reducing such emissions may be "the most efficient way to mitigate Arctic warming that we know of". The "climate forcing due to snow/ice albedo change is of the order of 1.0 W/m2 at middle- and high-latitude land areas in the Northern Hemisphere and over the Arctic Ocean." The "soot effect on snow albedo may be responsible for a quarter of observed global warming." "Soot deposition increases surface melt on ice masses, and the meltwater spurs multiple radiative and dynamical feedback processes that accelerate ice disintegration," according to NASA scientists James Hansen and Larissa Nazarenko. As a result of this feedback process, "BC on snow warms the planet about three times more than an equal forcing of CO2." When black carbon concentrations in the Arctic increase during the winter and spring due to Arctic Haze, surface temperatures increase by 0.5 °C. Black carbon emissions also significantly contribute to Arctic ice-melt, which is critical because "nothing in climate is more aptly described as a 'tipping point' than the 0 °C boundary that separates frozen from liquid water—the bright, reflective snow and ice from the dark, heat-absorbing ocean." Black carbon emissions from northern Eurasia, North America, and Asia have the greatest absolute impact on Arctic warming. However, black carbon emissions actually occurring within the Arctic have a disproportionately larger impact per particle on Arctic warming than emissions originating elsewhere. As Arctic ice melts and shipping activity increases, emissions originating within the Arctic are expected to rise. In some regions, such as the Himalayas, the impact of black carbon on melting snowpack and glaciers may be equal to that of CO2. Warmer air resulting from the presence of black carbon in South and East Asia over the Himalayas contributes to a warming of approximately 0.6 °C. An "analysis of temperature trends on the Tibetan side of the Himalayas reveals warming in excess of 1 °C." A summer aerosol sampling on a glacier saddle of Mt. Everest (Qomolangma) in 2003 showed industrially induced sulfate from South Asia may cross over the highly elevated Himalaya. This indicated BC in South Asia could also have the same transport mode. And such kind of signal might have been detected in at a black carbon monitoring site in the hinterland of Tibet. Snow sampling and measurement suggested black carbon deposited in some Himalayan glaciers may reduce the surface albedo by 0.01–0.02. Black carbon record based on a shallow ice