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Black Carbon and the Melting of Himalayan Glaciers
Kopacz, M., Mauzerall, D.L., Wang, J., Leibensperger, E.M., Henze, D.K. and Singh, K. 2011. Origin and radiative forcing of black carbon transported to the Himalayas and Tibetan Plateau. Atmospheric Chemistry and Physics 11: 2837-2852.

The authors write that "the Himalayas and the Tibetan Plateau, also collectively known as the Third Pole, represent a large area of seasonal and permanent snow cover," which is "surrounded by growing emissions of Asian air pollutants," and they say that observations of black carbon (BC) content in snow "show a rapidly increasing trend," citing the work of Xu et al. (2009).

What was done
Kopacz et al. used a global chemical transport model to identify the location from which the BC arriving at a variety of locations in the Himalayas and the Tibetan Plateau originates, after which they calculated its direct and snow-albedo radiative forcings.

What was learned
The six U.S. scientists determined that "emissions from northern India and central China contribute the majority of BC to the Himalayas," and that "the Tibetan Plateau receives most BC from western and central China, as well as from India, Nepal, the Middle East, Pakistan and other countries." In addition, they report that the radiative forcing due to the direct effect of BC at five glacier sites has "a global annual mean of +0.32 W/m2, while "the local monthly mean radiative forcing due to changes in snow-albedo ranges from +3.78 to +15.6 W/m2."

What it means
Clearly, the current snow-albedo-altering impact of BC wafting over the Himalayas and the Tibetan Plateau vastly overshadows its direct radiative warming impact, which suggests that the most logical way to strive to avert the melting of Himalayan glaciers would be to reduce Asian BC emissions, which would also have a huge positive impact on the health of people living throughout this part of the world, particularly since Ramanathan and Carmichael (2008) note that the majority of BC emissions (60%) arise from "cooking with biofuels such as wood, dung and crop residue" and from "open biomass burning (associated with deforestation and crop residue burning)," and since Venkataraman et al. (2005) note that control of BC emissions through cleaner cooking technologies alone could help in "reducing health risks to several hundred million users."

Ramanathan, V. and Carmichael, G. 2008. Global and regional climate changes due to black carbon. Nature Geoscience 1: 221-227.

Venkataraman, C., Habib, G., Eiguren-Fernandez, A., Miguel, A.H. and Friedlander, S.K. 2005. Residential biofuels in South Asia: Carbonaceous aerosol emissions and climate impacts. Science 307: 1454-1456.

Xu, B.-Q., Wang, M., Joswiak, D.R., Cao, J.-J., Yao, T.-D., Wu, G.-J., Yang, W. and Zhao, H.-B. 2009. Deposition of anthropogenic aerosols in a southeastern tibetan glacier. Journal of Geophysical Research 114: 10.1029/2008JD011510.

Reviewed 18 May 2011