Evidence of Human-Caused Global Warming Unequivocal

PARIS, France, February 2, 2007 (ENS) - Changes in the atmosphere, the oceans, glaciers and ice caps show unequivocally that the Earth is warming, according to the first global assessment of climate change science in six years.

The report confirms that the observed increase in atmospheric concentrations of greenhouse gases carbon dioxide, methane, and nitrous oxide since 1750 is the result of human activities.


Greenhouse gases rise into the air from Russias largest coal-fired power plant, Reftinskaya GRES. (Photo courtesy RAO UESR)
The Intergovernmental Panel on Climate Change, IPCC, concludes that advances in climate modeling and the collection and analysis of data now give scientists 90 percent confidence in their understanding of how human activities are causing the world to warm.

This level of confidence is much greater than what could be achieved in 2001 when the IPCC issued its last assessment.

Introducing the report today in Paris, Dr. Susan Solomon, an American atmospheric chemist, said it is "very likely," a 90 percent probability, that most of the observed increase in temperatures is due to the observed increase in greenhouse gas concentrations.


Dr. Susan Solomon works with the National Oceanic and Atmospheric Administration at with the University of Colorado at Boulder. (Photo courtesy CHF)
The 2001 assessment said it was "likely," a probability of 66 percent.

The rapid rise in global concentrations of carbon dioxide, methane and nitrous oxide, all greenhouse gases, is so different from the patterns for thousands of years previous, "there is no doubt that increase is dominated by human activity," said Solomon, who helped to identify the mechanism that created the Antarctic ozone hole.

IPCC Chairman Dr. R.K. Pachauri of India called the entire process of preparing the document, the first of four to be released this year by the panel, "a unique example of science in the service of society."

He said 600 authors from 40 countries worked on the report, which was then assessed by 600 reviewers. Over the past several days, the whole thing was discussed by 300 delegations from 113 countries meeting in Paris.


IPCC Chairman Dr. R.K. Pachauri (Photo courtesy US Climate Change Science Program)
"This is the strength of the IPCC process," said Dr. Pachauri. The scientists provide the knowledge, this is discussed and adopted by governments. It provides credibility."

The report describes an accelerating transition to a warmer world marked by more extreme temperatures, heat waves, new wind patterns, worsening drought in some regions, heavier precipitation in others, melting glaciers and Arctic ice, and rising global average sea levels.

For the first time, the report provides evidence that the ice sheets of Antarctica and Greenland are losing mass and contributing to sea level rise.

An even greater degree of warming would likely have occurred if emissions of pollution particles and other aerosols had not offset some of the impact of greenhouse gases, by reflecting sunlight back out to space, the scientists said.

Solomon said the concentrations of greenhouse gases already in the atmosphere will continue to warm the planet for centuries, even if humans stabilize emissions within the next 10 years.

"This report by the IPCC represents the most rigorous and comprehensive assessment possible of the current state of climate science and has considerably narrowed the uncertainties of the 2001 report," said Michel Jarraud, secretary general of the World Meteorological Organization, WMO.


Michel Jarraud, secretary general of the World Meteorological Organization (Photo courtesy UCAR)
"While the conclusions are disturbing, decision makers are now armed with the latest facts and will be better able to respond to these realities," Jarraud said.

"The speed with which melting ice sheets are raising sea levels is uncertain, but the report makes clear that sea levels will rise inexorably over the coming centuries. It is a question of when and how much, and not if," he said.

"In our daily lives we all respond urgently to dangers that are much less likely than climate change to affect the future of our children," said Achim Steiner, executive director of the United Nations Environment Programme, UNEP, which, together with the WMO, established the Intergovernmental Panel on Climate Change in 1988.

"February 2nd will be remembered as the date when uncertainty was removed as to whether humans had anything to do with climate change on this planet," said Steiner. "We are looking for an unequivocal response from politicians. The evidence is on the table, we no longer have to debate that part of it."

"Nine thousand children will be born worldwide during this one hour press conference," said Steiner, and it differs where you are born. African chidlren will be faced with new diseases, new droughts, may have to leave their homes because Africa may have 30 percent of its coastal infrastructure destroyed by sea level rise.


Achim Steiner is executive director of the United Nations Environment Programme. (Photo courtesy Earth Negociations Bulletin)
Many Asians will be turned into environmental refugees as rising sea levels claim their lands, Steiner warned.

"The implications of global warming over the coming decades for our industrial economy, water supplies, agriculture, biological diversity and even geopolitics are massive," he said.

"Momentum for action is building," Steiner said. "This new report should spur policymakers to get off the fence and put strong and effective policies in place to tackle greenhouse gas emissions."

The IPCC Working Group I report, "The Physical Science Basis," concludes that:

The Intergovernmental Panel on Climate Change does not conduct new research. Instead, its mandate is to make policy relevant assessments of the existing worldwide literature on the scientific, technical and socio-economic aspects of climate change.

Its reports have played a major role in inspiring governments to adopt and implement the United Nations Framework Convention on Climate Change and the Kyoto Protocol.

The Summary for Policymakers for IPCC Working Group I, which was finalized line-by-line by governments during the course of this week, has now been posted in English at www.ipcc.ch. The full underlying report "Climate Change 2007: The Physical Science Basis" will be published by Cambridge University Press.

The Working Group II report on climate impacts and adaptation will be launched in Brussels on April 6.

The Working Group III report on mitigation will be launched in Bangkok on May 4.

A Synthesis Report will be adopted in Valencia, Spain on November 16. Dr. Pachauri says this 30 page synthesis of the three Working Group reports will make it possible for a prime minister, a president or a CEO to understand it during a train ride from Paris to Brussels or wherever they are travelling.

Together, the four volumes will make up the IPCCs fourth assessment report. Previous reports were published in 1990, 1995 and 2001.