By R Krishnan
The author is Programme Manager, Center for Climate Change Research, Indian Institute of Tropical Meteorology, Pune. firstname.lastname@example.org
The south Asian monsoon rains contribute to 75-80 per cent of the region’s annual precipitation. Thus the response of the monsoon hydrological cycle to global climate change becomes an issue of major concern.
The South Asian monsoon circulation sustains the lives of over one fifth of the world’s human population whose water supply is almost entirely dependent on the seasonal summer monsoon during June to September (Fig 1a). While on an average the seasonal monsoon rains contribute nearly 75–80 per cent of the annual precipitation in the region, their year-to-year variations have important implications. How the regional monsoon hydrological cycle might respond to global climate change thus becomes an issue of major concern. Researchers point out that greenhouse warming is likely to intensify the monsoon precipitation over South Asia due to increased atmospheric moisture content and enhanced surface and tropospheric warming. However, assessments of future changes remain ambiguous due to wide variations among the climate model projections. Historical records over India during the twentieth century indicate absence of any significant long-term trend in the summer monsoon rainfall for the country as a whole,...