🌅 The Earth’s Waters Are Losing Oxygen

SOURCE

Guan et al. (2026)

WHAT TO KNOW

• Researchers at the Chinese Academy of Sciences analyzed 3.4 million satellite images of more than 21,000 rivers worldwide, finding oxygen levels have declined in 78.8% of the studied rivers since the 1980s. The authors found global climate change has reduced rivers’ oxygen solubility (i.e., a body of water’s ability to hold dissolved oxygen), accounting for 62.7% of the observed decline, with heatwaves in particular found to be responsible for 22.7% of river deoxygenation. The loss of oxygen in water threatens aquatic life, impacts ecological food webs, and leads to the production of greenhouse gases known to cause global warming.

WHY IT MATTERS

• The present study is one of several recent global analyses that have found the Earth’s waters are losing oxygen at an alarming rate. A 2024 study by an international team of researchers found lakes (5.5% oxygen loss), reservoirs (18.6% loss), and oceans (2% loss) have all experienced oxygen loss since the 1980s, primarily driven by global warming and the addition of excess nutrients as a result of land use. A 2026 study by the same research team described the phenomenon with more urgency, suggesting global aquatic deoxygenation is pushing the planet toward an “unsafe space,” with resulting changes that could persist for centuries and might not be reversible within human lifetimes.

CONNECT THE DOTS

• In 2009, a group of internationally renowned scientists introduced the Planetary Boundaries framework, identifying nine environmental processes critical to maintaining a stable Earth that humans are pushing past their limits, including climate change, biodiversity loss, and chemical pollution (research suggests we’ve already crossed seven of the nine boundaries). The researchers behind the 2024 and 2026 studies have called for aquatic deoxygenation to be added as the 10th boundary, recognizing the trend as a global threat that’s closely connected to other major Earth systems. Thankfully, there’s reason for hope: a new study by researchers in China found targeted nutrient management via wastewater control can reverse freshwater deoxygenation.