4. .

5. Earth energy for the greenhouse effect, life on
Earth would not exist. The Sun emits radiation
to the Earth. If we could imagine a flat surface
at the top of the atmosphere, that radiation is
about 340 watts per square meter (340 W/m-
2). Earth’s surface, leaving some 240 W/m-2
that heats up the surface of the Earth.
Incoming solar radiation: + 340 W Outgoing radiation: - 420 W m-2
m-2 Greenhouse effect: + 180 W m-2
Reflected from clouds, the Earth’s Net outgoing (thermal) radiation
surface, etc.: - 100 W m-2

6. The greenhouse effect is a good thing life on Earth. The
problem arises Because humankind is Adding to the
effect by increasing the amounts of CO2 and a f in the
atmosphere, notably methane (CH4) and nitrous oxide
(N2O).

7. The next issue is to predict what would happen if these
temperature changes were allowed to happen. The science of
climate change impact assessment is very uncertain, not least
because humans have the capacity to adapt to some of the
expected changes. There are two stages to impact assessment:
predicting what the consequences will be for ecosystem change
and human health, and assessing how important those changes
will be.
Even more speculative are the effects of extreme events: for
example, the worsening of El Niño, reserved.
Ecosystems change in response to climate change but, in
general, past changes have occurred slowly as temperatures
varied over long periods. A rise of 1 or 2° C in just a century is a
very fast rate of temperature change, and some ecosystems may
not be able to adjust

8. Listing possible impacts is one thing; saying how important they
are is another. Yet some idea of the collective magnitude of the
impacts is essential because the measures needed to reduce rates
of warming will not be cheap. Economic studies suggest a fairly
uniform measure of damage of about 1 to 2 per cent of the world’s
entire economic output. But this is a figure relating to “2 x
CO2”, that is, for a doubling of CO2 concentrations in the
atmosphere. It is a benchmark widely used for economic and
scientific analysis, but global US$30 perwill not stop there if
This figure is probably around warming tone, but with a fairly
unchecked, so uncertainty surrounding itfar future could be very
wide range of the damages in the very .
much higher.
As with virtually all aspects of the global warming debate, there
are many complications. First, it seems likely that the costs of
controlling carbon emissions now is fairly low for the first
tranche of emissions, but as more and more reduction occurs it
will become increasingly expensive to reduce emissions.

9. These widely varying views also explain the differences of opinion
about the adequacy of the actions already taken. It does not
benefit any single nation to take action unless it can be assured
others will act likewise. The disadvantages of being a “first
mover” explain why the subject has to be dealt with at the
international level, initially through the United Nations Framework
Convention on Climate Change (UNFCCC) in 1992 in Rio de
Janeiro, and subsequently at the Conference of Parties in Kyoto in
1997. The Kyoto Protocol, which emerged from the 1997
conference and came into force in February 2005, is the first
agreement under the UNFCCC with greenhouse gas emission
reduction targets that is binding in international law. The UNFCCC
itself set voluntary targets for industrialized nations such that their
CO2 emissions should be no higher in 2000 than they were in
1990. Developing countries argued that they had no