Responses of Horizontally Expanding Oceanic Oxygen Minimum Zones to Climate Change Based on Observations

Due to climate change, global oceanic dissolved oxygen (DO) has been decreasing, and oxygen minimum zones (OMZs) have been expanding. Here, we estimate the annual global and regional OMZ areas using geostatistical regression combined with Monte Carlo. From 1960 to 2019, annual global OMZ20 (DO < 20 mu mol/kg) and OMZ60 (DO < 60 mu mol/kg) areas cover 5%-14% and 15%-32% of the global ocean, respectively. The global and most regional OMZ areas after the late 2000s were all significantly larger than those in previous years. Most oceanic regions likely experienced significant expansions in OMZ areas, especially the North Pacific. However, the equatorial Pacific with the largest OMZ area showed insignificant horizontal expansion. The expanding OMZ areas of most oceans responded more quickly and effectively to the surrounding sea temperatures than to the sea surface temperatures. Our research highlights the need for marine resource management to account for the challenges from OMZs.

Automated summary

Global oceanic dissolved oxygen is decreasing and oxygen minimum zones are expanding due to climate change. This research estimates the annual global and regional areas of these zones and finds significant expansions since the late 2000s, particularly in the North Pacific.