinking about climate change.
What happens next?
Step by step, national governments committed to controlling their emissions
must begin tightening emissions standards and requiring more replanting
of trees; some countries are already working on such standards. Local
and urban governments -- which often have direct responsibility for transport,
housing, waste management, and other greenhouse gas-emitting sectors of
the economy -- have a role, too. They can start designing and building
better public transport systems, for example, and creating incentives
for people to use them rather than private automobiles. They should tighten
construction codes so that new houses and office buildings can be heated
or cooled with less fuel. Meanwhile, industrial companies need to start
shifting to new technologies that use fossil fuels and raw materials more
efficiently. Wherever possible they should switch to renewable energy
sources such as wind and solar power. They should also redesign products
such as refrigerators, automobiles, cement mixes, and fertilisers so that
they produce lower greenhouse gas emissions. Farmers should look to technologies
and methods that reduce the methane emitted by livestock and rice fields.
Individual citizens, too, must cut their use of fossil fuels -- take public
transport more often, switch off the lights in empty rooms -- and be less
wasteful of all natural resources.
It may seem naive
to expect behavioural changes of this magnitude. But the potential for
more responsible behaviour on behalf of the climate is nevertheless there.
It is possible that as time passes and more is known about the threats
posed by climate change, such responses will seem a lot less naive and
a lot more vital to humanity's well-being.
-- The Convention
is based on sharing the burdens of coping with climate change. This
is important. The atmosphere is a shared resource, part of the "global
commons". The treaty tries to make sure that any sacrifices made
in protecting this resource will be shared fairly among countries -- in
accordance with their "common but differentiated responsibilities
and respective capabilities and their social and economic conditions".
This means, the participating countries hope, that whatever ultimately
has to be done will be done by enough participants to make the benefits
worth the sacrifices. It is easier to sacrifice towards the common good
when you are sure everyone else is pitching in.
Conclusion: Into
the 21st century and beyond Climate change would have lasting
consequences. One giant asteroid came along 65 million years ago, and
that was it for the dinosaurs.
In facing up to man-made
climate change, human beings are going to have to think in terms of decades
and centuries. The job is just beginning. Many of the effects of climate
shifts will not be apparent for two or three generations. In the future,
everyone may be hearing about -- and living with -- this problem.
The Framework Convention
takes this into account. It is aimed at the next century as much as at
this one. It establishes institutions to support efforts to carry out
long-term commitments and to monitor long-term efforts to minimise --
and adjust to -- climate change. The Conference of the Parties, in which
all states that have ratified the treaty are represented, is the Convention's
supreme body. It meets for the first time in March 1995 and on a yearly
basis thereafter. It will promote and review the implementation of the
Convention and, if appropriate, strengthen it. The Conference of Parties
will be assisted by two subsidiary bodies, one for scientific and technological
advice and the other for implementation. The Conference of Parties may
also make additional arrangements in the future to help support the needs
of the Convention.
The treaty also reflects
a reasonable view about how the world will function politically in the
future, and assumptions about how problems can best be solved over the
next century. It is based on a cooperative rather than a confrontational
approach -- it assumes that countries can successfully tackle problems
such as climate change only if they work together as a team. And it is
designed to work well in a multi-polar world in which many countries have
influence and the power to apply peer pressure to persuade others to uphold
their obligations.
How can we strike
a balance with the environmental conditions that allow us to exist in
the first place? That is a question humankind has largely ignored up to
now, at its peril. From here on it is a challenge we probably will have
to face as long as our species exists.
What is the greenhouse effect?
In the long term,
the earth must shed energy into space at the same rate at which it absorbs
energy from the sun. Solar energy arrives in the form of short-wavelength
radiation. Some of this radiation is reflected away by the earth's surface
and atmosphere. Most of it, however, passes straight through the atmosphere
to warm the earth's surface. The earth gets rid of this energy (sends
it back out into space) in the form of long- wavelength, infra-red radiation.
Most of the infra-red
radiation emitted upwards by the earth's surface is absorbed in the atmosphere
by water vapour, carbon dioxide, and the other naturally occurring "greenhouse
gases". These gases prevent energy from passing directly from the
surface out into space. Instead, many interacting processes (including
radiation, air currents, evaporation, cloud-formation, and rainfall) transport
the energy high into the atmosphere. From there it can radiate into space.
This slower, more indirect process is fortunate for us, because if the
surface of the earth could radiate energy into space unhindered, the earth
would be a cold, lifeless place -- a bleak and barren planet rather like
Mars.
By increasing the
atmosphere's ability to absorb infra-red energy, our greenhouse gas emissions
are disturbing the way the climate maintains this balance between incoming
and outgoing energy. A doubling of the concentration of long-lived greenhouse
gases (which is projected to occur early in the next century) would, if
nothing else changed, reduce the rate at which the planet can shed energy
into space by about 2 per cent. Energy cannot simply accumulate. The climate
somehow will have to adjust to get rid of the extra energy -- and while
2 per cent may not sound like much, over the entire earth that amounts
to trapping the energy content of some 3 million tons of oil every minute.
Scientists point out
that we are altering the energy "engine" that drives the climate
system. Something has to change to absorb the shock.
Published by the UNEP/WMO
Information Unit on Climate Change. Printed in December 1994. Permission
is granted to reproduce the contents giving appropriate credit. For more
information, contact UNEP/IUC, Geneva Executive Center, Box 356, 1219
Châtelaine, Switzerland
©
UNFCCC
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