Understanding of the Roles of Global Warming and Natural Variability on Monsoon Rainfall

Climate studies predict changes in global precipitation in response to increase in the mean global surface temperature of the Earth. A prevailing theory of precipitation change in a warming world is that wet areas will get wetter. Under the global warming scenario in the Coupled Model Intercomparison projects, many studies have shown that future global monsoon rainfall will be increased by the atmospheric moistening. However, on a basin scale, this is not always the case. Moreover, understanding the relative effects of global warming and natural variability in different monsoon regions is lacked despite many studies on climate change. Understanding the effects of global warming and natural variability on temporal trends in precipitation in monsoon regions is thus a crutial step in improving the modelling and forecasting of monsoon behavior. The main points in this talk are, therefore, to identify long-term climatic variability by analyzing changes in average monsoon precipitation from 1958-2015, specipically focusing on different regional monsoons, and to elucidate the roles of global warming and natural variability in driving these precipitation changes. The result shows that while changes in global precipitation are driven by the combined effects of global warming and natural variability, the monsoon precipitation in various regions of the world occurs through a different forcing.