Regional changes in extreme temperature records over Pakistan and their relation to Pacific variability

Abstract

The widespread changes in extreme temperatures record are of significant importance for climate risk management. Trends and variability of extreme temperature events in the agro-ecological zones of Pakistan are not fully understood, despite their importance. This study investigates the annual and seasonal trends of temperature extremes, and the role of Pacific variability during 1980–2019. The homogeneity of 40 synoptic stations, spatially distributed over Pakistan was assessed by removing non-climatic shifts from the data. There is distinct increases (decreases) in the upper (lower) tails are noticed in a spatially aggregated perspective. The strongest warming trends of 0.35 (0.49) ∘C decade−1 for the hottest nights (days) occur during spring, which is the hottest season of the year. The significant warming (hotter) trends are apparent for the agro-ecological zones located to central, western, and southeastern-Pakistan. The principal component analysis showed a robust increase in the intensity and frequency of extreme temperatures, with a total variance of 94.7%. In the spring season, we found strong connections between La Niña (El Niño) events over the western Pacific Ocean and changes in extreme temperatures. Analysis reveals that the strength of La Niña episodes has a much larger influence on the intensity of extremely high-temperature events over arid to semi-arid climatic zones. This information is of great use for the seasonal prediction of extremely hot days in the region and will help policymakers to formulate climate change adaptation plans.