Author: ["Subimal Ghosh","Debasish Das","Shih-Chieh Kao","Auroop R. Ganguly"]
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Abstract
Future changes in the Indian monsoon could affect millions of people, yet even the ways in which it might have changed over recent years remain uncertain. Statistical analysis indicates that during the second half of the twentieth century there were no spatially uniform changes in the frequency or intensity of heavy rainfall events over India, but there was an increase in the spatial variability of these characteristics. Recent studies disagree on how rainfall extremes over India have changed in space and time over the past half century1,2,3,4, as well as on whether the changes observed are due to global warming5,6 or regional urbanization7. Although a uniform and consistent decrease in moderate rainfall has been reported1,3, a lack of agreement about trends in heavy rainfall may be due in part to differences in the characterization and spatial averaging of extremes. Here we use extreme value theory8,9,10,11,12,13,14,15 to examine trends in Indian rainfall over the past half century in the context of long-term, low-frequency variability. We show that when generalized extreme value theory8,16,17,18 is applied to annual maximum rainfall over India, no statistically significant spatially uniform trends are observed, in agreement with previous studies using different approaches2,3,4. Furthermore, our space–time regression analysis of the return levels points to increasing spatial variability of rainfall extremes over India. Our findings highlight the need for systematic examination of global versus regional drivers of trends in Indian rainfall extremes, and may help to inform flood hazard preparedness and water resource management in the region.Cite this article
Ghosh, S., Das, D., Kao, SC. et al. Lack of uniform trends but increasing spatial variability in observed Indian rainfall extremes. Nature Clim Change 2, 86–91 (2012). https://doi.org/10.1038/nclimate1327 