Global warming has already impacted not just the surface but also the depths of the World Ocean: significant climatic shifts have been recorded in a quarter of the upper thousand-meter strata. This conclusion was reached by an international group of researchers led by Tanya Zhetao from the Chinese Academy of Sciences. The study is published in the journal Nature Climate Change.
The investigators examined how four key ocean condition indicators—temperature, water pH, salinity, and dissolved oxygen content—changed from 1960 to 2023. Areas where at least two parameters varied simultaneously were categorized as zones of major climate impact.
It turned out that the pH has become more acidic across nearly the entire expanse of the World Ocean in recent decades. At a depth near 1000 meters, temperature increased while oxygen content decreased across 32% of the area—a combination extremely perilous for marine life. Even more concerning is the fact that three or more indicators simultaneously altered on 11% of the surface area.
Particularly hard-hit, according to the authors, were the Mediterranean Sea, where climatic influence affected 96% of its aquatic area, and the subtropical sector of the North Atlantic (93% of its surface). In these domains, ecosystems face pressure from multiple factors simultaneously: warming, acidification, and oxygen “depletion.”
The scientists emphasize that at depths up to 1000 meters, the climatic signal appears even more distinct than at the surface: there is less influence from seasonal variations and natural variability. By their estimation, if these trends persist, an increasing number of marine ecosystems will transition into a state of chronic strain, which raises the hazard of cascading failures and localized collapses of food webs.
About the Author
