Twenty‐seven CMIP6 models were grouped into three ensembles based on the simulated performance of heatwaves in North China during present‐day (1995–2014), and future changes in the duration and intensity of heatwaves were projected under SSP1‐2.6, SSP2‐4.5 and SSP5‐8.5. The selected three ensembles showed consistent projections: both the duration and intensity of heatwaves would increase significantly, with the greatest under SSP5‐8.5. Besides, the heatwave growth in 2081–2100 would double in 2041–2060, except for SSP1‐2.6, where heatwaves would be similar in both periods. For the spatial distribution, the duration (intensity) would increase more in southern (western) parts of North China. Combining heatwaves with population and GDP, future heat exposures would concentrate on urban areas and the tertiary industry. For example, the 2041–2060 population exposure would reach 3.2–5.6 times the current level, with contributions from the urban population ranging from 55% to 60%. The GDP exposure would hit tens to hundreds of times the current level, with the tertiary sector replacing the secondary sector as the leading industry in North China, producing the major contribution and facing significant heat‐related risks. Overall, there will be significant heat‐related impacts under SSP5‐8.5, about 1.5–3.0 fold of those under SSP1‐2.6 and SSP2‐4.5. The urban and tertiary sectors would suffer greater risks relative to the rural and other industries. Our results reinforced the need to minimize global emissions and develop strategic plans to mitigate heat impacts under high‐emission scenarios, especially for urban areas and the tertiary industry, requiring great attention to climate adaptation.

Based on bias-corrected future projections from the Providing REgional Climates for Impacts Studies (PRECIS) regional climate model under both RCP4.5 and 8.5 scenarios over China, extreme climatic events at the middle and end of the twenty-first century are investigated in this paper. The model performance of PRECIS is validated using comparisons with observations and HadGEM2-ES projections, and the bias correction adds fidelity to the projections of basic climate variables and extreme climate events. In the future, our single-realisation estimates show that the number of frost days is projected to decrease and days with tropical nights are projected to increase. Including northeast China, Sichuan Basin, middle and lower reaches of Yangtze River and south China, the number of consecutive dry days will increase from our single-realisation estimates, which will exhibit a spatial distribution almost similar to that of consecutive wet days in the coming decades. Although precipitation indices associated with duration will increase, a simple precipitation index depicting the intensity of extreme events will decrease over east and south China in the future from our single-realisation projections. Daily rainfall above 50 mm, which is usually regarded as a rainstorm event, is predicted to increase under the RCP4.5 scenario over most of China from our single-realisation estimates; while the same change pattern will occur in southernmost China, similarly spatially distributed for the RCP8.5 scenario, the number of rainstorm will first increase in the middle of the twenty-first century and then slow at the end of the twenty-first century in the Yangtze River region. In conclusion, our single-realisation estimates indicate that the persistence of extreme precipitation will increase with time, but the change of extreme precipitation intensity is not significant in the future. The comparison of climatic extreme events under the RCP4.5 scenario with those under the RCP8.5 scenario shows that extreme climate events will be enhanced under the higher emissions scenario; hence, reductions in greenhouse gas emissions will help alleviate climate change effects in the future.

ABSTRACT:The Himalaya holds the world record in terms of range and elevation. It is one of the most extensively glacierized regions in the world except the Polar Regions. The Himalaya is a region sensitive to climate change. Changes in the glacial regime are indicators of global climate changes. Since the second half of the last century, most Himalayan glaciers have melted due to climate change. These changes directly affected the changes of glacial lakes in the Himalayan region due to the glacier retreat. New glacial lakes are formed, and a number of them have expanded in the Everest region of the Himalayas. This paper focuses on the two glacial lakes which are Imja Lake, located at the southern slope, and Rongbuk Lake, located at the northern slope in the Mt. Everest region, Himalaya to present the spatio-temporal changes from 1976 to 2008. Topographical conditions between two lakes were different (Kruskal-Wallis test, p < 0.05). Rongbuk Lake was located at 623 m higher than Imja Lake, and radiation of Rongbuk Lake was higher than the Imja Lake. Although size of Imja Lake was larger than the Rongbuk Lake in 2008, the growth speed of Rongbuk Lake was accelerating since 2000 and exceeds Imja Lake in 2000-2008. This trend of expansion of Rongbuk Lake is anticipated to be continued in the 21st century. Rongbuk Lake would be the biggest potential risk of glacial lake outburst flood (GLOF) at the Everest region of Himalaya in the future.

Recent studies suggest Asian Water Tower (AWT) is vulnerable to climate change with a detrimental effect on water and food security. Comprehensive information about the spatio-temporal variability of lakes, an important freshwater resource, is lacking. Therefore, we analyzed 89,480 Landsat images to examine the change in the lakes size around AWT between 1977±2 and 2020±2. Sequentially, the trends of precipitation, snow water equivalent, glacier mass, and permafrost were analyzed to understand what caused the lake's alteration. According to our findings, from 1977±2 to 2020±2, 84% of mapped lakes grew during the wet season, whereas 81% of the lakes grew during the dry season. Lakes in the Inner TP and Tarim Interior basins expanded dramatically. The Helmand, Amu Darya, and Yangtze basins are the primary locations of shrinking lakes. The Aral Sea shrunk by 90%. From the region as a whole, the alpine lakes showed a shrinking trend and the plain lakes showed an expanding trend from 1977±2 to 1990±2, and vice versa from 1990±2 to 2020±2. Glacial loss and permafrost thawing were corresponding to lake expansion in the Inner TP, Tarim Interior, Syr Darya, and Mekong basins. Permafrost discontinuities may cause Indus and Ganges to not grow significantly in lakes with increased recharge to the basin. Extreme droughts depleted the lake in Helmand. Human intervention have caused the shrinking of the Aral Sea and the lakes in the lower Yangtze River. As AWT retreats and feeds lakes, we need to take immediate action for managing risks and adaption.