Global Warming "Very Likely" Caused by Humans, World Climate Experts Say

February 2, 2007

Global warming is here, it's human-caused, and it will continue for centuries even if greenhouse-gas emissions are stabilized, an international panel of climate experts said in a report issued today.

The Intergovernmental Panel on Climate Change (IPCC) used its strongest language yet to link human activity to Earth's warming temperatures, rising seas, more intense storms, and a host of other environmental maladies.

"Fossil fuel use, agriculture, and land-use change are fundamentally affecting the systems on our planet," Achim Steiner, executive director of the United Nations Environment Programme, said at a press briefing in Paris, France.

(Get the basics: "Global Warming Fast Facts.")

The United Nations and the World Meteorological Organization oversee the IPCC.

Hundreds of climate experts and government representatives from 113 countries labored all week in Paris to reach unanimous agreement on the wording of each sentence in the 20-page summary for policymakers.

"Most of the observed increase in globally averaged temperature since the mid-20th century is very likely due to the observed increase in anthropogenic [human-caused] greenhouse gas concentrations," the report reads.

"Very Likely" a Big Step

The phrase "very likely" translates to a 90 percent probability, the report's authors note. This is a significant departure from previous reports.

In 2001 the panel concluded humans were "likely," or with 66 percent probability, the cause of global warming. The panel also released reports in 1995 and 1990.

"Each time they've used a more explicit statement about the human contribution," said Henry Jacoby, co-director of the Center for Energy and Environmental Policy Research at the Massachusetts Institute of Technology, in a phone interview Thursday.

Jacoby, who studies the threat of global climate change, said the report will cause some people to "be somewhat more concerned" but doubted it would be "revolutionary" in spurring action to reduce greenhouse gas emissions.

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