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Working Group II Definitions

Likelihood of an outcome or result
Virtually certain > 99% probability of occurrence
Extremely likely > 95%
Very likely > 90%
Likely > 66%
More likely than not > 50%
Very unlikely < 10%
Extremely unlikely < 5%.

Confidence in a statement
Very high confidence: At least a 9 out of 10 chance of being correct
High confidence: About an 8 out of 10 chance
Medium confidence: About a 5 out of 10 chance
Low confidence: About a 2 out of 10 chance
Very low confidence: Less than a 1 out of 10 chance

Confidence symbols in the text
*** Very high confidence
** High confidence
* Medium confidence

Key Assumptions

The Working Group II report discusses future impacts "for the range of unmitigated climate changes projected by the IPCC over this century judged to be relevant for people and the environment." Its different scenarios of future emissions of greenhouse gases "do not include additional climate initiatives, which means that no scenarios are included that explicitly assume implementation of the United Nations Framework Convention on Climate Change or the emissions targets of the Kyoto Protocol."

Download MP3 recording of Science Briefing for Broadcast Meteorologists, Aug. 24, 2007
Read transcript of Science Briefing for Broadcast Meteorologists, Aug. 24, 2007

Media Advisory

Extreme Summer Weather and Global Warming:
Climate Science Briefing for Broadcast Meteorologists

A teleconference for broadcast meteorologists featuring leading U.S. climate scientists who participated in drafting the recent scientific consensus statements on the nature of global warming and its impact on weather was held on Friday, Aug. 24, 2007, at 2 p.m. EDT (11 a.m. PDT). The speakers addressed their reports published by the Intergovernmental Panel on Climate Change (IPCC) and approved by the U.S. government, including the latest scientific research and consensus statements on how climate change is affecting summer weather extremes, such as heat waves and hurricanes. The call was moderated by Dr. Robert Corell, Senior Policy Fellow for the American Meteorological Society (AMS), and included Paul Gross, Chair of the AMS's Station Scientist Committee.

In 2007, the IPCC published its Fourth Assessment Report, written by a team of hundreds of scientists and reviewed by both governments and scientific experts. The report, available online at http://www.ipcc.ch, is a definitive and up-to-date summary of the science of climate change, including what is known and what remains to be learned about the links between global warming and extreme weather.

When: Friday, Aug. 24, 2007, at 2:00 p.m. EDT

Teleconference number: 1-800-290-9461, Passcode 23821

Panelists:

Paul Gross, C.C.M., Chair of AMS's Station Scientist Committee; Broadcast Meteorologist at WDIV-TV, Detroit

Dr. Gerald Meehl, Senior Scientist, Climate and Global Dynamics Division,
National Center for Atmospheric Research, Boulder, Colorado; IPCC Coordinating Lead Author, Working Group I, Global Climate Projections

Dr. Richard Somerville, Distinguished Professor Emeritus, Scripps Institution of Oceanography, University of California at San Diego; IPCC Coordinating Lead Author, Working Group I, Historical Overview of Climate Change Science

Dr. Kevin Trenberth, Head of the Climate Analysis Section, National Center for Atmospheric Research; IPCC Coordinating Lead Author, Working Group I, Observations: Surface and Atmospheric Climate Change

Moderator: Dr. Robert Corell, Senior Policy Fellow at the Policy Program of the American Meteorological Society and Global Change Program Director at the H. John Heinz III Center for Science, Economics and the Environment

Funding for the science briefing is provided by the William and Flora Hewlett Foundation and the Rockefeller Brothers Fund. The teleconference is a service of Resource Media, a 501 (c) (3) nonprofit organization.

Contact:
Jillian Ward, Resource Media, 415-397-5000 ext. 309, or
Hunter Cutting, Resource Media, 415-397-5000 ext. 315




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