Draft:Ocean currents and climate change

Ocean currents and climate change
As atmospheric temperatures continue to rise, this is anticipated to have various effects on the strength of surface ocean currents, wind-driven circulation and dispersal patterns. Ocean currents play a significant role in influencing climate, and shifts in climate, in turn, impact ocean currents. Over the last century, reconstructed sea surface temperature data reveal that the western boundary currents are warming at twice the rate of the global average. These observations indicate that the western boundary currents are likely intensifying due to this change in temperature, and may continue to grow stronger in the near future. Studies investigating international ocean current patterns have also suspected that anthropogenic climate change has accelerated upper ocean currents by 77%. Faster upper ocean currents are often associated with increased vertical stratification, as well as faster and stronger zonal currents.

In addition to water surface temperatures, the wind systems are a crucial determinant of ocean currents. Wind wave systems control oceanic heat exchange, the condition of the sea surface, and can alter ocean currents. In the North Atlantic, equatorial Pacific, and Southern Ocean, increased wind speeds as well as significant wave heights have been attributed to climate change and natural processes combined. In the East Australian Current, global warming has also been accredited to increased wind stress curls, which intensify these currents, and may even indirectly increase sea levels, due to the additional warming created by stronger currents.

As ocean circulation changes due to climate, typical distribution patterns are also changing. The dispersal patterns of marine organisms depend on oceanographic conditions, which as a result, influence the biological composition of oceans. Due to the patchiness of the natural ecological world, dispersal is a species survival mechanism for various organisms. With boundary currents moving toward the poles, it is expected that some marine species will be redirected to the poles and greater depths. The strengthening or weakening of typical dispersal pathways by increased temperatures are expected to not only impact the survival of native marine species due to inability to replenish their meta populations but also may increase the prevalence of invasive species. In Japanese corals and macroalgae, the unusual strengthened dispersal pattern of organisms toward the poles may destabilize native species.