The acidity level of the oceans has exceeded the threshold compatible with stable and sustainable ecosystems, warns the Potsdam Institute for Climate Research (PIK).
Thus, seven out of the nine „planetary boundaries” defined by scientists have been breached, reports AFP. The only thresholds remaining below the critical level are air pollution (atmospheric aerosols) and the ozone layer.
The concept of „planetary boundary” was formulated in 2009 by a group of around 30 researchers, who then estimated that humanity had exceeded at least three such thresholds. Since then, PIK’s annual assessments have shown a constant deterioration, and the 2025 edition confirms the breach of the limit related to ocean acidification.
„The ocean is on the verge of acidification, threatening marine life and putting us in dangerous conditions, with a worsening trend,” warn the authors of the report.
The main cause is the absorption of carbon dioxide (CO2) emitted from burning fossil fuels. Researchers estimate that the oceans have absorbed about 30% of the excess CO2 resulting from the burning of oil, natural gas, and coal.
Ocean acidity is measured by pH, but the reference indicator is the concentration of aragonite, an essential mineral for corals and marine organisms with shells. The limit was set at 80% of the pre-industrial level, and the oceans have dropped below this threshold. „The pH at the ocean surface has already decreased by 0.1 since the beginning of the industrial era. This is equivalent to a 30-40% increase in acidity,” note the researchers.
The effects are severe: „This change threatens organisms that form shells or skeletons from calcium carbonate, such as corals, mollusks, or crucial species of plankton. The gradual disappearance of these organisms can disrupt the food chain,” the report states.
### „Governments should listen to science”
The other already exceeded boundaries concern climate change, biodiversity loss, deforestation, the freshwater cycle, pollution with pesticides and fertilizers, as well as the introduction of new entities into the biosphere, such as plastic or industrial chemicals.
The report was presented on Wednesday in New York during the UN General Assembly. The director of PIK, Johan Rockström, was asked about the United States’ refusal to recognize the climate emergency. „Donald Trump has no credible scientist by his side. He has no support, not even among his climate-skeptic friends,” he said.
Colombian President Juan Manuel Santos emphasized: „We need governments to listen to science.” Former Irish President Mary Robinson added: „Imagine if every national budget, every security plan, every trade agreement started with the question: does this keep us within the planetary boundaries? This is the change we need.”
Oceans cover 70% of the Earth’s surface and contain 97% of the planet’s water – a vital resource increasingly threatened now.