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This study reports model assessments and future projections of the Coupled Model Intercomparison Project Phase 6 (CMIP6) models in simulating spring climate extremes over China and its eight subregions. The CMIP6 models are generally able to capture mean climate extremes and trends but have common deficiencies such as topography‐related cold‐temperature biases and precipitation overestimations. The CMIP6 multimodel median ensemble (MME) typically outperforms the individual models in simulating spring climate extremes. However, in terms of the model performance metrics, almost no models show better performance in reference to all indices compared to the observations. Furthermore, we investigate the future changes in these indices on national and regional scales over the near‐term (2021–2040), mid‐term (2041–2060), and long‐term (2081–2100) future periods relative to the 1995–2014 reference period under four Shared Socioeconomic Pathway (SSP) scenarios: SSP1‐2.6, SSP2‐4.5, SSP3‐7.0, and SSP5‐8.5. By the end of the 21st century, wet and warm extreme climate events are projected to increase, particularly in northern and western China. While dry and cold extreme climate events are projected to decrease, particularly in southern China. Additionally, the future projections of both temperature and precipitation extreme indices are remarkable under the high‐greenhouse‐gas (GHG)‐emission scenarios, with the projected changes exceeding those expected under the low‐GHG scenarios. [ABSTRACT FROM AUTHOR]

The observed spatial–temporal variations in daily snowfall over the Eurasian continent from 1980 to 2019 are explored in this study. The results show that the snowfall amount and its number of days are mainly centred in the high latitudes and high terrain regions of the Eurasian continent (such as North Asia), while they are relatively small in Southern Europe, Central Asia and East Asia. During the past decades, a decreasing trend can be observed for snowfall amounts and the numbers of days over most regions of Eurasia, while increases are clear in terms of the mean intensity. In response to climate warming in recent decades, the first date of snowfall occurrence postponed and the ending date advanced across the Eurasian continent. Furthermore, the change characteristics of the different grades of snowfall are also investigated across this region, including light snowfall, moderate snowfall, heavy snowfall and snowstorm. The light snowfall and number of days show a decreasing tendency, which mainly results in a decrease in the total snowfall amount and number of days. However, the amounts of heavy snowfall and snowstorms and their numbers of days are significantly increased, implying that the Eurasian continent has experienced increased severe snowfall events during recent decades. [ABSTRACT FROM AUTHOR]

A comparison assessment of model capabilities in simulating precipitation extremes across China was first implemented by using 30 models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) and using 36 CMIP6 models. The results indicate that the multi‐model median ensembles (MME) of both the CMIP5 and CMIP6 models can reasonably reproduce the climate means for the period from 1986 to 2005, and the biases are lower in most CMIP6 models compared to the CMIP5 models, especially over southern China. To provide further comparisons, 14 CMIP6 models are selected and compared with their predecessors in CMIP5. The results show that the CMIP6 models generally exhibit superior skill in simulating the extreme precipitation indices over China. The model spreads for most of the extreme indices in the CMIP6 version are also smaller. Additionally, the MMEs of the two CMIPs outperform individual models. However, some CMIP6 models also exhibit weaker skill levels in simulating some particular indices compared with those in CMIP5, which merits further investigation. The results from seven reanalyses further show large uncertainties for these indices; therefore, care should be taken in comparison with reanalyses. For future changes in precipitation extremes, total wet day precipitation (PRCPTOT), maximum 5‐day precipitation (RX5day) and very heavy precipitation days (R20mm) are projected to clearly increase across China over the coming century under the shared socioeconomic pathway (SSP) 2‐4.5 and SSP5‐8.5 scenarios. However, the dry condition index of CDD exhibits a decreasing tendency in the future, which implies that the dry conditions induced by precipitation anomalies will be mitigated. However, large uncertainties are still observed for future changes, which are primarily sourced from inter‐model and scenario variabilities, especially for the projected changes at the end of the 21st century. [ABSTRACT FROM AUTHOR]

This study assessed the capability of the historical simulations of phase 5 and 6 of the Coupled Model Intercomparison Project (CMIP5/6) in reproducing the temporal and spatial characteristics of the Interdecadal Pacific Oscillation (IPO) and its impact on global surface air temperature (SAT), surface equivalent potential temperature (Thetae_sfc) and precipitation. The IPO index time series simulated by CMIP5/6 models deviated from observations and struggled to capture the phase evolution characteristics of the IPO. Nevertheless, CMIP5/6 models successfully captured the horseshoe‐shaped sea surface temperature anomaly in the Pacific. Additionally, the CMIP5/6 models were able to simulate the IPO's 10–30‐year period. Notably, the simulated IPO index exhibited a statistically significant upward trend, which was absent in observations. Additionally, the IPO‐related global land SAT, Thetae_sfc and precipitation simulated by CMIP5/6 models performed differently in boreal winter and boreal summer. Furthermore, the IPO‐related global land SAT performed better in CMIP5/6 models during boreal winter than that in boreal summer. In CMIP6 models, it improved during both boreal winter and summer compared to CMIP5 models. In terms of the IPO‐related global land Thetae_sfc, CMIP5/6 models also performed better during boreal winter than in boreal summer. However, CMIP5 models outperformed CMIP6 models during the boreal summer. In terms of the IPO‐related global land precipitation, CMIP5/6 models performed better during boreal summer compared to boreal winter. Moreover, the IPO‐related global land precipitation in CMIP6 models improved significantly in boreal winter, but almost the same in boreal summer, compared to CMIP5 models. Further studies showed that the enhancements in simulating IPO's spatial pattern did not correspond to improvements in the model's ability to simulate IPO's global teleconnections. [ABSTRACT FROM AUTHOR]

This study aims to characterize future changes in precipitation extremes over China based on regional climate models (RCMs) participating in the Coordinated Regional Climate Downscaling Experiment (CORDEX)-East Asia project. The results of five RCMs involved in CORDEX-East Asia project that driven by HadGEM2-AO are compared with the simulation of CMA-RegCM driven by BCC-CSM1.1. Eleven precipitation extreme indices that developed by the Expert Team on Climate Change Detection and Indices are employed to evaluate precipitation extreme changes over China. Generally, RCMs can reproduce their spatiotemporal characteristics over China in comparison with observations. For future climate projections, RCMs indicate that both the occurrence and intensity of precipitation extremes in most regions of China will increase when the global temperature increases by 1.5/2.0 °C. The yearly maximum five-day precipitation (RX5D) averaged over China is reported to increase by 4.4% via the CMA-RegCM under the 1.5 °C warming in comparison with the baseline period (1986–2005); however, a relatively large increase of 11.1% is reported by the multi-model ensemble median (MME) when using the other five models. Furthermore, the reoccurring risks of precipitation extremes over most regions of China will further increase due to the additional 0.5 °C warming. For example, RX5D will further increase by approximately 8.9% over NWC, 3.8% over NC, 2.3% over SC, and approximately 1.0% over China. Extremes, such as the historical 20-year return period event of yearly maximum one-day precipitation (RX1D) and RX5D, will become more frequent, with occurrences happening once every 8.8 years (RX1D) and 11.5 years (RX5D) under the 1.5 °C warming target, and there will be two fewer years due to the additional 0.5 °C warming. In addition, the intensity of these events will increase by approximately 9.2% (8.5%) under the 1.5 °C warming target and 12.6% (11.0%) under the 2.0 °C warming target for RX1D (RX5D). [ABSTRACT FROM AUTHOR]

Previous studies have documented that the summer precipitation over South China (SC) has experienced a prominent inter-decadal increase in 1992/1993, and the possible mechanism has been well revealed. The aim of this study is to investigate the changes in extreme precipitation and clustered extreme precipitation events in recent decades using station observations and the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data. The results indicate that extreme precipitation also experienced a significant inter-decadal increase around 1992/1993. Significant changes can also be found in the associated atmospheric circulations, such as the western North Pacific subtropical high (WNPSH) and the westerly jet stream over East Asia. In addition, the water vapour transport (WVT) related to extreme precipitation differed from mean conditions. For extreme precipitation events, the WVT from the Northwest Pacific and Indian Oceans was much stronger when compared with mean precipitation. When extreme precipitation events were clustered, the increased WVT mainly originated from the South China Sea and Northwest Pacific Ocean. Further analysis indicates that the WVT increased from the Indian Ocean but decreased from the Northwest Pacific after 1992/1993; this inding explains the significant increase in the clustered extreme precipitation events over SC after 1992/1993. In addition, the atmospheric stratification has become more unstable since 1992/1993. [ABSTRACT FROM AUTHOR]