A Global Assessment of Coastal Marine Heatwaves and Their Relation With Coastal Urban Thermal Changes

Abstract Ocean temperature significantly influences global and regional weather and climate. Coastal marine heatwaves (MHWs) do not only profoundly impact marine ecosystems but can influence the climate of coastal regions. This study provides the first observational assessment of global coastal MHWs changes, showing a latitudinal‐dependent pattern with considerably strengthened severity of MHWs in the past four decades. Coastal MHWs have been found closely linked to remarkable changes in coastal urban thermal environments, showing consistent trends of increase in air temperature and moisture, and mostly reduced wind speed among 38 major coastal cities. These effects collectively exacerbate the thermal discomfort during the warm season. The findings demonstrate the strong coupling of coastal oceans and lands under the influence of global warming and regional interactions of ocean, land, and the atmosphere, and contribute to a global initial understanding of the characteristics and co‐variation of thermal extremes over the coastal regions.