Assessment of the impacts of climate change on the construction of homogeneous climatic regions and ensemble climate projections using CMIP6 data over Pakistan

In the 21st century, the global environment faces significant threats due to climate change, ranging from floods and droughts to heat waves and other extreme weather events. In recent decades, Pakistan has experienced severe flooding and prolonged droughts, compounding challenges related to livelihoods, public health, and population displacement. The availability of precise and robust climate change information is paramount in addressing and mitigating the adverse impacts on a region's environment and its communities. The present study intends to assess the effects of climate change on the development of homogenous climate regions (HCRs) and then developed ensemble climate projections under the shared socioeconomic pathways (SSPs) using CMIP6 data. In the first step, HCRs were developed by integrating the cluster analysis approach and L-moment technique, identifying five distinct climatic regions. HCRs were developed using both observed data and ensemble baseline data which allowed us to thoroughly evaluate the ensemble data's performance. Subsequently, we extended our analysis to the future period (2015–2044) using ensemble climate data according to SSP2–4.5 and SSP5–8.5. Our findings indicate that, under both SSPs, certain stations exhibit discordant climatic trends in the future due to climate change. Ensemble climate projections were developed over each region for both SSPs for the duration of 2015–2044. A significant increase of 2–3.20 °C has been noted in the summer season in zone 3 and zone 5 (a region that has one of the world's largest glaciers) in maximum as well as minimum temperatures. Temperature has upward trend in the other region as well while precipitation has a mixed trend in all regions. The insights gleaned from this study hold significance and offer valuable guidance for decision-makers involved in water management, agricultural planning, and disaster management.