More than three-quarters of planet Earth’s life support systems are no longer in the safe zone, experts warn.
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Humans are pushing the planet “beyond the limits of a safe operating space” as yet another critical Earth system boundary has been breached.
A damning new report reveals the planet’s ocean acidification - where the water’s pH is lowered due to CO₂ absorption - has entered the danger zone for the first time ever.
The 2025 Planetary Health Check, published by the Planetary Boundaries Science Lab at the Potsdam Institute for Climate Impact Research (PIK), warns that seven of the nine critical Earth system boundaries have now been breached, one more than last year.
The institution blames the “stark new development” on fossil fuel burning, deforestation and land-use change, arguing the trifecta is degrading the ocean’s ability to “act as Earth’s stabiliser".
Why are the oceans so important?
“The ocean is becoming more acidic, oxygen levels are dropping and marine heatwaves are increasing,” says Levke Caesar, co-lead of Planetary Boundaries Science Lab, and one of the authors of the report.
“This is ramping up pressure on a system vital to stabilise conditions on planet Earth. This intensifying acidification stems primarily from fossil fuel emissions, and together with warming and deoxygenation affects everything from coastal fisheries to the open ocean.”
Caesar adds that the consequences of the ocean’s acidification will “ripple outward”, impacting issues including food insecurity, global climate stability and human wellbeing.
Since the start of the industrial era, the pH of the ocean’s surface has dropped by around 0.1 units, a 30 to 40 per cent spike in acidity. This has already resulted in pteropods (tiny sea snails) showing signs of shell damage.
While this may not seem significant, they’re a crucial food source for many species, and experts say their decline can impact entire food chains.
“The ocean is our planet’s life-support system,” says Dr Sylvia Earle, a renowned oceanographer and Planetary Guardian. “Without healthy seas, there is no healthy planet.
“For billions of years, the ocean has been Earth’s great stabiliser: generating oxygen, shaping climate, and supporting the diversity of life. Today, acidification is a flashing red warning light on the dashboard of Earth’s stability. Ignore it, and we risk collapsing the very foundation of our living world. Protect the ocean, and we protect ourselves.”
Planetary Boundaries: What are they and which have been breached?
Planetary Boundaries Science launched in 2023 to address critical gaps in our understanding and monitoring of the Earth’s system. It coined nine boundaries that must remain within safe limits to “keep humanity safe and the natural world resilient”.
Scientists monitor these boundaries - similar to a health check at the doctor’s - to track the planet’s condition.
They include: Climate Change (a long-term shift in Earth’s temperature and weather patterns), Biosphere Integrity (the overall health, functioning and resilience of Earth’s living systems), Land System Change (from human-driven activities such as agriculture), Freshwater Use, Biogeochemical Flows, Novel Entities (like synthetic chemicals or microplastics), Ocean Acidification, Ozone Depletion (thinning of the Earth’s protective layer) and Aerosol Loading (air pollution).
Following the latest report, only two boundaries remain within safe boundaries: loading of aerosols and the stratospheric ozone layer.
“We are witnessing widespread decline in the health of our planet. But this is not an inevitable outcome,” states Johan Rockström, director of the Potsdam Institute for Climate Impact Research.
“The drop in aerosol pollution and healing of the ozone layer show that it is possible to turn the direction of global development. Even if the diagnosis is dire, the window of cure is still open. Failure is not inevitable; failure is a choice. A choice that must and can be avoided.”
