Global Warming: IPCC's Fourth Assessment Report

Global Warming: IPCC's Fourth Assessment Report

The Intergovernmental Panel on Climate Change (IPCC) published a series of reports in 2007 that set forth conclusions about the causes and effects of global warming as well as the costs and benefits of solving the problem.

The reports, which drew on the work of more than 2,500 of the world's leading climate scientists and were endorsed by 130 nations, confirmed the consensus of scientific opinion on the key questions related to global warming.

Taken together, the reports are intended to help policymakers worldwide make informed decisions and develop effective strategies to reduce greenhouse gas emissions and control global warming.

What Is the Purpose of the IPCC?

The IPCC was established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to provide a comprehensive and objective assessment of scientific, technical and socio-economic information that could lead to a better understanding of human-induced climate change, its potential impacts, and the options for adaptation and mitigation. The IPCC is open to all members of the United Nations and the WMO.

The Physical Basis of Climate Change

On February 2, 2007, the IPCC published a summary report from Working Group I, which confirms that global warming is now “unequivocal” and states with more than 90 percent certainty that human activity “very likely” has been the primary cause of rising temperatures worldwide since 1950.

The report also says that global warming is likely to continue for centuries and that it is already too late to stop some of the serious consequences it will bring. Still, the report also says there is still time to slow global warming and to lessen many of its most severe consequences if we act quickly.

Climate Change 2007: Impacts, Adaptation, and Vulnerability

The effects of global warming in the 21st century and beyond are expected to be disastrous, according to the summary of a scientific report issued on April 6, 2007, by Working Group II of the IPCC. And many of those changes are already under way.

This also makes it clear that while poor people worldwide will suffer most from the effects of global warming, no person on Earth will escape its consequences. The effects of global warming will be felt in every region and at all levels of society.

Climate Change 2007: Mitigation of Climate Change

On May 4, 2007, Working Group III of the IPCC released a report showing that the cost of controlling greenhouse gas emissions worldwide and avoiding the most serious effects of global warming is affordable and would be partially offset by economic gains and other benefits. This conclusion refutes the argument of many industry and government leaders who say that taking serious action to reduce greenhouse gas emissions would lead to economic ruin.

In this report, scientists outline the costs and benefits of strategies that could reduce global warming over the next few decades. And while controlling global warming will require significant investment, the consensus of scientists who worked on the report is that nations have no choice but to take immediate action.

“If we continue doing what we are doing now, we are in deep trouble,” said Ogunlade Davidson, co-chair of the working group that produced the report.