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<p>Amid accelerating global warming, Pakistan faces severe climate risks, with shifting temperature and precipitation patterns threatening ecosystems, livelihoods, and water security. This study develops a comprehensive, performance‐driven framework to evaluate and project hydroclimatic changes across Pakistan using 22 CMIP6 Global Climate Models (GCMs) under three Shared Socioeconomic Pathways (SSP1–2.6, SSP2–4.5, SSP5–8.5) for early (2021–2060) and late (2061–2100) 21st-century periods. Model evaluation against the ERA5 reanalysis used the Symmetrical Uncertainty (SU) metric and identified ACCESS-ESM1-5, INM-CM5-0, and MPI-ESM1-2-LR as the top performers. Three statistical downscaling and bias-correction techniques—LARS-WG, Quantile Mapping (QM), and SDSM—were tested, with QM performing best for temperature (KGE ≈0.86–0.90, r ≈ 0.9) and LARS-WG for precipitation (KGE ≈ 0.04). Bias-corrected outputs from the best models were aggregated using four ensemble techniques (Arithmetic Mean, Median, Bayesian Model Averaging, Independence-Weighted Mean), achieving high agreement with ERA5 (r &gt; 0.97, RMSE &lt; 2&#xa0;°C for temperature). Projections reveal robust, spatially coherent warming across all regions. Annual mean temperature (Bio-1) rises by 1.2–1.5&#xa0;°C in SSP1-2.6 early century and up to 4–5&#xa0;°C in SSP5-8.5 late century. Maximum (Bio-5) and minimum (Bio-6) temperatures increase by 5–6&#xa0;°C in the northern highlands (Gilgit-Baltistan, Khyber Pakhtunkhwa, Baluchistan), while the annual temperature range (Bio-7) contracts by 3–4&#xa0;°C in the southern plains. Seasonal indices (Bio-8–Bio-11) indicate warming exceeding 6&#xa0;°C in the wettest and warmest quarters. Precipitation indicators show intensified monsoonal activity, with annual rainfall (Bio-12) and wettest-month precipitation (Bio-13) increasing by up to 300&#xa0;mm, particularly in Azad Kashmir and Punjab. Conversely, arid provinces—Sindh and southwestern Baluchistan—exhibit limited rainfall change but strong thermal amplification (&gt; 4&#xa0;°C). These findings highlight Pakistan’s dual trajectory of thermal amplification and hydroclimatic intensification, identifying northern regions as hot-wet risk zones and southern provinces as hot-dry stress zones—providing a robust, high-resolution foundation for targeted climate adaptation planning.</p>

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Projected bioclimatic shifts in Pakistan: A CMIP6 ensemble analysis under shared socioeconomic pathways

  • 期刊论文

  • 发表日期：

    2026年1月6日

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  • Wisal Khan,
  • Mohamad Hidayat bin Jamal,
  • Mohd Khairul Idlan Muhammad,
  • Najeebullah Khan,
  • Shamsuddin Shahid

摘要

Amid accelerating global warming, Pakistan faces severe climate risks, with shifting temperature and precipitation patterns threatening ecosystems, livelihoods, and water security. This study develops a comprehensive, performance‐driven framework to evaluate and project hydroclimatic changes across Pakistan using 22 CMIP6 Global Climate Models (GCMs) under three Shared Socioeconomic Pathways (SSP1–2.6, SSP2–4.5, SSP5–8.5) for early (2021–2060) and late (2061–2100) 21st-century periods. Model evaluation against the ERA5 reanalysis used the Symmetrical Uncertainty (SU) metric and identified ACCESS-ESM1-5, INM-CM5-0, and MPI-ESM1-2-LR as the top performers. Three statistical downscaling and bias-correction techniques—LARS-WG, Quantile Mapping (QM), and SDSM—were tested, with QM performing best for temperature (KGE ≈0.86–0.90, r ≈ 0.9) and LARS-WG for precipitation (KGE ≈ 0.04). Bias-corrected outputs from the best models were aggregated using four ensemble techniques (Arithmetic Mean, Median, Bayesian Model Averaging, Independence-Weighted Mean), achieving high agreement with ERA5 (r > 0.97, RMSE < 2 °C for temperature). Projections reveal robust, spatially coherent warming across all regions. Annual mean temperature (Bio-1) rises by 1.2–1.5 °C in SSP1-2.6 early century and up to 4–5 °C in SSP5-8.5 late century. Maximum (Bio-5) and minimum (Bio-6) temperatures increase by 5–6 °C in the northern highlands (Gilgit-Baltistan, Khyber Pakhtunkhwa, Baluchistan), while the annual temperature range (Bio-7) contracts by 3–4 °C in the southern plains. Seasonal indices (Bio-8–Bio-11) indicate warming exceeding 6 °C in the wettest and warmest quarters. Precipitation indicators show intensified monsoonal activity, with annual rainfall (Bio-12) and wettest-month precipitation (Bio-13) increasing by up to 300 mm, particularly in Azad Kashmir and Punjab. Conversely, arid provinces—Sindh and southwestern Baluchistan—exhibit limited rainfall change but strong thermal amplification (> 4 °C). These findings highlight Pakistan’s dual trajectory of thermal amplification and hydroclimatic intensification, identifying northern regions as hot-wet risk zones and southern provinces as hot-dry stress zones—providing a robust, high-resolution foundation for targeted climate adaptation planning.