On the present and future changes in heat waves over India in coupled climate models

It is evident that climate is changing however, there have been not many regional scale systematic efforts to quantify the climate extremes (e.g., heatwave) under various emission scenarios. South Asia has a population of over 1.4 billion, with most of this population located in India and is vulnerable to future changes in high temperature conditions e.g., heat waves and its duration. Here, we use 13 state-of-the-art coupled climate models from CMIP6 experiments along with their ensembles to estimate their fidelity and associated uncertainties in predicting heat waves over the Indian temperature homogenous regions that have resulted from human-induced warming, during the period 1984–2014. We applied various skill metrices for model performance evaluation and found that ensemble of all the 13 CMIP6 models is close to the observation whereas individual model performance varied geographically. This is because individual models have their own interannual variability which affects the overall performance. Further we computed the temperature changes for near future (2030-2060) and far future (2070-2100) at 95% significance level using SSP1, 2 and 5. The maximum temperature during the northern hemisphere summer is projected to increase by 1.3°C, 2.1°C and 3.7°C for SSP1, SSP2 and SSP5 respectively. The frequency of heat waves is also projected to increase, with the most affected areas showing 3+ more heat waves per summer season when compared to historical values. The Indo-Gangetic plain is found in the most affected regions, where weeklong heat wave duration is expected at higher emission scenario affecting larger portion of. population (~ 40% of India’s population). Our findings support the urgent need for more ambitious mitigation and adaptation strategies to minimize the public health impacts of climate change.

Keywords: Climate change, Extremes, CMIP6