A revival of Indian summer monsoon rainfall since 2002

Abstract

A significant reduction in summer monsoon rainfall has been observed in northern central India during the second half of the twentieth century, threatening water security and causing widespread socio-economic impacts. Here, using various observational data sets, we show that monsoon rainfall has increased in India at 1.34 mm d−1 decade−1 since 2002. This apparent revival of summer monsoon precipitation is closely associated with a favourable land–ocean temperature gradient, driven by a strong warming signature over the Indian subcontinent and slower rates of warming over the Indian Ocean. The continental Indian warming is attributed to a reduction of low cloud due to decreased ocean evaporation in the Arabian Sea, and thus decreased moisture transport to India. Global climate models fail to capture the observed rainfall revival and corresponding trends of the land–ocean temperature gradient, with implications for future projections of the Indian monsoon. Since ∼1950, a significant reduction in Indian monsoon rainfall has been observed. Here, it is shown that land–ocean temperature contrasts have produced more favourable monsoon conditions since 2002, reviving summer monsoon rainfall over India.