Climate Change in the Arctic - The Changing Arctic Environment: The Arctic Messenger - page 237

that the North Atlantic's contribution to deep water is about 17 sverdrups (Sv). 5 For the
Antarctic, the contribution to bottom water is given as 15 Sv, although studies using chlo-
rofluorocarbon (CFC) as a tracer gave an estimate as low as 5 Sv. These are the only areas
in the world where the surface waters are subject to sufficiently intense cold temperatures,
coupled with salt rejection from the creation of sea ice, to manufacture huge quantities
of heavy (high density) cold and saline water. The deep waters formed in the Arctic and
Antarctic flow towards the equator. The Atlantic deep water penetrates far into the South-
ern Hemisphere. The movement of surface waters to depth in the Arctic and Antarctic is
called meridional overturning and is an example of thermohaline circulation. Without me-
ridional overturning, the ocean's capacity toefficiently transport CO 2 andheat fromsurface
waters to the deep would be dramatically reduced. (See Figure 10.4 .)
Figure 10.4
Global thermohaline circulation and meridional overturning