Impacts of Climate Change on Precipitation and Marine Heatwaves: Insights from High-Resolution Earth System Models

This study investigates the impacts of climate change on marine heatwaves and extreme precipitation events associated with atmospheric rivers. First, our findings demonstrate that high-resolution models are more adept at simulating mesoscale eddies in the ocean, thereby facilitating more accurate predictions of future changes in marine heatwaves. Under climate warming, the intensity and annual days of marine heatwaves are projected to increase significantly. Even if organisms within large coastal marine ecosystems fully adapt to long-term mean warming, the escalating intensity of marine heatwaves would nonetheless pose substantial threats to these ecosystems. Furthermore, with global warming, the intensity and annual days of subsurface marine heatwaves are also expected to rise markedly on a global scale. This increase is primarily driven by the long-term rise in subsurface temperatures and changes in their variability. After accounting for the effects of long-term warming, the magnitude of increases in the intensity and annual days of subsurface marine heatwaves is notably greater than those at the surface, further exacerbating the risks posed by global warming to marine ecosystems.

Additionally, the study explores the influence of global warming on atmospheric river events in the Northern Hemisphere. High-resolution Earth system model simulations indicate that, under approximately 4°C of global warming, elevated sea surface temperatures enhance ocean-to-atmosphere moisture flux, thereby intensifying atmospheric river events. This intensification is projected to result in a doubling of the area affected by extreme precipitation events along the western coasts of Europe and North America. By disentangling the thermodynamic and dynamic contributions to intense precipitation associated with atmospheric rivers, the study identifies differences in the direction of vertical wind velocity changes as the primary source of regional disparities in dynamic contributions.