New Research Supports Power Of Ocean Currents In Climate - Science Daily

[hatrack]

"A paper published this week in the journal Science supports the hypothesis that heat transfer by ocean currents – rather than global heating or cooling – may have been responsible for the global temperature patterns associated with the abrupt climate changes seen in the North Atlantic during the past 80,000 years.

Authored by the University of Bremen's Frank Lamy and colleagues, the paper provides new evidence that Southern Hemisphere climate may not have changed in step with Northern Hemisphere climate. Though these new measurements of ocean surface temperature off Chile are consistent with information from Antarctic ice core samples, they still contradict measurements made on land in the Southern Hemisphere – suggesting additional research will be needed to resolve the issue.

Scientists have found evidence of rapid and dramatic climate change that took place in a matter of decades during cool periods of the last 80,000 years in the North Atlantic. Knowing whether climate changes took place simultaneously in the Northern and Southern Hemispheres is vital to understanding the mechanism involved – and assessing whether similar abrupt climate change could be a threat today.

EDIT

"The real significance of this paper is that it gets us closer to understanding the mechanism causing these rapid climate changes," she said. "Earlier sediment core work at lower resolution has suggested that the Southern Hemisphere has been doing its own thing. The record from Antarctica is nicely resolved and shows that the Southern Hemisphere is not participating either in magnitude or timing with the climate changes that have occurred in the North Atlantic." The Lamy researchers studied sediment cores taken from a location off the coast of southern Chile where sediment builds up rapidly, providing detailed information about climate change with good time resolution. Their 50,000-year record is consistent with Antarctic ice core data showing that Southern Hemisphere climate change did not occur at the same or in the same magnitude as Northern Hemisphere change. "What this paper suggests is that that when it was really cold off Greenland in the North Atlantic, it was actually a bit warm off Chile," said Lynch-Stieglitz. "That's very similar to the record in Antarctica. The fact that the ocean off Chile looks so much like what has been going on in Antarctica gives us hope that there may be a consistent response throughout the Southern Hemisphere."

EDIT

http://www.sciencedaily.com/releases/2004/06/040625090130.htm

[LastDemocratInSC]

1. The primary factor in varying arctic currents is icemelt

... and icemelt is primarily caused by increasingly warmer atmospheric temperatures which are, in turn, primary caused by increasingly higher levels of carbon dioxide in the atmosphere.

The fresh water of melting icepacks dilutes the salinity of the ocean so that it is less dense. Enough fresh water can cause the vertically falling currents to stop which, of course, stops the transfer of heat energy from north to south. The mini-iceage in Europe in the early 1300s may have been caused by this. A prolonged period of warmer air temps results in a sudden cold-snap that lasts for years to decades.

It's impossible to separate the dynamics of the atmosphere from those of the oceans. Global atmospheric warming is a fact, and the increasing ice melt, especially in Greenland and the Arctic Ocean will have a dramatic effect on events in time.

[Dogmudgeon]

2. The scary part of this

The icemelt from Greenland has been speeding up dramatically, and no one has been able to figure out why. As recently as 2002, the general consensus seemed to be that it would take around a thousand years to denude Greenland of ice. Now, many scientists think that will happen by mid-century.

Even during the last interstadial period (the warm period between ice ages), Greenland had a substantial ice pack.

--bkl

[Oggy]

3. Do you have a reference

I can access for the claim "many scientists think that will happen by mid-century"?

I have been looking at this issue when I've had time over the last couple of months, and I hadn't seen this claim, only that there was insufficent data, and that there were some studies being done at the moment. I would be very intrested if you have anything backing this up.

Thanks.