large forcing because of a positive feedback: Reduced snow albedo would increase surface temperature. The increased surface temperature would decrease the snow cover and further decrease surface albedo. Indirect effect Black carbon may also indirectly cause changes in the absorption or reflection of solar radiation through changes in the properties and behavior of clouds. Research scheduled for publication in 2013 shows black carbon plays a role second only to carbon dioxide in climate change. Effects are complex, resulting from a variety of factors, but due to the short life of black carbon in the atmosphere, about a week as compared to carbon dioxide which last centuries, control of black carbon offers possible opportunities for slowing, or even reversing, climate change. Radiative forcing Estimates of black carbon's globally averaged direct radiative forcing vary from the IPCC's estimate of + 0.34 watts per square meter (W/m2) ± 0.25, to a more recent estimate by V. Ramanathan and G. Carmichael of 0.9 W/m2. The IPCC also estimated the globally averaged snow albedo effect of black carbon at +0.1 ± 0.1 W/m2. Based on the IPCC estimate, it would be reasonable to conclude that the combined direct and indirect snow albedo effects for black carbon rank it as the third largest contributor to globally averaged positive radiative forcing since the pre-industrial period. In comparison, the more recent direct radiative forcing estimate by Ramanathan and Carmichael would lead one to conclude that black carbon has contributed the second largest globally averaged radiative forcing after carbon dioxide (CO2), and that the radiative forcing of black carbon is "as much as 55% of the CO2 forcing and is larger than the forcing due to the other greenhouse gasses (GHGs) such as CH4, CFCs, N2O, or tropospheric ozone." Table 1: Estimates of Black Carbon Radiative Forcing, by Effect Table 2: Estimated Climate Forcings (W/m2) Effects on Arctic ice and Himalayan glaciers According to the , "the presence of black carbon over highly reflective surfaces, such as snow and ice, or clouds, may cause a significant positive radiative forcing." The IPCC also notes that emissions from biomass burning, which usually have a negative forcing, have a positive forcing over snow fields in areas such as the Himalayas. A 2013 study quantified that gas flares contributed over 40% of the black carbon deposited in the Arctic. According to Charles Zender, black carbon is a significant contributor to Arctic ice-melt, and