We Might Be Solving One Planetary Boundary by Quietly Stressing Another In 2009, Johan Rockström and the Stockholm Resilience Centre defined Nine Planetary Boundaries — the "safe operating space" within which human civilization can keep enjoying the stable Holocene conditions it evolved in: 1)climate change, 2)biosphere integrity, 3)land system change, 4)freshwater change, 5)biogeochemical flows, 6)novel entities, 7)ocean acidification, 8)stratospheric ozone depletion, and 9)atmospheric aerosol loading. Seven of the nine have already been crossed . 🌊 A 10th boundary is now on the table: Aquatic Deoxygenation . Dissolved oxygen in lakes, rivers, and coastal waters is falling — driven by two compounding forces: warmer water simply holds less oxygen, and nutrient runoff (nitrogen and phosphorus) fuels algal blooms that consume oxygen as they decompose. The result is expanding dead zones, biodiversity collapse, and — less obviously — the release of potent greenhouse g...