Climate change and spatio-temporal trend analysis of climate extremes in the homogeneous climatic zones of Pakistan during 1962-2019

extremes. As the climate and extremes conditions are not the uniform in all climate zone, therefore, it is suggested to the formers and agriculture department to harvest crops resilient to the climatic condition of each zone. Temperature has increasing trend in the northern Pakistan, therefore, the concerned stakeholders need to make rational plans for higher river flow/flood situation due to snow and glacier melt. 1. Introduction Climate change has been attributed to human-caused activities, especially increased green- house gases emissions after the mid-twentieth century [1–4]. Climate change is causing a num- ber of threats, including an increase in the frequency of extreme events and other disasters [5,6]. Evidence of observed changes in extremes such as heavy precipitation, heatwaves, tropi- cal cyclones, and droughts, and, in particular, the attribution of these extremes to human influ- ence, has strengthened since AR5 (Fifth Assessment Report) [6]. The societal infrastructure is becoming more vulnerable to climate extremes, which are exacerbated by climate change [7– 9]. Climate extremes such as droughts, floods, heatwaves, and typhoons have geographically different economic, health, social, ecological, and environmental impacts [10–15]. Many approaches have been developed to explore variability and trends of climate extremes using observed precipitation and temperature data around the world. For example, Grima et al. [16] investigated the variability of temperature and precipitation in the Upper Huai River

Basin of China using yearly time series data from 1960 to 2016, concluded a decreasing trend in precipitation and a considerably increasing trend in temperature at all meteorological sta- tions. Bougara et al. [17] investigated the variability of rainfall in the Tafna basin in northeast- ern Algeria using observed data from 1979 to 2011, resulted in heterogeneous results in different stations. Asfaw et al. [18] performed variability and trend analyses of temperature using data from 1901 to 2014 in the Woleka sub-basin in northcentral Ethiopia and found a significant increasing trend in mean and minimum average temperatures. Other studies that are based on observe station data on variability and trend analysis of temperature and precipi- tation in various regions of the globe include: [19–24]. Most of the studies conducted in Pakistan considered a sub-region of Pakistan for their analyses [25–29]. For instance, Alam et al. [25] considered three meteorological stations in the north-western part (Khyber Pakhtoonkhwa province) and used Mann Kendall (MK) test for trend analysis using daily observed data for the duration of 1960–2020. Safdar et al. [27] inves- tigated the climate change indicators and spatio-temporal shift in Monsoon pattern by using observed data for the duration of 1980–2017. They concluded a warming tendency and a decrease in the rainfall in the Monsoon region of Pakistan. Hussain et al. [26] investigated vari- ability and trends in precipitation and temperature over the northern part of Pakistan by using

observed meteorological data (duration of 1955–2016 for some station and 1995–2012 for other stations). They concluded elevation-dependent conclusions in the target location, for instance, they noted increasing trend in maximum temperature and precipitation at station with elevation 1500–2800 meters in contrast to elevation less than 1500 meters during 1955– 2016. Further studies which investigated variability and trends analysis in the sub-regions of the country include [28–30]. Studies related to precipitation and temperatures’ extremes in different parts of the world revealed that these extremes are increased in terms of frequency, intensity and persistence [31– 33]. The study of Sun et al. [33] concluded that the extreme precipitation has increased at two- PLOS ONE Climate change and extremes analysis using observed data (1962-2019) over Pakistan PLOS ONE | https://doi.org/10.1371/journal.pone.0271626 July 27, 2022 2 / 27 Competing interests: The authors have declared that no competing interests exist.