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The wet bulb temperature (Tw) has gained considerable attention as a crucial indicator of heat-related health risks. Here we report south-to-north spatially heterogeneous trends of Tw in China over 1979-2018. We find that actual water vapor pressure (Ea) changes play a dominant role in determining the different trend of Tw in southern and northern China, which is attributed to the faster warming of high-latitude regions of East Asia as a response to climate change. This warming effect regulates large-scale atmospheric features and leads to extended impacts of the South Asia high (SAH) and the western Pacific subtropical high (WPSH) over southern China and to suppressed moisture transport. Attribution analysis using climate model simulations confirms these findings. We further find that the entire eastern China, that accommodates 94% of the country's population, is likely to experience widespread and uniform elevated thermal stress the end of this century. Our findings highlight the necessity for development of adaptation measures in eastern China to avoid adverse impacts of heat stress, suggesting similar implications for other regions as well. Attributing spatially heterogeneous heat stress trends to water vapor pressure changes driven by climate change-induced rapid warming in high-latitudes of East Asia, the authors predict widespread and uniform future heat stress in eastern China. [ABSTRACT FROM AUTHOR]

The onset of the South China Sea summer monsoon (SCSSM) has profound impacts on meteorological conditions over East Asia. However, whether the interannual variability in monsoon onset date impacts ozone (O3) pollution remains unclear. Here, we investigate the relationship between early onset of SCSSM and late spring O3 in southern China. Our results show notable differences in surface O3 concentrations before and after SCSSM onset during early onset events in southern China. The enhanced O3 of 11.1 μg m−3 is supported by increased air temperature and solar radiation of 1.1 K and 30.9 W m−2 and reduced relative humidity of −5.7%. Both observation and model simulations confirm that O3‐favorable meteorological conditions modulated by early SCSSM onset can be found in May. It increases the boundary layer height and biogenic emissions of volatile organic compounds, enhancing O3 by 10 μg m−3 over southern China. Chemical processes dominate such increases in O3 with enhanced chemical production of 0.27 Tg month−1. Descending motion in southern China vertically transports O3 to surface by 0.10 Tg month−1, whereas horizontal advection reduces O3 concentration by 0.12 Tg month−1. The meteorological responses to colder sea surface temperature (SST) in the central equatorial Pacific are pronounced, leading to higher O3 concentrations over the Yangtze River Delta, while warmer SST in the Philippine Sea contributes O3 over the Pearl River Delta and eastern China. This study highlights the importance of SCSSM onset with respect to O3 in southern China, with promising applications in management of air pollution and agriculture. Plain Language Summary: The onset of the South China Sea summer monsoon (SCSSM), a spectacular feature of the Asian summer monsoon, has significant impacts on meteorological conditions over East Asia. It remains unclear whether the interannual variability in monsoon onset date affects ozone (O3) pollution. In this study, we demonstrated that the early onset of SCSSM can create warmer and drier conditions with enhanced solar radiation in May, which increases boundary layer height, boosts biogenic emissions of volatile organic compounds and worsens O3 pollution in southern China. By integrating reconstructed O3 data set and meteorological reanalysis together with model simulations, we found that increased O3 concentrations of approximately 10 μg m−3 over southern China were dominated by enhanced chemical production. Both sea surface temperature anomalies in the central equatorial Pacific and Philippine Sea contributed to the O3‐favorable meteorological conditions modulated by early SCSSM onset. Our study emphasizes the importance of considering the SCSSM onset in understanding O3 pollution in southern China, with promising applications in air pollution management and agriculture. Key Points: Early onset of the South China Sea summer monsoon can create warmer and drier conditions with enhanced solar radiation in MayEnhanced chemical production dominates the worsening late spring ozone pollution in southern China during early onset eventsBoth sea surface temperature anomalies in the central equatorial Pacific and Philippine Sea contribute to higher ozone in southern China [ABSTRACT FROM AUTHOR]

Methane (CH4) is the second most potent greenhouse gas (GHG), and China emerges as the largest anthropogenic CH4 emitter by country. Current limited CH4 monitoring systems in China are unfortunately inadequate to support carbon management. Here we use the Weather Research and Forecasting model (WRF) coupled with a GHG module and satellite constrained emissions to simulate the spatiotemporal distribution of CH4 over East Asia in 2017. Model evaluations using both satellite retrievals and ground-based observations indicate reliable performance. We further inter-compare four proper orthogonal decomposition (POD)-based sensor placement algorithms and find they are able to capture main spatial features of surface CH4 under an oversampled condition. The QR pivot algorithm exhibits superiority in capturing high CH4, and it offers the best reconstruction with both high efficiency and accuracy. Areas with high CH4 concentrations and intense anthropogenic activities remain underrepresented by current CH4 sampling studies, leading to notable reconstruction error over central and eastern China. Optimal planning of 160 sensors guided by the QR pivot algorithm can yield reasonable reconstruction performance and costs of site construction. Our results can provide valuable references for future planning of CH4 monitoring sites. [ABSTRACT FROM AUTHOR]

To investigate the association between particulate matter and the incidence, disability, and mortality of stroke, we reported the burden of stroke attributable to particulate matter (PM 2.5) pollution, including ambient particulate matter pollution (APMP) and household air pollution from solid fuels (HAP), from 1990 to 2019. We retrieved the detailed data on the burden of stroke attributable to PM 2.5 from the Global Burden of Disease (GBD) 2019. The number of disability-adjusted life-years (DALYs) and deaths, age-standardized death rates (ASMR), and age-standardized disability-adjusted life-years rates (ASDR) attributable to PM 2.5 were estimated by age, sex, geographical location, socio-demographic index (SDI), and stroke subtypes (ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage). The estimated annual percentage change (EAPC) was calculated to assess the trends in ASDR and ASMR during the period 1990–2019. Regarding stroke subtypes, the proportion of ischemic stroke burden is increasing, while intracerebral hemorrhage carries the heaviest burden. Both APMP and HAP contributed the most to stroke-related deaths and DALYs of stroke among the elderly populations and males. The highest ASDR and ASMR of stroke attributable to APMP were in the middle SDI regions, especially in East Asia. For HAP, the highest ASDR and ASMR were in the low SDI regions, mainly in Oceania. From 1990–2019, in terms of the EAPC results, APMP caused an increased burden of stroke, whereas the impact of HAP significantly fell. The most pronounced increase in ASDR and ASMR for strokes attributed to APMP were in the low-middle SDI and low SDI regions, particularly among the 25–35 age group. Stroke attributed to PM 2.5 is a global health problem, and the patterns and trends were heterogeneous across APMP and HAP. Targeted interventions should be formulated for APMP and HAP. • Stroke attributable to APMP increased more significantly for younger age groups. • HAP is on a downward trend compared to APMP, but still not negligible. • a significant increase in ischemic stroke in young people. • Significant increase in intracerebral hemorrhage in the elderly. [ABSTRACT FROM AUTHOR]