Every body of water on the planet - oceans, rivers, lakes - needs dissolved oxygen to keep the life inside it going. The team highlights three things driving it - human-caused warming, nutrient pollution from agriculture and industry, and changes in how deeper water circulates. The review linked aquatic deoxygenation to warming, nutrient pollution and disrupted water circulation, with some impacts potentially persisting for centuries. According to the review, falling oxygen levels mess with the biological and chemical processes that help keep the climate in check. "Mitigating its impacts represents a critical component of maintaining biodiversity and climate," Ferrer said.