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Identifying the geographical regions where tropical cyclone (TC) activities are changing most is critical for policymakers to develop long‐term strategies for coastal disaster prevention. However, the key concerns for assessing the variation trends of the regional hazard caused by landfalling TCs are limited by data availability in the spatio‐temporal coverage and homogeneity. In this study, based on the high spatio‐temporal resolution ERA5 reanalysis data and a quasi‐Lagrangian approach, we investigate the long‐term variation trend of the compound hazard resulting from wind and precipitation during the landfall of the TCs in the coastal areas of China from 1980 to 2020. Two hotspot areas of TCs hazards are identified, one in the Taiwan Strait and surrounding areas, and the other in the Hainan Island and the northern South China Sea. The observed compound hazard in the former hotspot area shows a noticeable increasing trend over the past 40 years at a rate of 5% per year, while the latter hotspot area displays a robust decreasing trend. This variation pattern of the hazard trend is mainly attributed to the increased frequency of intense TCs (typhoon intensity grade and above) and the northward movement of TC track in China. The number of intense landfalling TCs in southeastern China nearly tripled in 2000–2019 compared to those in 1980–1999. The widespread increase in the compound hazard also suggests a rise in the disaster risk for the middle‐ and high‐latitude coastal regions of China, which require an immediate development and execution of advanced prevention strategies. [ABSTRACT FROM AUTHOR]

The global mean surface temperature does not increase monotonously over the past decades, with accelerated warming from the late 1970s to 1998 and followed by the warming slowdown during 1998–2013 (the so‐called warming hiatus). This study assessed and compared the temporal evolutions of sea surface temperature (SST) trends in the East China Seas (ECS, including Bohai, Yellow and East China Sea) and other key ocean regions. The results revealed an amplified response of ECS SST to both global warming acceleration and hiatus. This amplification was manifested as remarkably enhanced winter warming rates in the ECS of over 1.1 and 0.8°C⋅decade–1 for the 1980–1989 and 1990–1999, respectively, and as an obvious cooling trend of nearly −0.5°C⋅decade‑1 during 1998–2013. The enhanced response can be explained well by the combined effects of the Kuroshio Current (KC) and East Asian Winter Monsoon (EAWM). The weakened EAWM during the 1980s, accompanied by lower wind speeds and higher air temperatures, impeded the releases of latent and sensible heat fluxes from the ocean to the atmosphere, resulting in rapid ECS warming. During 1998–2013, the strengthened EAWM led to the enhanced cooling trend in the ECS. In addition, the volume transport of the KC east of Taiwan strengthened (weakened) during the 1990s (2000s), which might also have contributed to the enhanced warming (cooling) in the ECS. Our research suggests their sensitivity makes the ECS potentially vulnerable to the effects of global climate change, which has important implications regarding regional impact assessments. [ABSTRACT FROM AUTHOR]

A comprehensive investigation using the air quality network and meteorological data of China in 2015 showed that PM2.5 driven by cold surges from the ground level could travel up to 2000 km from northern to southern China within two days. Air pollution is more severe and prominent during the winter in north China due to seasonal variations in energy usage, trade wind movements, and industrial emissions. In February 2015, two cold surges traveling from north China caused a temporary increase in the concentration of PM2.5 in Shanghai. Subsequently, the concentration of PM2.5 in Xiamen increased to a high of 80 µg/m3, which is double the average PM2.5 concentration in Xiamen during the winter. This finding is a new long-range transport mechanism comparing to the well-established mechanism, with long-range transport more likely to occur in the upper troposphere than at lower levels. These observations were validated by results from the back trajectory analysis and the RAMS- CMAQ model. While wind speed was found to be a major facilitator in transporting PM2.5 from Beijing to Xiamen, more investigation is required to understand the complex relationship between wind speed and PM2.5 and how it moderates air quality in Beijing, Shanghai, and Xiamen. [ABSTRACT FROM AUTHOR]

ABSTRACT The extreme drought in Southwest China ( SWC) during the winter 2009/2010 brought catastrophic losses to the state and people. In this article, evidence has been presented that this drought event was not a single one but part of a decade-long drying period after 2000. Based on observed data from meteorological stations, we identified two distinct modes of winter precipitation in SWC: one is spatially in-phase change pattern and the other is east-west dipole pattern, both of which experienced a sharp decadal decrease since the late 1990s. The two modes are closely linked to two atmospheric circulation patterns induced by Arctic Oscillation ( AO) and El Niño, respectively. The sustained precipitation deficit in SWC after 2000 was associated with the anomalous atmospheric circulation patterns mainly caused by the decadal transition of AO towards its negative phases and frequent El Niño, especially the central Pacific El Niño. The model experiments forced by sea surface temperature anomaly patterns in the North Atlantic ( NA) and tropical Pacific ( TP), respectively, could robustly reproduce precipitation anomaly in SWC and large-scale circulation pattern. The NA SST could excite a series of quasi-stationary wave trains, which propagate eastward to the south of the Himalayas, similar to the AO-related teleconnection. The SWC is just beneath the anti-cyclonic circulation anomaly with dry conditions. In the TP experiment, the simulated ascending motion locates over the central Pacific, while the anomalous descending branch of the western Walker cell appears over the SWC, being not conducive to the formation of precipitation. [ABSTRACT FROM AUTHOR]

ABSTRACT The coastal China areas stretching from tropical to temperate zone represent major environmental and economic assets. However, knowledge of climate change and its impact in coastal seas, which is very critical for marine resource and risk-management issues, is relatively poor compared with that on land. Here, we show that the coastal China seas experienced a long-term surface warming with a rate of 0.015 °C year−1 and an obvious sea level rise along the coast, particularly along the East China Sea with a rate of more than 3.2 mm year−1 since the late 1950s. The Eurasian atmospheric circulation underwent clearly inter-decadal changes in the past decades due to the tropical ocean thermal changes including warming hiatus and conversely influenced the higher latitude coastal marine conditions through regional air-sea interaction. Marine climate variables including sea surface temperature, sea surface height, and atmospheric cyclonic circulation have formed a favourable condition for phytoplankton blooms such as harmful algae blooms (e.g. red tides) and Enteromorpha prolifera blooms (green tides). These algae blooms could strongly lower oxygen levels in the seawater and have been posing threats for the health of coastal and marine ecosystems since the late 1970s. The impacts and key risks of climate change risks in coastal China seas and the coastal zone are reviewed and analysed as follows: frequent occurrences of red tides and green tides, distribution shifts of marine species and changes in their seasonal behaviour, reduction of coastal habitat, decline of marine ecosystem services, flooding and coastal inundation, seawater intrusion, and threats to coastland community security and marine industries, etc. Furthermore, the accumulated effects of human activity, such as reclamation, sewage discharge, and overfishing, have led to an apparent increase in climate-related vulnerabilities. Adaptation issues and risk-management strategies in response to climate change are discussed and proposed as well. [ABSTRACT FROM AUTHOR]

A comprehensive investigation using the air quality network and meteorological data of China in 2015 showed that PM 2.5 driven by cold surges from the ground level could travel up to 2000 km from northern to southern China within two days. Air pollution is more severe and prominent during the winter in north China due to seasonal variations in energy usage, trade wind movements, and industrial emissions. In February 2015, two cold surges traveling from north China caused a temporary increase in the concentration of PM 2.5 in Shanghai. Subsequently, the concentration of PM 2.5 in Xiamen increased to a high of 80 µg/m 3 , which is double the average PM 2.5 concentration in Xiamen during the winter. This finding is a new long-range transport mechanism comparing to the well-established mechanism, with long-range transport more likely to occur in the upper troposphere than at lower levels. These observations were validated by results from the back trajectory analysis and the RAMS- CMAQ model. While wind speed was found to be a major facilitator in transporting PM 2.5 from Beijing to Xiamen, more investigation is required to understand the complex relationship between wind speed and PM 2.5 and how it moderates air quality in Beijing, Shanghai, and Xiamen.