Coastal Seas Face Rapid Acidification Threats from Upwelling

New research from the University of St Andrews reveals alarming rates of acidification in coastal seas, particularly in upwelling regions like the California Current. Published in Nature Communications on November 13th, the study found that these areas are becoming far more acidic than previously thought, posing serious threats to marine ecosystems and coastal industries. As atmospheric CO2 levels rise, more of this gas dissolves into the ocean, driving a rapid drop in pH and increasing acidity.

Upwelling occurs when nutrient-rich waters from the ocean's depths rise to the surface, bringing with them accumulated CO2 that has been released by microbial breakdown of organic material. This process intensifies the natural acidity of the upwelled waters, which, when combined with atmospheric CO2, results in a significant increase in acidity. By analyzing historic coral samples and their boron isotope signatures, the researchers reconstructed changes in coastal acidity over the 20th century and used a regional ocean model to forecast future shifts in these patterns through the 21st century.

The findings indicate that the acidification rates in upwelling zones exceed those expected from atmospheric CO2 alone. Dr. Hana Jurikova, a Senior Research Fellow in the School of Earth and Environmental Science, emphasized the complexity of predicting how these systems will respond to climate change and the necessity for similar studies in other regions to anticipate future changes.

The implications of this research extend far beyond environmental concerns, as upwelling systems are crucial to global fisheries and the economies that depend on them. The California Current, for instance, contributes significantly to marine biodiversity and fisheries productivity. Other upwelling regions, such as the Humboldt Current off Peru and the Benguela and Canary Currents along the west coast of Africa, are likely to experience similar intensification of acidification. Dr. James Rae, a Reader in the School of Earth and Environmental Science, warned that the ocean’s increasing acidity poses major risks to marine ecosystems and the communities that rely on them.

He stated that solutions for climate change, such as heat pumps and electric vehicles, can also help mitigate ocean acidification, underscoring the critical need for their support. This research highlights an urgent call for conservation efforts and further investigations into the impacts of ocean acidification, as the health of marine ecosystems hangs in the balance.