A recent scientific study provides evidence that the Atlantic ocean conveyer belt is slowing. The data suggests that the Atlantic overturning circulation is 30% slower than that of the period between 1957 and 2004, although the direct impacts of climate change to the overturning circulation have yet to be documented through observations.
- Bryden, Harry L. et al. ”Slowing of the Atlantic meridional overturning circulation at 25° N.” Nature 438: 655-657. 1 December 2005 at www.nature.com
The analysis is part of a periodic sampling of ocean flows at 25 degrees N latitude. The most recent surveys, undertaken in 1998 and 2004 show notable decreases in deep circulation flow. The reduction in volume of the flow is huge: the equivalent of 60 times the flow of the Amazon River.
Implications: Global ocean circulation is one mechanism that regulates temperature throughout the world; warm waters around the equator flow northward and bring heat to Northern Europe, while cool waters from the polar region flow southward. Reductions in the volume of these flows are likely to yield a corresponding reduction in the northward heat flux. Should this be sustained, it would be extremely significant: modeling experiments suggest that this kind of decrease should be associated with a decrease in ocean temperatures in the NorthnAtlantic of up to 2 degrees Celsius or so, and maybe 0.5 degrees Celsius over Europe. While such changes have not yet been observed (both the North Atlantic and Europe have warmed over this time period), if the trend continues we may expect considerable changes in the temperature and climate of Europe.
