Scientists Warn of Potential Ocean Crisis Similar to Past Extinctions

A recent study led by researchers from the University of St Andrews and the University of Birmingham has revealed alarming parallels between a prehistoric ocean crisis and today's rising atmospheric CO₂ levels. Approximately 201 million years ago, during the Triassic-Jurassic boundary, a significant increase in carbon dioxide led to dramatic ocean acidification that decimated marine life and caused a mass extinction. The findings, published in the journal Nature Communications on July 16, 2025, emphasize the need for immediate action to mitigate current trends that could replicate this catastrophic event.

The study marks the first comprehensive reconstruction of ancient ocean pH levels using boron isotopes extracted from fossilized oysters, which demonstrated a substantial drop in ocean acidity. According to Dr. James Rae, a co-author and researcher at the University of St Andrews, this pH decline, quantified at over 0.29 units, resulted from an estimated 10,000 gigatons of carbon released into the atmosphere, primarily attributed to volcanic activity linked to the breakup of the supercontinent Pangaea.

Historically, Earth’s oceans served as vibrant ecosystems, home to early modern corals, ichthyosaurs, and ammonites. However, the acidification triggered a prolonged period known as the 'reef gap,' lasting hundreds of thousands of years, during which many marine organisms struggled to form shells or skeletons. Dr. Sarah Greene, a co-author and marine biologist, warns that the rapid pace of contemporary ocean acidification could yield consequences more severe than those observed during the Triassic-Jurassic transition. 'The geological record tells us that major CO₂ releases transform marine ecosystems profoundly,' she stated, urging for intensified efforts to curb greenhouse gas emissions.

The researchers utilized the cGENIE Earth system model to simulate various carbon release scenarios, confirming that mantle-derived carbon was the most significant contributor to the acidification event. The findings were corroborated by data showing that carbonate saturation levels fell drastically, impacting marine life that thrived under high-saturation conditions.

Despite the devastating impacts of the past, the study indicates that ocean pH levels eventually rebounded due to the emergence of silica-producing organisms, which disrupted reverse weathering processes that had previously exacerbated high-CO₂ conditions. This historical perspective underscores the critical nature of ocean chemistry and the consequences of unchecked carbon emissions.

The implications of this study extend beyond academic inquiry; they serve as a stark reminder of the potential for contemporary climate change to evoke similar outcomes. The analysis points to the occurrence of ocean acidification in at least three of Earth’s five major mass extinction events, including the Permian–Triassic and Toarcian extinctions. The observed pH declines in these periods closely align with worst-case predictions for future scenarios outlined by the Intergovernmental Panel on Climate Change (IPCC).

In conclusion, the research highlights the urgent need for proactive measures to combat climate change and prevent the acidification of oceans from reaching levels that could mirror those in ancient extinction events. As Dr. Rae aptly put it, 'We have to act fast to avoid these outcomes in our future.' This study not only enriches our understanding of historical biological crises but also serves as a clarion call for immediate action in the face of ongoing environmental challenges.