There is, in fact, a broad and overwhelming scientific consensus that climate change is occurring, is caused in large part by human activities (such as burning fossil fuels), and if left un-checked will likely have disastrous consequences.
Furthermore, there is solid scientific evidence that we should act now
on climate change - and this is reflected in the statements by these
definitive scientific authorities.
Joint statement from 11 national academies of science
Issued 7 June 2005, by the national science academies of the United
States, United Kingdom, France, Russia, Germany, Japan, Italy, Canada,
Brazil, China and India, the statement begins with:
Climate change is real
There will always be uncertainty in understanding a system as complex
as the world’s climate. However there is now strong evidence that
significant global warming is occurring. The evidence comes from direct
measurements of rising surface air temperatures and subsurface ocean
temperatures and from phenomena such as increases in average global sea
levels, retreating glaciers, and changes to many physical and
biological systems. It is likely that most of the warming in recent
decades can be attributed to human activities (IPCC 2001). This warming
has already led to changes in the Earth's climate.
The statement goes on to conclude:
We urge all nations, in the line with the UNFCCC
principles, to take prompt action to reduce the causes of
climate change, adapt to its impacts and ensure that the
issue is included in all relevant national and international
strategies.
Full text of statement on NAS website (pdf)
Royal Society - climate change
Intergovernmental Panel on Climate Change
The Intergovernmental Panel on Climate Change (IPCC) was set up by the
United Nations in 1988 to assess the scientific, technical and
socio-economic information relevant for the understanding of the risk
of human induced climate change. About 1,000 experts from around
the world are involved in drafting, revising and finalizing IPCC
reports. About 2,500 experts take part in the report review
process. Thus, the IPCC represents a global consensus
of the world's climate change experts. From the IPCC's most
recent scientific assessment:
“[M]ost of the observed warming over the last 50
years is likely to have been due to the increase in greenhouse gas
concentrations".
- "There is new and stronger evidence that most of
the observed warming over the last 50 years is attributable to human
activities".
- "About three quarters of the anthropogenic [human
caused] emissions of CO2 to the atmosphere during the past 20 years are
due to fossil fuel burning”.
The assessment goes on to warn that there is a risk of feedback loops,
which could cause runaway climate change, and that the global warming
to date is already having an effect on the biosphere.
More about the
IPCC
Greenpeace briefing paper on the IPCC Third Assessment Report
(pdf)
Intergovernmental Panel on Climate Change (IPCC)