Effects of black carbon and mineral dust on glacial melting on the Muz Taw glacier, Central Asia.

ABSTRACT

Light-absorbing impurities (LAIs), including black carbon (BC) and mineral dust, in snow can trigger a positive feedback. In this study, we estimate the contribution of BC and dust to glacial melting in Central Asia. Average BC and dust concentrations in the surface snow of the Muz Taw glacier are 1788 ± 1754 ng g-1 and 172 ± 178 µg g-1, respectively. Simulation using the Snow Ice and Aerosol Radiation (SNICAR) model indicates that the combined effect of BC and dust reduces the snow albedo by approximately 6.24% to 50.4% relative to clean snow. Radiative forcing (RF) induced by BC and dust deposited in snow ranges from 1.61 to 32.69 W m-2, with an average of 16.74 W m-2 for the central scenario. Thus, glacier melting can be enhanced by 36.37 cm w.e. by BC and dust in snow, accounting for about 16.3% of the total glacier melt. LAIs deposited on the Muz Taw glacier mostly originate from Central Asia, West Siberia and local emissions during the study period. More than 80% of BC deposited is attributed to anthropogenic emissions. These results strengthen the important role of BC and dust in glacier melting in Central Asia, and further highlights the potential benefits of mitigation of BC emissions.