A large population in China has been exposed to both severeozone (O 3 ) pollution and extreme heat under global warming. Here, thespatiotemporal characteristics of coupled extremes in surface O 3 andheat (OPCs) over China are investigated using surface observations, aprocess-based chemical transport model (GEOS-Chem), and multi-modelsimulations from Phase 6 of the Coupled Model Intercomparison Project(CMIP6). North China Plain (NCP; 37–41 ∘  N; 114–120 ∘  E)is identified as a hot spot of OPCs, where more than half of the O 3 pollution days are accompanied by high temperature extremes. OPCs over NCPexceeded 40 d during 2014–2019, exhibiting an increasing trend. BothO 3 concentrations and temperatures are elevated during OPCs compared withO 3 pollution days occurring individually (OPIs). Therefore, OPCs imposemore severe health impacts to humans than OPIs, but the stronger healtheffects are mainly driven by the higher temperatures. GEOS-Chem simulationsfurther reveal that enhanced chemical production resulting from hot andstable atmospheric conditions under anomalous weather patterns primarilycontributes to the exacerbated O 3 levels during OPCs. In the future,CMIP6 projections suggest increased occurrences of OPCs over NCP in themiddle of this century, but by the end of this century, OPCs may decrease orincrease depending on the pollutant emission scenarios. However, for allfuture scenarios, extreme high temperatures will play an increasinglyimportant role in modulating O 3 pollution in a warming climate.

Dust is an important aerosol affecting air quality in China in the winter andspring seasons. Dust in China is potentially influenced by the interannualclimate variability associated with El Niño. Here, the impacts of ElNiño with different temporal and spatial types on dust pollution inboreal winter and spring in China and the potential mechanisms areinvestigated using a state-of-the-art Earth system model (E3SMv1). We findthat the eastern Pacific (EP) and central Pacific (CP) El Niño bothincrease wintertime dust concentrations by 5–50  µ g m −3 overcentral-eastern China. Due to a stronger wind and lower relative humidity,which favor dust emissions near sources, and a strengthened northwesterlyand reduced precipitation, which are conducive to dust transport, dustconcentrations during the CP El Niño are 5–20  µ g m −3 higherin northern China than during the EP El Niño, although the changes aremostly insignificant. El Niño with a short duration (SD) increasesboreal winter dust concentrations by 20–100  µ g m −3 overnorthern China relative to the climatological mean, while there is adecrease of 5–50  µ g m −3 during the long-duration (LD) ElNiño, which is also related to the El Niño-induced changes inatmospheric circulation, precipitation, and relative humidity. In thefollowing spring season, all types of El Niño events enhance dust overnorthern China, but only the increase during the LD El Niño isstatistically significant, suggesting that the weaker intensity but longerduration of the LD El Niño events can significantly affect spring dustin China. Our results contribute to the current knowledge of the influence ofEl Niño on dust pollution, which has profound implications for airpollution control and dust storm prediction.