205 / 2024-09-11 13:39:14

Expanding global oxygen minimum zones restrict marine habitats under climate change

dissolve oxygen,metabolic index,climate change

Oxygen minimum zones (OMZs) are regions of the ocean where dissolved oxygen levels are extremely low, significantly affecting marine ecosystems with their expansion. Despite their significance, long-term dynamics of OMZ volumes across different depths and regions remain poorly understood due to limited observations. Moreover, the impact of OMZ expansion on the compression of marine animal habitats remains significantly underexplored. Addressing these gaps, we quantify the expansion and interannual changes of OMZs in horizontal and vertical directions from 1960 to 2022, using comprehensive multi-source observations. We demonstrate that the volume of global OMZ60 (i.e., dissolved oxygen < 60 µmol/kg) expanded by as much as 10 million km3, approximately comparable to two thirds of the volume of the Arctic Ocean. This expansion rate exceeds previous estimates by a factor of 10, highlighting a critical underestimation in current biogeochemical model predictions. Furthermore, we quantify the boundaries of suitable habitats driven by increasing oxygen depletion and rising ocean temperatures, posing a significant threat to marine biodiversity. This study not only contributes to our understanding of marine biogeography under changing climatic conditions but also underscores the critical need for conservation strategies that account for how shifts in oxygen levels due to climate change could fundamentally reshape marine ecosystems.