Accelerating Acidification Threatens Coastal Ecosystems
New research from the University of St Andrews reveals a concerning trend: coastal seas are acidifying at a shockingly rapid pace. The study, published in Nature Communications, highlights that some coastal regions are on track to become far more acidic than scientists initially projected. This accelerated acidification poses a significant threat to coastal industries and the livelihoods of communities worldwide.
The fundamental driver of this phenomenon is the escalating levels of atmospheric CO2. As more carbon dioxide enters the atmosphere, it dissolves into the ocean at an alarming rate. This absorption process leads to a rapid decrease in the ocean's pH, making seawater progressively more acidic.
Upwelling Systems: A Key Amplifier
The research team focused on the California Current as a case study, uncovering that upwelling regions intensify ocean acidification rather than merely reflecting atmospheric trends. Upwelling occurs when deep ocean layers, already rich in nutrients and naturally acidic, rise toward the shore.
This process works as follows: organic material from surface waters sinks into the deep ocean, where microbes break it down. This microbial activity releases CO2, further increasing acidity in the deep waters. When these deep waters are brought back to the surface through upwelling, they deliver this accumulated acidity, compounding the effects of atmospheric CO2 absorption.
Historical Coral Records: A Window into the Past
To understand the long-term changes in coastal acidity, the researchers analyzed historical coral samples. By measuring boron isotope signatures preserved within the coral skeletons, they were able to reconstruct changes in coastal acidity throughout the 20th century. This historical data provided a crucial baseline for comparison with current trends.
The team then employed a regional ocean model to project how acidity is likely to evolve during the 21st century. The model's findings corroborated the alarming trend observed in the coral records, indicating that upwelling zones are experiencing acidification rates that significantly exceed those expected from atmospheric CO2 increases alone. This amplification effect is primarily due to the inherently acidic nature of upwelled water, which is further exacerbated by rising CO2 levels from human activities.
Implications for Fisheries and Global Stability
Upwelling systems are among the most biologically productive regions on Earth, playing a crucial role in sustaining global fisheries. Therefore, understanding how these systems respond to rising CO2 is vital for both ocean science and the long-term stability of the fisheries that depend on them. The accelerated acidification observed in these regions could have devastating consequences for marine ecosystems and the human populations that rely on them.
Dr. Hana Jurikova, Senior Research Fellow at the School of Earth and Environmental Science, emphasized the complexity of predicting how upwelling systems will respond to climate change. "Our research shows that such interactions can amplify environmental change in the California Current System, highlighting the need for similar studies in other regions to better anticipate future change," she stated.
A Global Challenge
The California Current serves as a stark warning, but it's only one piece of a larger puzzle. Other major upwelling systems, including the Humboldt Current off Peru and the Benguela and Canary Currents along the west coast of Africa, are also at risk of experiencing similar intensification of acidification as CO2 levels continue to rise. Addressing this global challenge requires a concerted effort to reduce CO2 emissions and mitigate the impacts of climate change.
Dr. James Rae, Reader in the School of Earth and Environmental Science, highlighted the urgency of the situation, stating, "The ocean becoming more acidic poses major risks to marine ecosystems and the communities and economies they support. The solutions we now have for climate change, like heat pumps and electric vehicles, also fix ocean acidification, so it's critical that we support them."
