A report published in the journal Nature suggests that global warming may increase upwelling in several ocean current systems around the world by the end of this century, especially at high latitudes, and will cause major changes in marine biodiversity. Since upwelling of colder, nutrient-rich water is a driving force behind marine productivity, one possibility may be enhancement of some of the world’s most important fisheries. However, solar heating due to greenhouse warming may also 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 to a significant extent, 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.
