IPCC Co-Chair Updates Congressional Committee on Global Warming

Dr. Christopher Field of the Carnegie Institution for Science, and Co-chair of working group II of the Intergovernmental Panel on Climate Change (IPCC) briefed the Environment and Public Works Congressional Committee earlier this week on the latest global warming science.

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Here are some of the highlights from Field's testimony. Much of it includes the earlier consensus findings of from the 4th Assessment Report of the IPCC.

--Global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values determined from ice cores spanning many thousands of years.

--Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.

--Very high confidence that the global average net effect of human activities since 1750 has been one of warming.

--Global greenhouse gas (GHG) emissions have grown since pre-industrial times, with an increase of 70% between 1970 and 2004.

--Palaeoclimatic information supports the interpretation that the warmth of the last half century is unusual in at least the previous 1,300 years.

--Most of the observed increase in global average 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 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."

--For the next two decades, a warming of about 0.2°C per decade is projected for a range of SRES emission scenarios.

--Anthropogenic warming and sea level rise would continue for centuries due to the time scales associated with climate processes and feedbacks, even if greenhouse gas concentrations were to be stabilized.

--Drought-affected areas will likely increase in extent. Heavy precipitation events, which are very likely to increase in frequency, will augment flood risk.

--Many millions more people are projected to be flooded every year due to sea-level rise by the 2080s.

--Energy efficiency options for new and existing buildings could considerably reduce CO2 emissions with net economic benefit.

--In order to stabilize the concentration of GHGs in the atmosphere, emissions would need to peak and decline thereafter. The lower the stabilization level, the more quickly this peak and decline would need to occur. Mitigation efforts over the next two to three decades will have a large impact on opportunities to achieve lower stabilization levels.

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You can read the full testimony from Dr. Field right here.

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Major funding to Dr. Field and the Carnegie Institution for Science provided by the
Gordon and Betty Moore Foundation, Vannevar Bush Society, Edwin Hubble Society and the Carnegie Founders Society.