Updated insights on climate change-driven temperature variability across historical and future periods

This study highlights the benefits of using high-resolution reanalysis and climate models to assess climate change over time at the subcontinental scale for both present and future periods. The emergence of climate change over the internal variability for each AR6 region is studied by evaluating the decadal frequency distributions of the monthly normalized 2 m temperature anomalies for the 1951-2020 historical and 2015-2100 future periods. To achieve this, monthly averaged daily temperature data from ERA5 and an ensemble of 22 CMIP6 GCMs, following a range of future climate scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5), are used. The ERA5 results show a decadal shift in the mean temperature anomalies between 0.6-2.6 $$\sigma$$ in DJF and 1.1-2.6 $$\sigma$$ in JJA during the 1951-1980 period. The CMIP6 GCM ensemble can reproduce this historical warming on a climatological timescale, with a large agreement for all regions. Moreover, climate projections strongly suggest that this warming will continue under all climate change scenarios and will be more pronounced by the end of the century. The two most likely scenarios (SSP2-4.5 and SSP3-7.0) show significant evidence that extremely hot temperatures (anomalies of more than three standard deviations (3 $$\sigma$$ ) warmer than the climatology of the 1951-1980 base period) will become the normal climate in Africa and South America for the 2071-2100 period. It is seen that the regional mean temperature anomalies will increase in weak, moderate, and strong forcing scenarios, reaching climatic extremes with expected major implications for the water cycle, agriculture, ecosystems, society, and human health.