The world’s oceans have crossed a dangerous threshold for acidity, according to the latest Planetary Health Check by the Potsdam Institute for Climate Impact Research. Scientists say the rise in acidity, driven by fossil fuel emissions, now threatens marine ecosystems and food security.
Since the industrial era, ocean surface pH has dropped by about 0.1 units, a 30-40% increase in acidity. This reduces calcium carbonate, vital for corals, molluscs, and shell-building organisms. Cold-water corals, tropical reefs, and Arctic marine life are especially vulnerable. The disruption at the bottom of the food chain endangers species from oysters to whales, with serious consequences for human diets and coastal economies.
Oceans, covering 71% of Earth’s surface, regulate climate by absorbing heat and up to 30% of atmospheric carbon dioxide. But scientists warn that rising acidity could weaken this role, pushing the Earth further out of balance.
Ocean acidity is now the seventh of nine planetary boundaries breached, alongside climate change, biosphere integrity, land use, freshwater use, biogeochemical flows, and novel entities. The report describes this addition as especially alarming given the ocean’s global importance.
Researchers stress that reducing fossil fuel use, cutting pollution, and better fishery management could slow the damage. They point to past successes like the Montreal Protocol as evidence that international cooperation can reverse environmental decline.
Potsdam director Johan Rockström said: “Even if the diagnosis is dire, the window of cure is still open. Failure is not inevitable; failure is a choice.”
