The study, published recently in the journal Nature Geoscience, was conducted jointly by researchers from Peking University, Pennsylvania State University, the University of California at Riverside and other institutes.
The team reconstructed the state of ocean acidification during the Paleocene-Eocene Thermal Maximum (PETM), a climatic event characterized by significant increases in global temperatures and severe ecosystem disruptions. The study found striking parallels between ocean acidification during the PETM and current trends caused by rising atmospheric carbon dioxide.
During the PETM, the sharp increase in carbon emissions led to a sharp decrease in ocean pH, which reduced the availability of carbonate ions needed by marine organisms to form shells, a critical component of ocean carbon storage.
Using paleoclimate data assimilation that combines proxy records with simulations of Earth system models, the researchers reconstructed changes in the chemical composition of carbonates in the ocean. They calculated that atmospheric carbon dioxide levels rose from 890 parts per million (ppm) to 1980 ppm during the PETM, which was accompanied by an average decrease in ocean pH of 0.46 units.
“These findings are a clear warning for the future,” said Li Mingsong, a professor at Peking University, adding that the drop in ocean pH during the PETM closely resembles modern predictions under high-emission scenarios.
Li noted that the current rate of carbon emissions is much faster than during the PETM, posing a serious threat to marine ecosystems and biodiversity.
“The PETM, which lasted about 200,000 years, represents a natural analogue of what uncontrolled carbon emissions can cause today. The accelerated emissions we face today pose an even greater, long-term threat to marine life, especially in vulnerable regions like the Arctic,” Li added.
According to the researchers, the findings underscore the lasting consequences of increased carbon emissions and highlight the urgent need for climate action to protect ocean health and global biodiversity. | BGNES
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