Acid rain is passe; we have now created acid oceans, warns new report on planetary safety

A new report from the Planetary Boundaries Science Lab at the Potsdam Institute for Climate Impact Research (PIK) reveals alarming findings about the state of the Earth’s critical boundaries.

According to the 2025 Planetary Health Check, seven out of nine Earth system boundaries have now been breached — one more than the previous year. This raises significant concerns about the future stability of the planet and the increasing risk of irreversible environmental changes.

“More than three-quarters of the Earth’s support systems are not in the safe zone. Humanity is pushing beyond the limits of a safe operating space, increasing the risk of destabilising the planet,” said PIK director Johan Rockström.

The seven breached boundaries include:

• climate change,

• biosphere integrity,

• land system change,

• freshwater use,

• biogeochemical flows,

• novel entities, and

• ocean acidification.

All of these areas are showing worsening trends, signalling a dangerous trajectory for global ecosystems.

Seventh boundary breached

Among these breaches, ocean acidification stands out as the most recent cause for concern.

The 2025 report reveals that this boundary has been breached for the first time — a shift driven largely by fossil fuel burning, deforestation and land-use changes. This marks the seventh boundary transgressed, further pushing humanity beyond the safe zone for civilisation.

Ocean acidification is already having visible effects on marine life. Cold-water corals, tropical reefs and Arctic marine ecosystems are at particular risk, as acidity continues to rise in oceans.

Since the industrial era, the ocean’s surface pH has dropped by around 0.1 units — a 30-40 per cent increase in acidity.

This change is significantly altering marine ecosystems, with some species already showing signs of distress.

Tiny sea snails, called pteropods, which are an essential food source for various marine species, are experiencing shell damage. This decline could have far-reaching consequences for entire food chains, fisheries and ultimately human livelihoods.

Earth's stabiliser under threat

Levke Caesar, co-lead of the Planetary Boundaries Science Lab, commented on the gravity of the situation: “The movement we’re seeing is absolutely headed in the wrong direction. The ocean is becoming more acidic, oxygen levels are dropping, and marine heatwaves are increasing. This is ramping up pressure on a system vital to stabilise conditions on planet Earth.”

Dr Sylvia Earle, renowned oceanographer and Planetary Guardian, added, “The Ocean is our planet’s life-support system. 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.”

The report highlights that the nine planetary boundaries represent Earth’s operating system, the interconnected life-support processes that must stay within safe limits to preserve both human and ecological health.

Scientists monitor these boundaries, similar to vital signs in a health check, to gauge the planet’s wellbeing. The findings indicate accelerating deterioration and a growing risk of irreversible environmental change.

Boris Sakschewski, co-lead of the Planetary Boundaries Science Lab, explained, “The interconnections between the planetary boundaries show how a planet under pressure both locally and globally can impact everyone, everywhere. Securing human wellbeing, economic development, and stable societies requires a holistic approach, with collaboration across all sectors.”

Hope through global cooperation and policy action

While the report paints a grim picture of Earth’s current state, it also underscores that positive change is possible. Two boundaries — the loading of aerosols (air pollution) and the stratospheric ozone layer — remain within safe limits, thanks to decades of international cooperation and policy action. The success of measures like the Montreal Protocol, which phased out ozone-depleting chemicals, proves that coordinated action can make a significant difference in reversing environmental damage.

PIK director Johan Rockström emphasised, “We are witnessing widespread decline in the health of our planet. But this is not an inevitable outcome. The drop in aerosol pollution and the healing of the ozone layer shows that it is possible to turn the direction of global development.”

A call to action from climate scientists

The report also featured reactions from climate experts, urging immediate action to protect Earth’s ecosystems.

JM Santos, co-vice chair of the Planetary Guardians, called the breach of the ocean acidification boundary “a stark scientific warning and a moral call to action”. He urged global cooperation to safeguard this life-support system for future generations.

Additonally, Paul Polman, co-vice chair of the Planetary Guardians, echoed the sentiment: “Crossing the ocean boundary underlines the fragility of our global economy and the urgency of change. Business, governments, and civil society cannot afford delay.”

Meanwhile, Hindou Oumarou Ibrahim, chair of the Planetary Guardians, emphasised the importance of combining science with traditional knowledge to heal the planet.

“Indigenous peoples have safeguarded forests, water and biodiversity by living within nature’s limits. Today, the planetary boundaries science confirms what indigenous peoples have always known: when we push beyond these limits, we put all life at risk," he has been quoted as saying.a