Because of their dependence on water, natural and human systems are highly sensitive to changes in the hydrologic cycle. The authors introduce a new measure of hydroclimatic intensity (HY-INT), which integrates metrics of precipitation intensity and dry spell length, viewing the response of these two metrics to global warming as deeply interconnected. Using a suite of global and regional climate model experiments, it is found that increasing HY-INT is a consistent and ubiquitous signature of twenty-first-century, greenhouse gas–induced global warming. Depending on the region, the increase in HY-INT is due to an increase in precipitation intensity, dry spell length, or both. Late twentieth-century observations also exhibit dominant positive HY-INT trends, providing a hydroclimatic signature of late twentieth-century warming. The authors find that increasing HY-INT is physically consistent with the response of both precipitation intensity and dry spell length to global warming. Precipitation intensity increases because of increased atmospheric water holding capacity. However, increases in mean precipitation are tied to increases in surface evaporation rates, which are lower than for atmospheric moisture. This leads to a reduction in the number of wet days and an increase in dry spell length. This analysis identifies increasing hydroclimatic intensity as a robust integrated response to global warming, implying increasing risks for systems that are sensitive to wet and dry extremes and providing a potential target for detection and attribution of hydroclimatic changes.

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We used a high‐resolution nested climate modeling system to investigate the response of South Asian summer monsoon dynamics to anthropogenic increases in greenhouse gas concentrations. The simulated dynamical features of the summer monsoon compared well with reanalysis data and observations. Further, we found that enhanced greenhouse forcing resulted in overall suppression of summer precipitation, a delay in monsoon onset, and an increase in the occurrence of monsoon break periods. Weakening of the large‐scale monsoon flow and suppression of the dominant intraseasonal oscillatory modes were instrumental in the overall weakening of the South Asian summer monsoon. Such changes in monsoon dynamics could have substantial impacts by decreasing summer precipitation in key areas of South Asia.

Based on the high‐resolution gridding data (CN05) from 2416 station observations, a grid dataset of temperature and precipitation extreme indices with the resolution of 0.5° × 0.5° for China region was developed using the approach recommended by the Expert Team on Climate Change Detection and Indices. This article comprehensively presents temporal and spatial changes of these indices for the time period 1961–2010. Results showed widespread significant changes in temperature extremes consistent with warming, for instance, decreases in cold extremes and increases in warm extremes over China. The warming in the coldest day and night is larger than the warmest day and night, respectively, which is concurrent with the coldest night larger than the coldest day and the warmest night larger than the warmest day. Changes in the number of the cold and warm nights are more remarkable than the cold and warm days. Changes in precipitation extremes are, in general, spatially more complex and exhibit a less widespread spatial coverage than the temperature indices, for instance, the patterns of annual total precipitation amount, average daily precipitation rate, and the proportion of heavy precipitation in total annual precipitation are similar with negative trends in a southwest–northeast belt from Southwest China to Northeast China while positive trends in eastern China and northwestern China. The consistency of changes in climate extremes from the CN05 with other datasets based on the stations and reanalyses is also analysed.

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Results show that RegCM3 reproduces the observed spatial structure of surface air temperature and precipitation well. Changes in mean temperature and precipitation in December-January-February (DJF) and June-July-August (JJA) during the middle and end of the 21st century are analyzed. Significant future warming is simulated by RegCM3. This warming becomes greater with time, and increased warming is simulated at high latitude and high altitude (Tibetan Plateau) areas. In the middle of the 21st century in DJF, a general increase of precipitation is found in most areas, except over the Tibetan Plateau. Precipitation changes in JJA show an increase over northwest China and a decrease over the Tibetan Plateau. There is a mixture of positive and negative changes in eastern China. The change pattern at the end of the century is generally consistent with that in mid century, except in some small areas, and the magnitude of change is usually larger. In addition, the simulation is compared with a previous simulation of the RegCM3 driven by a different global model, to address uncertainties of the projected climate change in China.climate change, regional climate model, China, numerical simulation, uncertainty Citation:Gao X J, Shi Y, Zhang D F, et al. Climate change in China in the 21st century as simulated by a high resolution regional climate model.

A high-resolution climate change simulation at a grid spacing of 25 km was conducted over East Asia with the Abdus Salam International Centre for Theoretical Physics' (ICTP) regional climate model RegCM3, for the period 1951−2100. The model is driven at the lateral boundaries by the global model CCSR/NIES/FRCGC MIROC3.2_hires. Two time slices, 1961− 1990 for present-day and 2071−2100 for future climate conditions were analyzed and compared with a previous high-resolution simulation of RegCM3 driven by the NASA/NCAR global model FvGCM. The focus of the present paper is on mean temperature and precipitation and their changes during the monsoon season (May−September). Overall, for present-day conditions, the regional model improves the simulation of both temperature and precipitation patterns compared to the driving global climate models, with greater agreement between the RegCM3 simulations than with the corresponding driving models. When driven by the 2 global models, RegCM3 simulates a consistent precipitation change pattern over western China, characterized by an increase over the northwest and a decrease over the Tibetan Plateau and Southwest China. These latter precipitation decreases have opposite signs compared those from the driving global models, and the causes of these differences (mostly associated with the different topographic representations) are discussed in the paper. This implies that over these regions the internal model physics and processes can be dominant factors. On the other hand, warming patterns are essentially driven by the large-scale boundary forcing. Our results show that precipitation change projections by current global models need to be considered cautiously and that the use of nested regional models adds an element of uncertainty which needs to be properly characterized.

Comparison of convective parameterizations in RegCM4 experiments over China with CLM as the land surface model GAO Xue-Jie a , SHI Ying b and Filippo GIORGI c a climate change research center, institute of Atmospheric physics, chinese Academy of sciences, Beijing, china; b national climate center, china meteorological Administration, Beijing, china; c the Abdus salam international centre for theoretical physics, trieste, italy