Black carbon aerosols and the third polar ice cap S. Menon1, D. Koch2, G. Beig3, S. Sahu3, J. Fasullo4, and D. Orlikowski5 1Lawrence Berkeley National Laboratory, Berkeley, CA, USA 2Columbia University/NASA GISS, New York, NY, USA 3Indian Institute for Tropical Meteorology, Pune, India 4Climate Analysis Section, CGD/NCAR, Boulder, CO, USA 5Lawrence Livermore National Laboratory, Livermore, CA, USA
Abstract. Recent thinning of glaciers over the Himalayas (sometimes referred to as the
third polar region) have raised concern on future water supplies since these
glaciers supply water to large river systems that support millions of people
inhabiting the surrounding areas. Black carbon (BC) aerosols, released from
incomplete combustion, have been increasingly implicated as causing large
changes in the hydrology and radiative forcing over Asia and its deposition
on snow is thought to increase snow melt. In India BC emissions from biofuel
combustion is highly prevalent and compared to other regions, BC aerosol
amounts are high. Here, we quantify the impact of BC aerosols on snow cover
and precipitation from 1990 to 2010 over the Indian subcontinental region
using two different BC emission inventories. New estimates indicate that
Indian BC emissions from coal and biofuel are large and transport is expected
to expand rapidly in coming years. We show that over the Himalayas, from 1990
to 2000, simulated snow/ice cover decreases by ~0.9% due to aerosols.
The contribution of the enhanced Indian BC to this decline is ~36%,
similar to that simulated for 2000 to 2010. Spatial patterns of modeled
changes in snow cover and precipitation are similar to observations (from
1990 to 2000), and are mainly obtained with the newer BC estimates.
Citation: Menon, S., Koch, D., Beig, G., Sahu, S., Fasullo, J., and Orlikowski, D.: Black carbon aerosols and the third polar ice cap, Atmos. Chem. Phys., 10, 4559-4571, doi:10.5194/acp-10-4559-2010, 2010.