A seven-fold rise in the probability of exceeding the observed hottest summer in India in a 2 °C warmer world

Abstract

Heatwaves and extreme temperatures during summer (April-May) in India have profound implications on public health, mortality, water availability, and productivity of labourers. However, how the frequency of the hottest summers in observed record will change under the warming climate in India is not well explored. Using observations from the India Meteorological Department, we show that mean maximum summer temperature has increased significantly in three (arid, monsoon, and savannah) out of five major climatic regions of India during 1951-2015. We identify the hottest summer in the observed record in the five climatic regions in India. The arid, cold, and temperate regions experienced the hottest summer in 2010 while monsoon and Savannah regions witnessed the hottest summer in 1979 and 1973, respectively. Based on simulations from the Climate of 20th Century Plus (C20C+) Detection and Attribution project, we show that the regional hottest summer of 2010 can be attributed to the anthropogenic warming. We then use simulations of a large (2000 year) ensemble of the EC-Earth model to estimate the exceedance probability of the observed hottest summer in the present climate, 2°C and 3°C warming worlds in India. The exceedance probability of the observed hottest summers shows a rise of more than seven and twenty-fold in the 2°C and 3°C warming world, respectively, compared to the present climate. The projected increases in the frequency of the hot summers and associated heatwave days will pose great societal challenges in the future in India.

Increasing Heat‐Stress Inequality in a Warming Climate

“…Extreme heat is among the deadliest and costliest of natural hazards globally, claiming more than 166,000 lives between 1998 and 2017 (Lesk et al., 2016; Mazdiyasni et al., 2017; Mizutori & Guha‐Sapir, 2017), one‐third of which can directly be attributed to anthropogenic climate change (Vicedo‐Cabrera et al., 2021). Heatwaves, defined as prolonged periods of excessive heat, are becoming more intense, more frequent and longer across many regions of the globe (Nanditha et al., 2020; Perkins et al., 2012) and are expected to further intensify in a warming climate (Li, 2020). Exposure to extreme heat events is also increasing around the world (Batibeniz et al., 2020; Mukherjee et al., 2021; Russo et al., 2015), currently exposing ∼30% of the global population to health‐threatening heat (Mora et al., 2017) with a substantial projected increase by the end of the century (King & Harrington, 2018; Li et al., 2020; Mishra et al., 2017).…”

Relative Contribution of Precipitation and Air Temperature on Dry Season Drying in India, 1951–2018

“…Anthropogenic warming has significantly altered the hydrologic cycle, which is projected to intensify in the future (Allen & Ingram, 2002;Wu et al, 2013). The noticeable impacts of climate warming have been witnessed on drought (AghaKouchak et al, 2014;Chen & Sun, 2017;Diffenbaugh et al, 2015;Williams et al, 2015), heat waves (JA et al, 2020;Mishra et al, 2017;Sippel et al, 2016;Stott et al, 2004;Sun et al, 2017), floods (Ali et al, 2019;Dottori et al, 2018;Pall et al, 2011), and soil moisture (Lorenz et al, 2010;Seneviratne et al, 2010Seneviratne et al, , 2013 across the globe. Soil moisture plays an essential role in the partitioning of water and energy budget (Trenberth et al, 2014).…”

A climate database with varying drought‐heat signatures for climate impact modelling

“…The climate forcing was generated with EC-Earth, a fully coupled global climate model (Hazeleger et al, 2012). The 2,000-year climate dataset and its companions with +2°C and +3°C global climate change has already been used to identify drivers of crop failure (Vogel et al, 2021), study extreme river discharge in a warmer world (Van der Wiel et al, 2019c), evaluate extremes in the renewable energy sector (Van der Wiel et al, 2019a, 2019b, assess changes in heatwaves in India (Nanditha et al, 2020) and detect changes in mountain-specific climate indicators in a warmer world in High Mountain Asia (Bonekamp et al, 2020), highlighting its applicability for assessing climate impacts.…”