The South Asian summer monsoon directly affects the lives of more than 1/6th of the world’s population. There is substantial variability within the monsoon season, including fluctuations between periods of heavy rainfall (wet spells) and low rainfall (dry spells)1. These fluctuations can cause extreme wet and dry regional conditions that adversely impact agricultural yields, water resources, infrastructure and human systems2, 3. Through a comprehensive statistical analysis of precipitation observations (1951–2011), we show that statistically significant decreases in peak-season precipitation over the core-monsoon region have co-occurred with statistically significant increases in daily-scale precipitation variability. Further, we find statistically significant increases in the frequency of dry spells and intensity of wet spells, and statistically significant decreases in the intensity of dry spells. These changes in extreme wet and dry spell characteristics are supported by increases in convective available potential energy and low-level moisture convergence, along with changes to the large-scale circulation aloft in the atmosphere. The observed changes in wet and dry extremes during the monsoon season are relevant for managing climate-related risks, with particular relevance for water resources, agriculture, disaster preparedness and infrastructure planning.
At a glance
- Active/break cycles: Diagnosis of the intraseasonal variability of the Asian Summer Monsoon. Clim. Dynam. 18, 85–102 (2001). &
- 2006). & in The Asian Monsoon (ed Wang, B.) Ch. 18, (Springer/Praxis Publishing,
- Climate change and the South Asian summer monsoon. Nature Clim. Change 2, 587–595 (2012). &
- 2011). & in Climate Change and Food Security in South Asia (ed Lal, R.et al.) Ch. 2, (Springer Science+Business Media,
- Floods in Mumbai: Impact of public health service by hospital staff and medical students. J. Postgrad Med. 52, 312–324 (2006). , &
- Simulated changes in active/break spells during the Indian summer monsoon due to enhanced CO2 concentrations: Assessment from selected coupled atmosphere–ocean global climate models. Int. J. Climatol. 27, 837–859 (2007). , , , &
- Active and break spells of the Indian summer monsoon. J. Earth Syst. Sci. 119, 229–247 (2010). , &
- Intraseasonal and seasonally persisting patterns of Indian monsoon rainfall. J. Clim. 20, 3–20 (2007). &
- Characteristics of monsoon breaks and intraseasonal oscillations over central India during the last half century. Atmos. Res. 128, 120–128 (2013).
- Increasing trend of extreme rain events over India in a warming environment. Science 314, 1442–1445 (2006). , , , &
- Anthropogenic aerosols and the weakening of the South Asian summer monsoon. Science 334, 502–505 (2011). , &
- Northern Hemisphere summer monsoon intensified by mega-El Niño/Southern Oscillation and Atlantic Multidecadal Oscillation. Proc. Natl Acad. Sci. USA 110, 5347–5352 (2013). et al.
- Atmospheric brown clouds: Impacts on South Asian climate and hydrological cycle. Proc. Natl Acad. Sci. USA 102, 5326–5333 (2005). et al.
- Risk management and climate change. Nature Clim. Change 3, 447–450 (2013). et al.
- IPCC, Summary for Policymakers in Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) (Cambridge Univ. Press, 2013)
- Some evidence of climate change in twentieth-century India. Climatic Change 85, 299–321 (2007). , , &
- Higher hydroclimatic intensity with global warming. J. Clim. 24, 5309–5324 (2011). et al.
- Changes in the characteristics of rain events in India. J. Geophys. Res. 114, D10109 (2009). , , &
- Increasing trend of synoptic activity and its relationship with extreme rain events over Central India. J. Clim. 23, 1004–1013 (2010). , &
- Changes in tropical cyclone number, duration, and intensity in a warming environment. Science 309, 1844–1846 (2005). , , &
- Dynamics of breaks in the Indian summer monsoon. J. Atmos. Sci. 57, 1354–1372 (2000). , &
- An evaluation of climatological data in the Indian ocean area. J. Meteorol. Soc. Jpn 72, 359–386 (1994).
- Lack of uniform trends but increasing spatial variability in observed Indian rainfall extremes. Nature Clim. Change 2, 86–91 (2012). , , &
- Absorbing aerosols facilitate transition of Indian monsoon breaks to active spells. Clim. Dynam. 37, 2181–2198 (2011). , , &
- Subseasonal extremes of precipitation and active-break cycles of the Indian summer monsoon in a climate-change scenario. Quart. J. R. Meteorol. Soc. 135, 549–567 (2009). &
- 2006). Monsoon Weather Variation and its Impact on Agriculture (Department of Information and Cultural Affairs,
- Dwindling groundwater resources in northern India, from satellite gravity observations. Geophy. Res. Lett. 36, L18401 (2009). , &
- 2009). & Adaptation of Small Scale Farmers to Climatic Risks in India (Sustainet India,
- APHRODITE: Constructing a long-term daily gridded precipitation dataset for Asia based on a dense network of rain gauges. Bull. Am. Meteorol. Soc. 93, 1401–1415 (2012). et al.
- Monsoons: Processes, predictability, and the prospects for prediction. J. Geophys. Res. 103, 14451–14510 (1998). et al.