The ocean is being suffocated by a lack of oxygen

New research predicts that 70 percent of the world’s oceans could be choking from a lack of oxygen caused by climate change. The new model that the research is based on found that mid-level oceans, which support many global fisheries, are already losing oxygen at an unusual rate. The study also shows that a critical threshold of oxygen loss was passed in 2021. 

The researchers found that midwater ocean areas, with depths between 200 to 1,000 meters, are especially vulnerable to deoxygenation. This is because these depths are not replenished by oxygen from the atmosphere or photosynthesis, and decomposition of algae happens here.  

“This zone is actually very important to us because a lot of commercial fish live in this zone,” said study lead author Yuntao Zhou, an oceanographer at Shanghai Jiao Tong University. “Deoxygenation affects other marine resources as well, but fisheries (are) maybe most related to our daily life.”

The research just further highlights the vulnerability of our world’s oceans and the continuing threat of climate change. Not only are the oceans important as a source of fish consumed as food, but they also play a role in Earth’s atmosphere and water supply as well. 

“Humanity is currently changing the metabolic state of the largest ecosystem on the planet, with really unknown consequences for marine ecosystems. That may manifest in significant impacts on the ocean’s ability to sustain important fisheries,” said Matthew Long, an oceanographer at NCAR who was not involved in the study. 

The researchers also discovered that waters closer to the poles are more vulnerable to deoxygenation but are uncertain as to why. 

“The oxygen minimum zones actually are spreading into high latitude areas, both to the north and the south. That’s something we need to pay more attention to,” said Zhou. “Even if global warming were to reverse, allowing concentrations of dissolved oxygen to increase, whether dissolved oxygen would return to pre-industrial levels remains unknown.”

The study is published by the American Geophysical Union in the journal Geophysical Research Letters.

—By Zach Fitzner, Earth.com Staff Writer