New Paper “Black Carbon Aerosols And The Third Polar Ice Cap” By Menon Et Al 2010

There is another paper that documents the major role of black carbon (soot) on the climate system (thanks to Marcel Severijnen for alerting us to it!).

The paper is

S. Menon, D. Koch, G. Beig, S. Sahu, J. Fasullo, and D. Orlikowski 2010: Black carbon aerosols and the third polar ice cap.  Atmos. Chem. Phys. Discuss., 9, 26593–26625, 2009 http://www.atmos-chem-phys-discuss.net/9/26593/2009/

The abstract reads

“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 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 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 ~30%, 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.”

The conclusion reads

“Although we do not preclude the influence of large-scale circulation or GHGs on the spatial patterns of precipitation or snow cover changes, our results indicate that aerosols and the enhanced Indian fossil/bio-fuel BC aerosols in particular may be responsible for some of the observed patterns and trends in snow/ice cover and precipitation. However, since we use prescribed SSTs in our simulations the climate response we simulate for the monsoon, especially near the ocean, may not fully account for feedbacks that occur when aerosols impact SSTs that could affect the spatial pattern of precipitation (Rotstayn and Lohmann, 2002). The range in climate impacts from the two emission inventories examined provide an estimate of the expected uncertainty in climate change from aerosols for the last decade (1990 to 2000) and illustrate future expected challenges from aerosols and BC emissions in particular. Preserving the present snow/ice cover on the third polar ice cap would require concerted efforts to reduce both GHGs and BC emissions from coal as well as transportation and residential
cooking/heating sources.”

[see also the news article about this paper at http://newscenter.lbl.gov/feature-stories/2010/02/03/black-carbon-himalayan-glaciers/]

This is yet another paper that documents that a wider perspective on the role of humans in the climate system is needed, as we recommend in our paper

Pielke Sr., R., K. Beven, G. Brasseur, J. Calvert, M. Chahine, R. Dickerson, D. Entekhabi, E. Foufoula-Georgiou, H. Gupta, V. Gupta, W. Krajewski, E. Philip Krider, W. K.M. Lau, J. McDonnell,  W. Rossow,  J. Schaake, J. Smith, S. Sorooshian,  and E. Wood, 2009: Climate change: The need to consider human forcings besides greenhouse gases. Eos, Vol. 90, No. 45, 10 November 2009, 413. Copyright (2009) American Geophysical Union

where we wrote

“In addition to greenhouse gas emissions, other first-order human climate forcings are important to understanding the future behavior of Earth’s climate. These forcings are spatially heterogeneous and include the effect of aerosols on clouds and associated precipitation [e.g., Rosenfeld et al., 2008], the influence of aerosol deposition (e.g., black carbon (soot) [Flanner et al. 2007] and reactive nitrogen [Galloway et al., 2004]), and the role of changes in land use/land cover [e.g., Takata et al., 2009]. Among their effects is their role in altering atmospheric and ocean circulation features away from what they would be in the natural climate system [NRC, 2005]. As with CO2, the lengths of time that they affect the climate are estimated to be on multidecadal time scales and longer.”

 

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