Change in high-temperature intensity-duration-frequency under different warming scenarios over India

Abstract

This study examined the hottest temperature events in each year for a period of 1 to 10 consecutive days across India under 1.5 °C, 2 °C, and 3 °C global warming levels (GWLs) and two periods (T1: 2021–2050, T2: 2071–2100) using the Coupled Model Intercomparison Phase 6 (CMIP6) framework. Bivariate copula analysis was applied to determine the joint probability distribution of the intensity and duration of high-temperature extremes across various GWLs. We also evaluated the change in return values for 10, 20, 50, and 100-year return periods over 2, 5, and 10-day durations. The intensity of the high-temperature extremes indicates a gradual rising trend across the country for durations ranging from 1 to 10 days for different GWLs. For the 2-day duration, the intensity of average temperature increases by 0.7–2.6 °C under all GWLs. The Western Himalaya region (2–4.3 °C) shows the highest increase in intensity of 2-day duration followed by the Northwest (0.93–2.51 °C) and Eastern Coastal (0.86–2.5 °C) regions under different GWLs. Whereas, the Interior Peninsula (0.56–2.15 °C) and Western coastal (0.56–1.9 °C) regions show a lower increase. Similar patterns were observed for 5- and 10-day duration. The 20-year return value of the intensity for a 2-day duration increases by 7–24% under all GWLs across India. The highest increase was observed in the Western Himalayas (23–48%) followed by the Northeast and Eastern Coastal (9–25%) regions under all GWLs. We have derived Temperature-Intensity-Duration-Frequency (TIDF) curves for eight selected urban agglomerations cities. Among them, Srinagar exhibits the highest increase in intensity (ranging from 19 to 32%) followed by Guwahati (9–16%) and Mumbai (5.5–12.8%). Whereas, Hyderabad exhibits the smallest increase in intensity (0.02%–8%). The duration of high-temperature extreme events increases for a given intensity and return period. It is also observed that for a given intensity and duration, the exceedance probability of high-temperature extremes increases under different GWLs. These insights are crucial for climate mitigation and adaptation strategies and can inform decisions by urban planners, policymakers, and communities in addressing the challenges posed by high-temperatures extreme.