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More than 1000 years, the Meiyu–Baiu have shaped the uniqueness of natural resources, civilization and culture in the Yangtze River Basin of China and the main islands of Japan. In recent decades, frequent rainstorms and droughts have seemingly diminished the misty features of traditional Meiyu–Baiu rainfall. However, there is still no consensus on whether their traditional nature is suspended. In this study, we quantitatively demonstrate that the Meiyu–Baiu almost completely lost their traditional features during 1961–2023, ∼80% of which can be attributed to anthropogenic warming. Furthermore, in a warmer future, the traditional Meiyu–Baiu will be more unlikely to appear. This study underscores the urgency in adapting to climate shift because destructive extremes are measurably taking the place of mild and maternal rains. [ABSTRACT FROM AUTHOR]

This study examines August droughts in northern China (north of 35°N) at interannual and interdecadal timescales. During the period from 1968 to 1992, the precipitation in the western and eastern regions of northern China showed an out‐of‐phase pattern. During the period from 1994 to 2018, the climate in the Tarim Basin became wetter, but there was no significant connection with drought in North China. Further studies demonstrated that the Atlantic sea surface temperature (SST) and regional soil moisture anomalies were related to drought changes in northern China. Before the early 1990s, the east‐west standardized precipitation index dipole mode in northern China was physically linked with the wet soil in central Asia in the preceding June; moreover, the wet land surface could persist until August and cause anticyclonic and cyclonic systems over Mongolia and the subtropical northwestern Pacific, thus contributing to precipitation surplus in northwest China and a deficit in North China. After the early 1990s, however, wet conditions over the Tarim Basin were related to wet soil in the East European Plain in the preceding July: the wet soil could persist into August and generate anomalous circulation over the Tarim Basin, leading to abnormal humidity. Additionally, the SST conditions in the North (South) Atlantic are key sources of climate predictability for northern China drought at the interseasonal scale after (before) the early 1990s. Key Points: The spatial distribution of the standardized precipitation index in northern China shows a marked zonal dipole patternThe drought in northern China underwent a remarkable interdecadal change in approximately 1992The Atlantic sea surface temperature and regional soil moisture anomalies were responsible for the drought changes in northern China [ABSTRACT FROM AUTHOR]

Based on the long-term reanalysis datasets and the multivariate copula method, this study reveals that the frequency of summer hot drought events (SHDEs) over northeastern China (NEC) shows interdecadal variations during 1925–2010. It is revealed that the summer sea surface temperature (SST) over the North Atlantic has a significant positive correlation with the frequency of SHDEs over NEC on the decadal time scale, indicating a potential influence of the Atlantic multidecadal oscillation (AMO). Further analyses indicate that during the positive phases of the AMO, the warming SST over the North Atlantic can trigger a stationary Rossby wave originating from the North Atlantic, which splits into two wave trains propagating along two different routes. One is a zonally orientated wave train that resembles the Silk Road pattern, whereas the other is an arching wave train that resembles the polar–Eurasian pattern. A negative (positive) phase of the Silk Road pattern (polar–Eurasian pattern) may result in the weakened westerly wind along the jet stream, the downward vertical motion, and the anomalous positive geopotential center over NEC, providing favorable conditions for precipitation deficiency and high temperature and resulting in increased SHDEs. Thus, the Silk Road pattern and the polar–Eurasian pattern serve as linkages between the AMO and SHDEs over northeastern China in summer on the interdecadal time scale. Model simulations from CAM4 perturbed with warmer SST in the North Atlantic show precipitation deficiency and high temperature conditions over northeastern China in summer, supporting the potential impacts of the North Atlantic SST on SHDEs over northeastern China. The results suggest that the phase of the AMO should be taken into account in the decadal prediction of SHDEs over northeastern China in summer. [ABSTRACT FROM AUTHOR]

ABSTRACT This study aimed to characterize present and future drought changes over eastern China using observations and Coupled Model Intercomparison Project Phase 5 ( CMIP5) simulations. We used the standardized precipitation evapotranspiration index ( SPEI) to characterize droughts at the timescales of 3- and 12-month. We distinguished the spatial patterns of drought regimes ( DRs) using the rotated empirical orthogonal function ( EOF) on the SPEI. Our results identified three DRs centered in northern China ( DR1), northeastern China ( DR2), and southern China ( DR3). Droughts in these regimes have increased in recent decades. Most CMIP5 models reproduce at least two of the DRs. The rotated EOF results indicate that the three DRs can jointly explain 46-68% of the SPEI variance (compared with approximately 60% in the observations). Among the 33 CMIP5 models analysed in this study, 13 simulated all three DRs well and showed a strong correlation pattern (>0.5). Further analysis indicated that both the external natural and greenhouse gas forcing experiments in CMIP5 reproduced the DRs, implying that natural variability and anthropogenic activity play important roles in the formation of these DRs. With continued climate warming, the three DRs over eastern China will persist. Despite the uncertainties in drought changes that mainly depend on the potential evapotranspiration methods, climate model results suggest that droughts would be aggravated under warming scenarios. The probability of severe droughts increase by the end of the century: 33% in DR1, 25% in DR2, 34% in DR3 in RCP4.5 and almost double in RCP8.5 scenario in Thornthwaite method based SPEI estimates. [ABSTRACT FROM AUTHOR]

Historical records have indicated an increase in high-impact drought occurrences across China during recent decades, but whether this increase is due to natural variability or anthropogenic change remains unclear. Thus, the shift toward dry conditions and their associated attributions across China are discussed in this study, primarily regarding the standardized precipitation evapotranspiration index (SPEI). The results show that drought occurrences across China increased consistently during 1951–2014, especially during the recent twenty years. Most of the increased drought events happened under warm-dry conditions that coincided with relatively high temperature anomalies but without large anomalies in annual precipitation, implying an increase in hot drought events across China. Further analysis revealed that the change in drought occurrences were mainly due to the combined activity of external natural forcings and anthropogenic changes across China. However, external natural forcings were mainly responsible for the variability of droughts and anthropogenic influences for their increasing trends, suggesting that anthropogenic warming has increased hot drought occurrences, associated risks and impacts across China. With continued warming in the future, the impact of anthropogenic warming on the increased hot drought events will be further amplified. The probability of warm years is projected to significantly increase, and the occurrence probability of hot drought events (SPEI < −1.0) will increase to nearly 100% by the year 2050, even though the annual precipitation is projected to increase across China in the future. [ABSTRACT FROM AUTHOR]

The standardized precipitation evapotranspiration index (SPEI) is computed and compared in China using reference evapotranspiration calculated using the Thornthwaite (TH) approach and the Penman-Monteith (PM) equation. The analysis reveals that SPEI_PM outperforms the SPEI_TH with regard to drought monitoring during the period 1961-2012 over China, especially in arid regions of China. Furthermore, the SPEI_PM also performs better with regard to observed variations in soil moisture and streamflow in China. Thus, changes in drought characteristics over China are detected on the basis of variations in the SPEI_PM. The results indicate that droughts over China exhibit pronounced decadal variations over the past 50 yr, with more frequent and severe droughts occurring before the 1980s and in the 2000s compared with the 1980s and 1990s. Since the late 1990s, droughts have become more frequent and severe across China, especially in some regions of northern China. Concurrently, consecutive drought events have also increased across China. This suggests that dry conditions in China have been enhanced in recent years. Further analyses illustrate that the temperature and precipitation anomalies exhibit different roles in detecting droughts across China, which is primarily due to the magnitude of their variations and different climate variability. Considering temperature and precipitation perturbations, droughts exhibit relatively larger responses to temperature fluctuations in northern China and relatively larger responses to precipitation anomalies in southern China. [ABSTRACT FROM AUTHOR]

Climate change is expected to influence the occurrence and magnitude of precipitation-related extremes and to increase drought and flood risk. Thus, future changes in dryness and wetness over global land areas are analysed using future climate simulations from the World Climate Research Programme's (WCRP) Coupled Model Intercomparison Project Phase 5 (CMIP5) under RCP4.5 forcing scenario. Model reproducibility is evaluated first, and it is shown that high performance can be achieved in present-day climate simulations by models, particularly in multi-model ensemble (MME) results. For future climate simulations, the highest reliability regarding changes in precipitation and its related extremes is found over Northern high latitudes, while the lowest confidence levels are mainly localized over the tropics. The projections indicate a high likelihood that there will be a shift to fewer dryness but to more extreme precipitation events or/and flood events in future over Northern high latitudes. Among populated areas, Mediterranean basin is highlighted as displaying a relatively high reliability of increases in both dryness and wetness indicators, implying increased probabilities of both drought and flood events, despite the fact that there would be less precipitation. In North America and Asian monsoon areas, dryness indictors show no obvious changes, while markedly increases are found in wetness indicators, concurrent with a high model agreement. In contrast, southern Africa, Australia, and the Amazon basin show relatively high reliability regarding increases in dryness, but a low confidence level in wetness. The severity of these changes is not uniform across annual and seasonal scales and is region dependent. Two sources of uncertainty in projections are investigated in this study: internal and inter-model variability. The analysis indicates that internal and inter-model variability are the dominant sources of uncertainty in extreme climate projections, and inter-model variability is much larger and increases with time. Further analysis shows that both sources of uncertainty generally perform lower on annual and global scales than on seasonal and regional ones. [ABSTRACT FROM AUTHOR]

This study investigates the influence of external forcings on the various summer hot drought events (SHDEs) over northeastern China (NEC). SHDEs are represented by the probability‐based index (PI), which considers precipitation and temperature anomalies. The results show that SHDEs over NEC increased from 1961 to 2005, and the experiments for historical forcing (ALL), increased greenhouse gases emission forcing (GHG), and anthropogenic forcing (ANT) can largely reproduce the spatial and temporal features of the trends of SHDEs over NEC. Based on the optimal fingerprinting method, the impact of increased anthropogenic activities can be detected at the 90% confidence level. In addition, the attributable changes of PI in response to GHG and ANT forcings resemble the observation, implying that the increasing trends of SHDEs over NEC are primarily attributed to the increased anthropogenic activity. Furthermore, the occurrence probability of SHDEs over NEC will be further increased under different Representative Concentration Pathways in the future. Additional strict control regulations on GHG emissions are thus suggested to mitigate its impact on regional climate changes. Key Points: Summer hot drought events over northeastern China are observed to increase in recent decadesEffects of anthropogenic activity emerge as an important factor to increase the summer hot drought events over northeastern ChinaThe frequency and the intensity of summer hot drought events over northeastern China will be further strengthened in the future [ABSTRACT FROM AUTHOR]

Hot drought events often have great impacts on society, the ecosystem, and agriculture. Northeastern China (NEC) is the ganary of China, thus it is quite important to investigate the characteristics of summer hot drought event (SHDE) over NEC and find the possible mechanisms. Based on the observation and the reanalysis datasets, we found that the decline of Barents Sea ice (SICBS) in March is closely related to the occurrence of summer SHDE over NEC during 1997-2016. The decline of SICBS can lead to decrease of snow depth over the western Eurasia (SDWEA) in April. On the one hand, the decline of SDWEA in April can regulate the atmospheric circulation during May-June that lead to dry soil in Yangtze River valley and northern China regions, which is further linked to SHDE over NEC. On the other hand, both the decline of SICBS in March and the decrease of SDWEA in April favor the positive Polar/Eurasia teleconnection pattern and dry soil over NEC in JA, which provides favorable atmospheric circulation patterns for SHDE over NEC. All of these results can be verified by the simulations from the Community Earth System Model and the numerical experiments that based on the version 4 of Community Atmosphere Model. Consequently, the Barents Sea ice in March might be a potential predictor for the SHDE over NEC. [ABSTRACT FROM AUTHOR]