Airborne soot's heating effects have been found to be 60 percent of CO2's, yielding a 40/60 soot/CO2 global atmospheric heating combination. In higher altitudes soot is just as important as CO2 in melting tropical glacial packs like the Himalayas (and perhaps Kilimanjaro) while also devasting Arctic ice by making it more heat-absorbant.
INDOEX lead researcher V. Ramanathan has co-authored a paper on his team's findings that airborne soot (aka black carbon, or BC for short) plays a far greater role in atmospheric warming than the UN's IPCC reports have yet indicated.
Ramanathan and his team at the Scripps Oceanographic Institute are renown for their INDOEX work for NASA and the IPCC. In recent field studies (Aug. 2007) they collected direct airborne samples and applied the results to existing climate models. Much to their surprise they found that - contrary to conventional opinion - airborne soot has a net atmospheric heating effect (instead of a net cooling effect).
Since August 2007 Ramanathan & Carmicheal have further honed their findings and released another startling paper published March 2008 in Nature. Their findings indicate that airborne tropospheric soot contributes roughly 35 - 40 percent of all observed temperature anomalies (roughly a 37-57 soot-CO2 ratio). This is very similar to the net mix I had estimated last year.
"...The report concludes that the atmospheric warming effect of black
carbon pollution is as much as three to four times the consensus
estimate [emphasis mine] released last year in a report by the
U.N.-sponsored Intergovernmental Panel on Climate Change."
"...The paper concludes that carbon pollution contributes to global
warming at a level that is about 60% of carbon dioxide's warming
"...A mass of black carbon in the atmosphere causes about 300,000 times
as much instantaneous warming as the same amount of carbon dioxide."
Ramanathan's co-authored paper appeared in Nature Geoscience 1, 221 - 227 (2008 - Published online: 23 March 2008) is titled "Global and regional climate changes due to black carbon." The abstract reads as follows:
"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."
With regard to glacier packs, it's been found that industrial soot may be
eight times (8x) more effective at melting snow than that from burning wood fuels. [I'll provide a citation on that later]
link: http://www.science20.com/news/industrial_soot_and_its_arctic_impact .
|Note: I'll have to recant the "8x" claim just a bit here (sometimes memory disserves...): The McDonnel/Edwards study of industrial soot doesn't explicitly claim industrial soot being 8x more effective at melting snow, just that its historical effect in the early 20th Century was 8 times greater than preindustrial times. The article clearly implies, however, that the effect of industrial soot is far more pernicious than soot from wood fuels. This has substantial policy implications considering the majority of soot currently falling on the Arctic is from S. E. Asia.|
The full text & PDF versions of Ramanathan's paper can be found at: