Saving the Cryosphere in the Arctic and the Himalayas: Mitigation of Short Lived Climate Pollutants

Observations reveal that the polar warming is hastened by the pole ward retreat of the extra-tropical storm track clouds and the sea-ice albedo feedback. The cloud systems associated with the storm tracks are the dominant radiative cooling cloud systems in the planet and their retreat adds more solar energy to the extra-tropical oceans. This is further amplified by the observed reduction in the arctic albedo due to the retreat of the sea-ice. Complicating this situation is the darkening of the arctic cryosphere by black carbon deposition. Over the Himalayas on the other hand, the thermo dynamical feedback involving water vapor amplifies surface warming over the elevated regions of Himalayas-Tibet by factors ranging from1 .5 to 2. This elevated warming is further amplified by black carbon in two distinctly different ways: First absorption of solar radiation in the atmosphere by black carbon has been shown to warm the layers above 5 km by as much as the warming due to CO2. Next, long range transport of black carbon, leads to deposition of black carbon over the bright snow and ice darkens them and enhances the absorption of intense tropical solar radiation over the Himalayas. After summarizing recent observations over the arctic and the Himalayas, we will show how mitigation of the four short lived climate pollutants (methane, black carbon, ozone and HFCs) can significantly slow down the arctic warming and the large warming observed over the elevated regions of the Himalayas-Tibet.