A new study warns that global warming may increase upwelling in several ocean current systems around the world by the end of this century, especially at high latitudes, causing major changes in marine biodiversity.
Bruce Menge, the Wayne and Gladys Valley Professor of Marine Biology in the College of Science, co-authored the report published this week’s issue of the journal Nature.
Solar heating due to greenhouse warming may increase the persistence of “stratification,” or the horizontal layering of ocean water of different temperatures. The result could be a warm, near-surface layer and a deep, cold layer.
If this happens extensively, it could increase global “hypoxic,” or low-oxygen events, decouple upwelling from the supply of nutrient-rich water and pose a significant threat to the global function of fisheries and marine ecosystems. This projected increase in upwelling is clear and definitive.
But researchers say its biological impact is far less obvious, which is a significant concern.
“Our modeling indicates that normally weaker upwelling toward the polar ends of upwelling-dominated regions will strengthen,” said Menge.
These upwelling systems cover less than 2% of the ocean surface, but contribute 7% to global marine primary production, and 20% of global fish catches.
“Ordinarily, you would expect that an increase in upwelling would mean an increase in marine coastal productivity, and that might happen,” Menge said. “However, a thicker and warmer top later, and more stratified ocean waters may put the cold, nutrient-rich waters too deep for upwelling to bring them up, and reduce the ability of upwelling to energize the coastal ocean food web,” he said.
“This could have a very negative impact on marine production and fisheries.”
The findings were made by researchers from OSU and Northeastern University, in work supported by that university and the National Science Foundation.