Projected changes in high-temperature extremes across Indian urban agglomerations under different global warming levels: a bivariate approach.

Abstract

Climate extremes have risen in recent decades, and anthropogenic interventions are projected to continue driving climate change. This study assessed the annual maximum intensity of high-temperature extremes of 2, 5, and 10 consecutive days for 54 urban agglomerations under 1.5 °C, 2 °C, and 3 °C global warming levels (GWLs) using the Coupled Model Intercomparison Phase 6 (CMIP6) framework. We also assessed this relationship between duration and intensity of high-temperature extreme events by using bivariate copula functions. The average intensity of urban agglomerations increased by 3-8% across the different GWLs for 2-day duration. This trend continues for 5 and 10 days, highlighting the increasing risk of high-temperature extremes. The study found that urban high-temperature extremes rose significantly for 2, 5, and 10 days under various GWLs. Urban areas like Amritsar, Jalandhar, Delhi, Shimla, and Kanpur showed a higher increase in intensity of 20-26%, 22-28%, and 26-33% under 1.5 °C, 2 °C, and 3 °C GWLs, respectively. The return values (10, 20, 50, and 100 years) for a 2-day duration are projected to increase by 3.5-9% across most urban agglomerations under different GWLs. Amritsar, Jalandhar, Delhi, and Shimla experienced a significant increase in return values (10, 20, 50, and 100 years) for durations of 2, 5, and 10 days under different GWLs. By using temperature-intensity-duration-frequency (TIDF) curves, this study also highlights the interaction between duration and intensity for the selected eight urban agglomerations under various GWLs. This study highlights the urgent need for immediate climate change mitigation aligned with the national (Smart Cities Mission and AMRUT 2.0) and international (IPCC agreement and SGD11) goals that support urban planners, policymakers, and communities in managing the challenges posed by extreme temperatures.