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Abstract Borneo Vortices (BVs) are weather systems that are responsible for devastating hydro-climatic extremes and significant losses of life and property in Southeast Asia. The typical resolution of most current climate models is insufficient to resolve these high-impact, synoptic-scale weather systems. Here, an ensemble of high-resolution models projects that future BVs may become less frequent and more stationary, driven by the weakening of the Northeast monsoon flow and associated cold surges across North Borneo. However, substantial increases in both the intensity and the total amount of precipitation from BVs are projected. Such changes are driven by the more humid and convectively unstable lower troposphere. As a result, the contribution of BVs to the accumulation of both total precipitation and extreme precipitation is projected to increase considerably in the vicinity of the southern South China Sea, making individual BVs more threatening to the adjacent coastal regions.

Abstract Extra-tropical continental summer heatwaves often occur under persistent anticyclones or blocking. Here we partition heatwave changes into contributions from blocking changes, heatwave–blocking relation change and mean temperature increase, under global warming in climate models. We employ an optimized blocking index that best correlates with heatwaves (Pearson correlation of 0.7) and find heatwave-driving blocking decreases but the change in heatwave–blocking relation likely dominates. Over Europe, with a historical heatwave frequency of 2.5%, less blocking will cause 0.6% fewer heatwaves, steepened heatwave–blocking relation will cause 1.4% more heatwaves, and the mean temperature increase will cause 60% more heatwaves. Over Greenland, flattened heatwave–blocking relation will dominate over the insignificant decrease in blocking. The future increase in heatwave frequency is not caused by changes in blocking frequency, but by factors such as thermodynamics, that enhance the capacity of blocking to drive heatwaves.