Archive for the ‘IPCC’ Category

Black Carbon — New Report

March 25, 2008

A new report was published on line this weekend at Nature Geoscience:

Nature Geoscience
Published online: 23 March 2008 | doi:10.1038/ngeo156

Global and regional climate changes due to black carbon
V. Ramanathan1 & G. Carmichael2

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Abstract:

Black carbon in soot is the dominant absorber of visible solar radiation in the atmosphere. Anthropogenic sources of black carbon, although distributed globally, are most concentrated in the tropics where solar irradiance is highest. Black carbon is often transported over long distances, mixing with other aerosols along the way. The aerosol mix can form transcontinental plumes of atmospheric brown clouds, with vertical extents of 3 to 5 km. Because of the combination of high absorption, a regional distribution roughly aligned with solar irradiance, and the capacity to form widespread atmospheric brown clouds in a mixture with other aerosols, emissions of black carbon are the second strongest contribution to current global warming, after carbon dioxide emissions. In the Himalayan region, solar heating from black carbon at high elevations may be just as important as carbon dioxide in the melting of snowpacks and glaciers. The interception of solar radiation by atmospheric brown clouds leads to dimming at the Earth’s surface with important implications for the hydrological cycle, and the deposition of black carbon darkens snow and ice surfaces, which can contribute to melting, in particular of Arctic sea ice.

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The paper concluded that black carbon’s warming effect in the atmosphere is about 0.9 watts per meter squared, compared with IPCC’s consensus estimate of 0.2 to 0.4 watts.

“The positive side of this discouraging story is we know how to cut down black carbon,” Ramanathan said. “We have reduced it. So this is something we can do now.”
(Los Angeles Times, 25 March 2008 )

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What’s the Buzz?

March 2, 2008

 Quotes from the  public unveiling of the Synthesis Report of the Intergovernmental Panel on Climate Change (IPCC), Valencia, Spain, Nov 19 2007:

“We are riding in an airplane with the bolts falling out while heading into a storm.” Stephen Tonser (2007), ecologist, University of Pittsburgh

“Climate change is going faster than our worst-case scenarios of five or six years ago.” Hans Verolme (2007), director of the climate change program for the World Wildlife Fund

“The IPCC has greatly underestimated the climate storm ahead.  When all the earth systems are taken into account an atmospheric concentration of 500 ppm of CO2 will result in a six degree rise in global temperatures, not the two degrees Celsius the IPCC says is most likely. ” Dr. James Lovelock (2007)