The ocean losing its breath under the heatwaves

The world's oceans face increasing heatwaves due to climate change, yet their impacts on dissolved oxygen—a key determinant of marine habitability—remain insufficiently understood. Using in situ observations and simulations from a fully coupled Earth system model, this study provides a global assessment of how marine heatwaves relate to low-oxygen extreme events in the surface ocean (0–10 m). We find a marked rise in the co-occurrence of marine heatwaves and low-oxygen extremes, with hotspots especially in high-biomass regions. Concurrent events are primarily driven by long-term anthropogenic warming, while internal climate variability modulates their spatial distribution. The results indicate the ocean is increasingly "losing its breath" under heatwaves, suggesting greater ecological risk than previously anticipated.

Changyu Li, Jianping Huang, Xiaoyue Liu, Lei Ding, Yongli He, Yongkun Xie