Southern Ocean resistant to changing winds

Dec 08, 2008

Intensifying winds in the Southern Ocean have had little influence on the strength of the Southern Ocean circulation and therefore its ability to absorb carbon dioxide from the atmosphere, according to a study published in Nature Geoscience.

The Southern Ocean slows the rate of greenhouse warming by removing carbon dioxide from the atmosphere and storing it in the ocean. But previous studies raised the alarm by suggesting the Southern Ocean carbon sink is now 'saturated' and no longer able to keep pace with increasing concentrations of carbon dioxide in the atmosphere.

The new study suggests that Southern Ocean currents, and therefore the Southern Ocean's ability to soak up carbon dioxide, have not changed in recent decades, despite a large increase in winds.

A team of German and Australian scientists compared new ocean measurements from a global network of ocean robots with historical data from ships to determine if the Southern Ocean was changing. The study was led by Professor Claus Böning from the Institute of Marine Research (IFM-GEOMAR), Kiel.

Co-author, CSIRO's Dr Steve Rintoul, says the Southern Ocean was found to have become warmer and fresher since the 1960s – a pattern consistent with the 'fingerprint' of climate change caused by carbon emissions from human activity.

"But, counter to our expectations, other aspects of the Southern Ocean have not changed despite the increase in winds," he says. "In particular, we found no evidence of a change in strength of the ocean currents that circle around Antarctica, or in the amount of deep water rising to the surface near Antarctica."
The fact that the upwelling of deep water has not changed is important. Deep water is very rich in carbon dioxide and so an increase in upwelling tends to transfer carbon dioxide from the ocean to the atmosphere. The low-resolution models used for climate forecasts predict stronger winds, which cause stronger upwelling and therefore less carbon dioxide being stored in the ocean.

"Our results suggest that the small-scale motions of ocean eddies act to balance the stronger winds, with no change in upwelling," Dr Rintoul says. "Climate models in use today cannot represent these small-scale motions and so over-estimate the response of the Southern Ocean to changes in winds." Dr Rintoul works through the Antarctic Climate and Ecosystem Cooperative Research Centre (ACECRC) and CSIRO's Wealth from Oceans Flagship.

Integral to the research was the Australian ocean data archive and the Argo network of ocean profilers. The data provided by the global array of more than 3,100 Argo floats is particularly valuable in remote areas like the sparsely-sampled Southern Ocean.

Source: CSIRO Australia

Explore further: NASA's HS3 mission continues with flights over Hurricane Gonzalo

add to favorites email to friend print save as pdf

Related Stories

Monitoring carbon movement

Oct 10, 2014

Studying the movement of carbon dioxide into the deep ocean to improve climate projections and understanding of deep-sea ecosystems will be the focus of a two-year research project by a University of Maine ...

Arctic sea ice helps remove CO2 from the atmosphere

Sep 22, 2014

Climate change is a fact, and most of the warming is caused by human activity. The Arctic is now so warm that the extent of sea ice has decreased by about 30 pct. in summer and in winter, sea ice is getting ...

Coral growth rate plummets in 30-year comparison

Sep 17, 2014

A team of researchers working on a Carnegie expedition in Australia's Great Barrier Reef has documented that coral growth rates have plummeted 40% since the mid-1970s. The scientists suggest that ocean acidification ...

Recommended for you

NASA image: Fires in the Egypt River Delta

13 hours ago

This NASA satellite image is of the Egyptian River Delta. Actively burning areas, detected by MODIS's thermal bands, are outlined in red. Each hot spot, which appears as a red mark, is an area where the thermal ...

Terra Satellite sees Tropical Storm Ana over Hawaii

13 hours ago

Tropical Storm Ana made a slow track west of the Hawaiian islands over the last couple of days, and by Oct. 20 was moving westward away from the main Hawaiian islands and heading toward the northwest Hawaiian ...

User comments : 5

Adjust slider to filter visible comments by rank

Display comments: newest first

wfl
4 / 5 (2) Dec 09, 2008
Another nail in the AGWers coffin. The remaining question is how many more nails are required to permanently seal it.
Velanarris
5 / 5 (1) Dec 09, 2008
Another nail in the AGWers coffin. The remaining question is how many more nails are required to permanently seal it.


AGW is still a valid hypothesis.

Key word being hypothesis. The declaration of AGW as fact is the problem.
MikPetter
1.5 / 5 (2) Dec 10, 2008
actually the paper says "Co-author, CSIRO's Dr Steve Rintoul, says the Southern Ocean was found to have become warmer and fresher since the 1960s %u2013 a pattern consistent with the 'fingerprint' of climate change caused by carbon emissions from human activity."

I guess prejudice can cause some people to fail to read what is actually written....
mikiwud
5 / 5 (1) Dec 10, 2008
MikPetter,
I think that is the mandatory insert in order to get the funding. It is the first time I have heard it as a "fingerprint".The tropical upper troposphere heating finger print is missing,so,is this the "new" one?
Velanarris
5 / 5 (1) Dec 10, 2008
actually the paper says "Co-author, CSIRO's Dr Steve Rintoul, says the Southern Ocean was found to have become warmer and fresher since the 1960s %u2013 a pattern consistent with the 'fingerprint' of climate change caused by carbon emissions from human activity."

I guess prejudice can cause some people to fail to read what is actually written....
I think that works both ways, seeing as the dispute was over the predictions of the AGW theorists, not the related effect on oceanic observations.

Perhaps your bias is also seeing things that aren't there.