Oxygen, the element that sustains nearly all multicellular life on Earth, is disappearing from the world’s aquatic ecosystems. In a new review, scientists warn that this rapidly escalating, human-driven crisis threatens to upend the biosphere. The paper, published June 30 in the journal Limnology and Oceanography, argues that aquatic deoxygenation should be added to the Planetary Boundaries framework. First introduced by a group of 28 internationally renowned scientists in 2009, the framework identifies nine ways that humanity is pushing crucial processes that maintain Earth’s stability and resilience past their limits. They are climate change, ocean acidification, biodiversity loss, atmospheric aerosol loading, stratospheric ozone depletion, freshwater change, land-use change, chemical pollution, and biogeochemical flows. “The health and stability of our planet depends on the health and stability of aquatic ecosystems, which need oxygen to function normally,” lead author Erica Ferrer, a postdoctoral scholar at the University of California, Santa Barbara’s National Center for Ecological Analysis and Synthesis, said in a statement. “This study is designed to elevate the profile of aquatic deoxygenation as a global threat and show that it does not operate in isolation.”