Conspicuous temperature extremes over Southeast Asia: seasonal variations under 1.5 °C and 2 °C global warming

Guided by the Paris Agreement, the IPCC Special Report on Global Warming of 1.5 degrees C reported potential risks of climate change at different global warming levels (GWLs). To provide fundamental information on future temperature extremes over Southeast Asia (SEA), projected changes in temperature extreme indices are evaluated for different seasons at 1.5 degrees C and 2 degrees C GWLs against the historical reference period of 1976-2005 based on the ensemble of CORDEX simulations. Results show that the temperature indices increase significantly across the Indochina Peninsula and Maritime Continent at both GWLs except for decreasing daily temperature range (DTR) in the dry season, with more pronounced magnitudes at 2 degrees C GWL. Moreover, the regionally averaged ensemble medians of the indices show various changes over different subregions. At 1.5 degrees C and 2 degrees C GWLs, most pronounced increases of threshold indices. i.e. summer days (SU) and tropical nights (TR), are projected in Sumatra and Sulawesi for both wet and dry seasons. The warm spell duration (WSDI) increases generally, with strongest magnitudes for Sumatra and Sulawesi (Philippines and Sulawesi) in the wet (dry) season. On the other hand, significant increases of warm days and nights can also be observed at 2 degrees C GWL compared to 1.5 degrees C, particularly in the dry season, suggesting the high sensitivity of temperature extremes over the SEA. The projected potentially conspicuous temperature extremes under global warming of 1.5 degrees C and 2 degrees C primarily concentrate on the densely populated coastal regions of the main islands, showing the necessity of restricting global warming to 1.5 degrees C aiming at the eradication and reduction of regional climate stress for the human system in the developing countries over the SEA.