The Aerosol-Monsoon Climate System of Asia: Changes and Vulnerability
In an assessment of possible impacts on the Asian monsoon by aerosols compared to those by greenhouse gas (GHG) warming, we found that, on the large-scale, GHG warming alone can have both enhancing and limiting effects through differential heating of the land and ocean for monsoon precipitation and circulation, and that overall aerosols tend to suppress monsoon precipitation. Changes in regional monsoon precipitation are manifested as the residual effects of these two dominant, but opposing climate change agents. However, on a more local scale, aerosol may amplify GHG warming effects. Results will be presented showing that pre-monsoon accumulation of deep layer of absorbing aerosols (dust and black carbon) trapped by local topography may interact with monsoon dynamics, can exacerbate global warming effects via dynamical feedback processes, leading to re-distribution of monsoon rainfall, and increased vulnerability to climate change over specific regions in Asia. Examples included accelerated melting of high mountain glacier and snowpack, bursting of glacier lakes, disastrous flooding and mudslides, uprooting the livelihood of millions in the Himalayan foothills, the Sichuan Basin and other mountainous Asian monsoon regions with dense populations.