Impact of anthropogenic absorbing aerosols on clouds and precipitation : A review of recent progresses *

The MIT Joint Program on the Science and Policy of Global Change combines cutting-edge scientific research with independent policy analysis to provide a solid foundation for the public and private decisions needed to mitigate and adapt to unavoidable global environmental changes. Being data-driven, the Program uses extensive Earth system and economic data and models to produce quantitative analysis and predictions of the risks of climate change and the challenges of limiting human influence on the environment—essential knowledge for the international dialogue toward a global response to climate change. To this end, the Program brings together an interdisciplinary group from two established MIT research centers: the Center for Global Change Science (CGCS) and the Center for Energy and Environmental Policy Research (CEEPR). These two centers—along with collaborators from the Marine Biology Laboratory (MBL) at Woods Hole and short-and long-term visitors—provide the united vision needed to solve global challenges. At the heart of much of the Program's work lies MIT's Integrated Global System Model. Through this integrated model, the Program seeks to: discover new interactions among natural and human climate system components; objectively assess uncertainty in economic and climate projections; critically and quantitatively analyze environmental management and policy proposals; understand complex connections among the many forces that will shape our future; and improve methods to model, monitor and verify greenhouse gas emissions and climatic impacts. This reprint is one of a series intended to communicate research results and improve public understanding of global environment and energy challenges, thereby contributing to informed debate about climate change and the economic and social implications of policy alternatives. a r t i c l e i n f o a b s t r a c t The climate impact of anthropogenic absorbing aerosols has attracted wide attentions recently. The unique forcing distribution of these aerosols displays, as instantaneous and in solar band, a significant heating to the atmosphere and a cooling in a close but smaller magnitude at the Earth's surface, leading to a positive net forcing to the Earth-atmosphere system, i.e., the forcing at the top of the atmosphere, which brings a warming tendency to the climate system. On the other hand, the atmospheric heating and surface cooling introduced by these aerosols have been demonstrated to be able to interact with dynamical processes in various scales to alter atmospheric circulation, and hence clouds and precipitation. Recent studies have suggested that the changes in precipitation …