Global Warming: What You Need to Know

Intergovernmental Panel on Climate Change

An Overview

A Trajectory of Greater Certainty

The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to assess the "risk of human-induced climate change." The Panel is open to all members of the WMO and UNEP, and includes more than 2,500 scientists from around the world. In 2007, the IPCC was awarded the Nobel Peace Prize.

The IPCC does not carry out new research, nor does it monitor climate-related data. It bases its assessments on published and peer-reviewed scientific technical literature. The IPCC was created specifically to inform international policy and negotiations on climate issues. IPCC reports are the most comprehensive and reliable statement of what the world's scientists know about climate change.

In 2007, the IPCC released its Fourth Assessment Report (AR4) on global climate change. The AR4 is organized into three Working Group Reports covering the science, impacts & adaptation, and mitigation. In November 2007, the IPCC released its synthesis report of the three individual parts. This is the organization’s fourth report since 1990 on the science of global warming, and with each new report, the scientists have concluded that the certainty of a human effect on global climate has increased, while the likelihood of other factors playing a predominant role in observed warming has decreased.

In fact, the AR4 furthered the trajectory of scientific consensus on global warming, concluding with 90% or greater certainty that global warming is mainly caused by human activity:

"Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations. This is an advance since the TAR’s [Third Assessment Report’s] conclusion that ‘most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations’.” — Report of Working Group I, IPCC Fourth Assessment Report, 2007, Summary for Policy Makers, p. 10.

Significance

The IPCC Assessment reports synthesize existing research and information about our climate system and global warming, focusing only on published and peer-reviewed scientific technical literature. The rigor used to separate theory from fact is unprecedented, allowing the reports to clearly indicate what information is known with certainty, and what uncertainties still exist.

As the base of knowledge develops, findings that may have been questioned in the past may get renewed attention and inclusion in subsequent reports. This process reflects the IPCC's unique ability to use the peer-review-based foundation of scientific understanding to reach consensus on developing areas of concern.

More information about the IPCC and the Assessment reports can be found at www.ipcc.ch.

Next: Key Findings of the IPCC Fourth Assessment Report, 2007