Changing Antarctic winds create new sea level threat

Jul 07, 2014
Changing Antarctic winds create new sea level threat

New research shows projected changes in the winds circling the Antarctic may accelerate global sea level rise significantly more than previously estimated.

Changes to Antarctic winds have already been linked to southern Australia's drying climate but now it appears they may also have a profound impact on warming ocean temperatures under the ice shelves along the coastline of West and East Antarctic.

"When we included projected Antarctic wind shifts in a detailed global ocean model, we found water up to 4°C warmer than current temperatures rose up to meet the base of the Antarctic ice shelves," said lead author Dr Paul Spence from the ARC Centre of Excellence for Climate System Science (ARCCSS).

"The sub-surface warming revealed in this research is on average twice as large as previously estimated with almost all of coastal Antarctica affected. This relatively warm water provides a huge reservoir of melt potential right near the grounding lines of ice shelves around Antarctica. It could lead to a massive increase in the rate of ice sheet melt, with direct consequences for global ."

Prior to this research by Dr Spence and colleagues from Australian National University, the University of New South Wales, most sea level rise studies focused on the rate of ice shelf melting due to the general warming of the ocean over large areas.

Using super computers at Australia's National Computational Infrastructure (NCI) Facility the researchers were able to examine the impacts of changing winds on currents down to 700m around the coastline in greater detail than ever before.

Previous global models did not adequately capture these currents and the structure of water temperatures at these depths. Unexpectedly, this more detailed approach suggests changes in Antarctic coastal winds due to climate change and their impact on coastal currents could be even more important on melting of the than the broader warming of the ocean.

"When we first saw the results it was quite a shock. It was one of the few cases where I hoped the science was wrong," Dr Spence said.

"But the processes at play are quite simple, and well-resolved by the ocean model, so this has important implications for climate and sea-level projections. What is particularly concerning is how easy it is for climate change to increase the water temperatures beside Antarctic ice sheets."

The research may help to explain a number of sudden and unexplained increases in global sea levels that occurred in the geological past.

"It is very plausible that the mechanism revealed by this research will push parts of the West Antarctic Ice Sheet beyond a point of no return," said Dr Axel Timmerman, Prof of Oceanography at University of Hawaii and an IPCC lead author who has seen the paper.

"This work suggests the Antarctic ice sheets may be less stable to future than previously assumed."

Recent estimates suggest the West Antarctic Ice Sheet alone could contribute 3.3 metres to long-term rise.

With both West and East Antarctica affected by the change in currents, in the future abrupt rises in sea level become more likely.

According to another of the paper's authors, Dr Nicolas Jourdain from ARCCSS, the mechanism that leads to rapid melting may be having an impact on the Western Antarctic right now. Dr Jourdain said it may help explain why the melt rate of some of the glaciers in that region are accelerating more than scientists expected.

"Our research indicates that as global warming continues, parts of East Antarctica will also be affected by these wind-induced changes in ocean currents and temperatures," Dr Jourdain said.

"Dramatic rises in are almost inevitable if we continue to emit greenhouse gases at the current rate."

Explore further: How wind helps Antarctic sea ice grow, even as the Arctic melts

More information: Rapid subsurface warming and circulation changes of Antarctic coastal waters by poleward shifting winds, Geophysical Research Letters, DOI: 10.1002/2014GL060613 , http://onlinelibrary.wiley.com/doi/10.1002/2014GL060613/abstract

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User comments : 12

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verkle
1.7 / 5 (22) Jul 07, 2014
Another GW boohoo article. "Better act now or else!" One problem with the premise of this specific article is that Antarctic ice cover is getting greater, not less.

Please come up with a model that can accurately explain all of the climate patterns of the past, and then I will believe it for the future. Until then, I put zero expectations on each of these new theories that pop up daily. Just a dreadful waste of time.

runrig
4.2 / 5 (20) Jul 07, 2014
mr verkle:
The Antarctic (sea) ice is increasing (in extent) precisely because of the increasing winds in the SH, blowing it further out to sea and compacting it, and because increased melting of shelf-ice is freshening the ocean surface water.

I put zero expectation on your or your fellow deniers from seeing the science involved before reflexively shouting foul. Yes, correct, you are a dreadful waste of time.
Vietvet
4.2 / 5 (17) Jul 07, 2014
mr verkle:
The Antarctic (sea) ice is increasing (in extent) precisely because of the increasing winds in the SH, blowing it further out to sea and compacting it, and because increased melting of shelf-ice is freshening the ocean surface water.

I put zero expectation on your or your fellow deniers from seeing the science involved before reflexively shouting foul. Yes, correct, you are a dreadful waste of time.


You deserve ten stars.
Dr_toad
Jul 07, 2014
This comment has been removed by a moderator.
thermodynamics
4.1 / 5 (15) Jul 07, 2014
DT, Run, and VV: Exactly right, but don't leave out poor Ubamoron and her Woodfortrees plot or Cantdrive85 and the EU conspiracy. We seem to have a good share of the woo-woo crowd.
Steve Case
1.9 / 5 (15) Jul 07, 2014
http://www.utahpe...nt-16731

"Recent estimates suggest the West Antarctic Ice Sheet alone could contribute 3.3 metres to long-term global sea level rise."

Long-term isn't defined, but this story has been running elsewhere on the net this morning, and those stories said 200 - 300 years. So, 3.3 meters in 200 years comes to well over 16 mm/yr or around five times the current rate, and current rates are not going up faster and faster. If anything they've slowed a little. When do Dr.Timmerman and Dr. Jourdain say this dramatic change is going to begin happen?

With a little curiosity and some modest Excel skills anyone can Google Colorado Sea Level Research Group where there's a link to sea level data and verify that the rate of sea level rise is not increasing.

Steve Case – Milwaukee, WI
antigoracle
1.5 / 5 (16) Jul 07, 2014
You deserve ten stars.
-- vietvet
Because that's the highest you can count.
thermodynamics
4.4 / 5 (14) Jul 07, 2014
SC said:
With a little curiosity and some modest Excel skills anyone can Google Colorado Sea Level Research Group where there's a link to sea level data and verify that the rate of sea level rise is not increasing.


Which is the reason that people have to develop models and run them on a supercomputer. Excel and modest skills don't cut it when you are modeling the response of the earth.

Are you saying that you have a reliable model of sealevel in Excel that you think is better than the models that are being built?
runrig
4.7 / 5 (12) Jul 07, 2014
"Heavy rains from the Amazon to Australia have curbed SL rise so far this century by shifting water from the oceans to land, according to a study that rejects theories that the slowdown is tied to a pause in global warming."
"Writing in the journal Nature Climate Change on Sunday, experts said the rate from 2003-2011 would have been 3.3 mm a year when excluding natural shifts led by an unusually high number of La Nina weather events that cool the surface of the Pacific Ocean and cause more rain over land."
"There is no slowing in the rate of SL rise" after accounting for natural variations, lead author Anny Cazenave of the Laboratory for Studies in Geophysics and Spatial Oceanography in Toulouse, France said.
In La Nina years, more rain fell away from oceans, including over the Amazon, the Congo basin and Australia, she said. It is unclear if climate change itself affects the frequency of La Ninas."
http://www.reuter...20140323
MikPetter
4.6 / 5 (10) Jul 07, 2014
BTW for those interested in peer reviewed facts
Antarctica overall has accelerating ice loss... see article below
http://www.scienc...13005797
Earth and Planetary Science Letters,Volume 385, 1 January 2014, Pages 12–21
'"Revisiting GRACE Antarctic ice mass trends and accelerations considering autocorrelation"
"Despite the higher uncertainties, we find significant (2-sigma) accelerations over much of West Antarctica (overall increasing mass loss) and Dronning Maud Land (increasing mass gain) as well as a marginally significant acceleration for the ice sheet as a whole (increasing mass loss)."
antigoracle
1 / 5 (7) Jul 12, 2014
West Antarctica is melting due to geothermal activity.
So, what's your point.
runrig
5 / 5 (3) Jul 13, 2014
West Antarctica is melting due to geothermal activity.
So, what's your point.

Actually Thwaites glacier - just a small part of the WAIS.
And in your dreams ryggy ... There is only a contribution to melting.

Your point is to constantly misunderstand/misrepresent the science ... This when you're not off on one regarding "socialism".
antigoracle
1 / 5 (3) Jul 13, 2014
runrig, you just keep on repeating the deceit of your cult.
For years they blamed it all on man made CO2.
http://mashable.c...erating/
For some strange reason CO2 is only affecting the west Antarctic, exactly where geothermal activity is melting the ice.

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