Abstract:

Based on global climate models from Coupled Model Intercomparison Projection Phase 6 (CMIP6) under SSP1-1.9 scenario, the changes in mean temperature and precipitation, as well as seven extreme climate indices, over the 23 subregions at 1.5℃level (P1 phase) and cooled to 1.5℃ level (P2 phase) were projected. Results show that the differences of temperature, precipitation, and extreme climate events between P1 and P2 phases show good agreement worldwide among multiple models, with obvious regional and local features. Multi-model consistent changes in temperature extremes generally approach or exceed 15% of the global land area. The spatial pattern of extreme cold events differences between two phases is similar to that of winter mean temperature, and the distribution of extreme hot events shows the local character. Globally, the areas with multi-model consistent increases in both cold and hot events are larger than those with the decreases. The risk of extreme cold/hot events will increase over the western part of mid-high latitudes in Eurasia, North America and northeastern China/the Tibet Plateau, eastern China, South Asia, East Africa, North America and Antarctic. Multi-model consistent changes in precipitation extremes generally exceeds 20% of global land area, but the area with increases is close to that with decreases. The spatial pattern of heavy precipitation differences is partially similar to that of annual mean precipitation: the values over southern China, South Asia, Southeast Asia, eastern and southwestern South America, North America, Australia, and central and eastern Europe will increase with good agreement, and the values over North China to northeastern China, southern edge of the Tibet Plateau, southern Africa, northern South America and northern Australia will decrease with good agreement. More consecutive dry days (CDDs) are projected in most regions, the large changes with good agreement can be found over Central Asia, South Asia, the Tibet Plateau, central and northern Russia, north of Sahara in Africa and central Africa, central Australia, parts of Antarctic. It indicates that even if global carbon emission peaks before 2030 and then begins to reduce immediately, temperature and precipitation extremes at certain regions will be even larger than those before overshooting, due to the diverse regional climate responses to global warming. Then the impact will still last many years, with the influence increasing. Thus, the projected increases in extreme climate events on regional and local scale should be alerted.

Key words: 1.5℃ warming level, Overshoot, Extreme climate, Climate projection