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

are shown in Table 3. For zone 1, the mMK test for precipitation’s change shows significantly decreasing trend with value -0.0618. The values of mMK statistic for changes in maximum and minimum temperature are 0.0752 and 0.0762, respectively, indicating increasing trends. The mMK test’s results support the Karakoram anomaly during the 1962–1990 given in Table 5, however, the decadal analysis during the 1990–2019 offers complex results (discussed in detail under the Climate Change assessment and extremes’ analysis in HKH region). During the last decade, the trend analysis show that precipitation and temperature have decreasing and increasing trends, respectively, at the stations located in the Karakoram region. Results related to climates’ extremes are given in Figs 3 and 4 for all zones. Most of the tem- perature extremes are significantly increased during 1991–2019. The number of frost days decreased significantly while growing season length and summer days increased significantly in zone 1 (Northern Pakistan). Interestingly, TN10P shows a significantly decreasing trend in 1991–2019 while increasing trend in 1962–1990. TX10P and TX90P have significantly decreas- ing and increasing trends, respectively, during 1991–2019. Most of the precipitation extremes have increasing trends during 1962–1990 and decreasing trends during 1991–2019. For exam- ple, PRCPTOT, R10mm, R20mm and R25mm have significantly increasing and significantly decreasing trend during 1962–1990 and 1991–2019, respectively. R95P decreased but R99P

increased in zone 1. Spatial distribution of changes in selected temperatures’ extremes are pre- sented in Figs 5 and 6 while changes in selected precipitations’ extremes are mentioned in Fig 7 for all climate zones. The distribution of the number of CWD is displayed in Fig 8 for all zones. For zone 1, the average number of CWD increased from 16 to 19 in 1991–2019 compared to 1962–1990. A strong increase in variability is observed during 1991–2019. The maximum number of CDD is 60 and 40 during 1962–1990 and 1991–2019, respectively, given in Fig 9. The maximum num- ber of Frost days (FD0) has decreased from 110 to 88 during 1991–2019 compared to 1962– 1990 as shown in Fig 10. Zone 2. The results of t-statistic (Table 2) show a significant increase in average tempera- ture during MAM and JJA, increase during DJF, and insignificant decrease during SON. The mMK results for changes in maximum and minimum temperature indicate significantly increasing trend with values 0.0293 and 0.0938, respectively. On the other hand, average pre- cipitation increased significantly throughout in all seasons. The mMK tests’ results (Table 3) show a significantly decreasing trend in precipitation with a magnitude of -0.0141. Interestingly, this is the only region with the increasing number of frost days and decreasing GSL in both time slices. The SU25, TMAXMean, TN90p, TR20 and TX90p increased during the 1991–2019. The TMINMean increased significantly while TX10p and TN10p both decreased significantly during the 1991–2019. The CWD, WSDI, R10mm, R20mm and

R25mm decreased during the 1991–2019. The CSDI, PRCPTOT, R95p and R99p decreased during the 1991–2019. The RX1day (Max 1-day precipitation amount) and Rx5day (Max 5-day precipitation amount) increased significantly and decreased during the 1962–1990 and 1991–2019, respectively. The average number of CWD increased from 22 to 26 in the recent period. The standard deviation of CWD has increased from 8 (during 1962–1990) to 11 (during 1991–2019). The CDD (Fig 9) slightly reduced, with insignificant variability. The maximum number of FD0 recently increased from 34 to 47. Zone 3. The average temperature significantly increased in this region, except a significant decreased for JJA with a value of -0.42. In contrast, the average precipitation increased signifi- cantly throughout except an insignificant increase during the DJF. The results of mMK test show decreasing trends in precipitation change and minimum temperature change while an 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 9 / 27