Vested interests have tried to spread
misinformation about global warming, but scientific evidence shows
urgent action is needed.Many people ask how sure we are about the
science of climate change. The most definitive examination of the
scientific evidence is to be found in the work of the
Intergovernmental Panel on Climate Change (IPCC) and its last major
report published in 2007. I had the privilege of being chairman or
co-chairman of the panel's scientific assessments from 1988 to 2002.
Many hundreds of scientists from different countries were involved
as contributors and reviewers for these reports, which are probably
the most comprehensive and thorough international assessments on any
scientific subject ever carried out. In June 1995, just before the
G8 summit in Scotland, the academies of science of the world's 11
largest economies (the G8 plus India, China, and Brazil) issued a
statement endorsing the IPCC's conclusions and urging world
governments to take urgent action to address climate change. The
world's top scientists could not have spoken more strongly.
Unfortunately, strong vested interests have spent millions of
dollars on spreading misinformation about climate change. First,
they tried to deny the existence of any scientific evidence for
global warming. More recently, they have largely accepted the fact
of anthropogenic (man-made) climate change but argue that its
impacts will not be great, that we can "wait and see," and that in
any case we can always fix the problem if it turns out to be
substantial.
The scientific evidence does not support such arguments. Urgent
action is needed both to adapt to the climate change that is
inevitable and to reduce emissions of greenhouse gases, especially
CO², to prevent further damage as far as possible.
At the Earth summit in Rio de Janeiro in 1992, the world's nations
signed up to the Framework Convention on Climate Change (FCCC), the
objective of which is "to stabilise the concentration of greenhouse
gases in the atmosphere at a level that does not cause dangerous
interference with the climate system … that allows ecosystems to
adapt naturally to climate change, that ensures food production is
not threatened, and that enables economic development to proceed in
a sustainable manner." Such stabilisation would also eventually stop
further climate change.
It is now recognised that widespread damage due, for instance, to
sea level rise and more frequent and intense heat waves, floods and
droughts, will occur even for small increases of global average
temperature. Therefore it is necessary that very strong efforts be
made to hold the average global temperature rise below 2C relative
to its preindustrial level.
If we are to have a good chance of achieving that target, the
concentration of CO² must not be allowed to exceed 450 parts per
million (it is now nearly 390 ppm). This implies that before 2050
global emissions of CO² must be reduced to below 50% of the 1990
level (they are currently 15% above that level), and that average
emissions in developed countries must be reduced by at least 80% of
the 1990 level. The UK has already committed itself to a binding
target to reduce emissions by that amount, and President Barack
Obama has expressed intention that the United States should also set
that target.
One clear requirement is that tropical deforestation, which is
responsible for 20% of greenhouse gas emissions, be halted within
the next decade or two. Regarding emissions from the burning of
fossil fuels, the International Energy Agency (IEA) in its Energy
Technology Perspectives has set out in detail the technologies and
actions that are needed in different countries and sectors to meet
these targets.
For the short term, the IEA points out that very strong and
determined action will be necessary to ensure that global CO²
emissions stop rising (the current increase is more than 3% per
year), reach a peak by about 2015, and then decline steadily toward
the 2050 target. The IEA also points out that the targets can be
achieved without unacceptable economic damage. In fact, the IEA
lists many benefits that will be realised if its recommendations are
followed.
What is required now is recognition that anthropogenic climate
change will severely affect our children, grandchildren, the world's
ecosystems, and the world's poorer communities, and that the
severity of the impact can be substantially alleviated by taking
action now.
John Theodore Houghton, a former professor of atmospheric physics at
Oxford University, and founder of the Hadley Centre for Climate
Prediction and Research, was the co-chair of the IPCC's scientific
assessment working group and lead editor of its first three reports
Copyright: Project Syndicate, 2009.
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