The health of the planet is at a critical juncture, with a recent study revealing that six out of nine key environmental indicators are already in the red. Among these is ocean acidification, which is set to breach its planetary limit in the coming years.
The root of the problem lies in carbon emissions. Not only do they contribute to climate warming, the vast amounts of CO2 released into the atmosphere also destabilise the balance of the oceans.
About one-third of the CO2 produced by human activities has been absorbed by the oceans since the start of the industrial revolution.
Because CO2 is an acidic gas, this absorption leads to ocean acidification. The acidity of oceans has already increased by nearly 30 percent, and if lifestyle changes are not made, predictions suggest a further 150 percent rise in acidity by 2100.
Threatened marine life
Experts warn that the implications of acidification are severe for marine ecosystems. The chemical changes in the ocean disrupt the ability of marine organisms to build their shells and skeletons, as many rely on carbonate, which becomes increasingly soluble in more acidic conditions.
This trend threatens not only large marine life but also smaller organisms, such as plankton, that form the foundation of the ocean food web.
"Many microorganisms but also larger organisms like corals build their shells or skeletons from carbonate," said Wolfgang Lucht, a planetary systems specialist at the Potsdam Institute for Climate Impact Research, which co-authored the study.
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"In a more acidic ocean, the carbonate dissolves more easily, so they have much greater difficulties forming their bodies."
This phenomenon mirrors the effect of vinegar dissolving limestone, threatening not only oysters, crabs and sea urchins, but also vital microscopic plankton that form the backbone of marine ecosystems.
"This can create enormous disruptions throughout the entire ocean food chain, and we are now very close to the high-risk zone where these profound changes can occur," Lucht told RFI.
Nine planetary boundaries
Fifteen years ago, an international team of scientists defined nine planetary boundaries, which indicate thresholds beyond which natural balances can be destabilised.
A report from September 2023 reveals that six of these limits have already been crossed, including those related to climate change, biodiversity loss, and pollution from chemical fertilisers.
The ozone layer and fine atmospheric particles currently remain within safe limits, but the threshold for ocean acidification is projected to be crossed in just a few years.
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Boris Sakschewski, one of the lead authors of the Planetary Health Check – a yearly assessment produced by the Potsdam Institute – stressed the urgency of the situation.
"Polluting lifestyles have already led to excessive CO2 emissions, which accumulate in the atmosphere and eventually dissolve in the oceans. It will remain there for tens of thousands of years," he said.
"While it is difficult to predict the exact extent of the impact of this acidification, it is certain that it will not be trivial."
As the planet faces this pressing crisis, Lucht urged for immediate action to address the causes of these environmental threats.
"The best thing to do is to limit our emissions to prevent things from getting worse," he said.
This article was adapted from the original French version by RFI's Jeanne Richard.
