|Slowing of the Atlantic meridional overturning circulation at 25° N|
Bryden, H.L.; Longworth, H.; Cunningham, S.A. (2005). Slowing of the Atlantic meridional overturning circulation at 25° N. Nature (Lond.) 438(7068): 655-657
In: Nature: International Weekly Journal of Science. Nature Publishing Group: London. ISSN 0028-0836, more
|Authors|| || Top |
- Bryden, H.L.
- Longworth, H.
- Cunningham, S.A.
The Atlantic meridional overturning circulation carries warm upper waters into far-northern latitudes and returns cold deep waters southward across the Equator1. Its heat transport makes a substantial contribution to the moderate climate of maritime and continental Europe, and any slowdown in the overturning circulation would have profound implications for climate change. A transatlantic section along latitude 258N has been used as a baseline for estimating the overturning circulation and associated heat transport 2-4. Here we analyse a new 258N transatlantic section and compare it with four previous sections taken over the past five decades. The comparison suggests that the Atlantic meridional overturning circulation has slowed by about 30 percent between 1957 and 2004. Whereas the northward transport in the Gulf Stream across 258N has remained nearly constant, the slowing is evident both in a 50 per cent larger southward-moving mid-ocean recirculation of thermocline waters, and also in a 50 percent decrease in the southward transport of lower NorthAtlantic Deep Water between 3,000 and 5,000m in depth. In 2004, more of the northward Gulf Stream flow was recirculating back southward in the thermocline within the subtropical gyre, and less was returning southward at depth.