Antarctic Sea Ice Extent

[CoastalWx]

So no real significant warming over the Antartic region, yet melting glaciers helping to freshen waters around the region? 

[FloridaJohn]

So no real significant warming over the Antartic region, yet melting glaciers helping to freshen waters around the region? 

 

Are you saying that glaciers are not melting in Antarctica?

[CoastalWx]

Are you saying that glaciers are not melting in Antarctica?

 

I'm asking what is going on exactly. Otherwise I don't really care.

[chubbs]

It is still too cold in Antarctica for ice sheet melting. My understanding is that warming ocean waters have weakened the floating ice shelves that are holding back key glaciers allowing a significant increase in glacier flow. The Western Antarctic Ice Sheet is grounded below sea level and is therefore unstable. Papers published earlier this year indicated that this ice sheet was already in the early stages of disintegration. Note that it wasn't too long ago that Antarctica was thought to be stable to AGW impacts

[The_Global_Warmer]

Antarctica is losing land ice mass. 

 

 

 

 

 

[CoastalWx]

It is still too cold in Antarctica for ice sheet melting. My understanding is that warming ocean waters have weakened the ice shelves that are holding back key glaciers allowing a significant increase in glacier flow. The Western Antarctic Ice Sheet is grounded below sea level and is therefore unstable. Papers published earlier this year indicated that this ice sheet was already in the early stages of disintegration. Note that it wasn't too long ago that Antarctica was thought to be stable to AGW impacts

 

Thanks. I was looking at the Reynolds SSTs down there and according to that site, I didn't notice a terrible + anomaly there outside the ice. Tough to find deeper underwater anomalies.

[StudentOfClimatology]

It is still too cold in Antarctica for ice sheet melting. My understanding is that warming ocean waters have weakened the floating ice shelves that are holding back key glaciers allowing a significant increase in glacier flow. The Western Antarctic Ice Sheet is grounded below sea level and is therefore unstable. Papers published earlier this year indicated that this ice sheet was already in the early stages of disintegration. Note that it wasn't too long ago that Antarctica was thought to be stable to AGW impacts

Problem with that theory is that a cooling has been observed in southern ocean SSTs as well. So it's not a viable suggestion. The only workable theory I know of is the SAM/PV/O^3/CFC forcing idea.

[The_Global_Warmer]

Thanks. I was looking at the Reynolds SSTs down there and according to that site, I didn't notice a terrible + anomaly there outside the ice. Tough to find deeper underwater anomalies.

 

The Southern Ocean has seen a huge flip and surge of heat being pushed down into the 0-1500M depths.

 

This is thru either 2011 or 2012.

 

The study this data came from wasn't about the Antarctic Sea Ice. But the data is legit. 

 

IMO considering the surface ssts as well as near surface OHC dropped for a while in the 2000s especially after the -PDO took hold indicates that a portion of the expanded ice area is from a wind circulation change that has caused collected heat to sink while promoting surface cooling.

 

Unlike the arctic basin the water around the sea ice is always very cold near almost all of it.  In that situation, small changes in wind, salinity, and upper ocean heat content can have large implications on how far the ice spreads.

 

 

 

 

[StudentOfClimatology]

Antarctica is losing land ice mass.

If true, it probably has more to do with ice sheet dynamics, though some studies point to the WAIS as a source region. Still difficult to find enough warming (if any) down there to induce a response like that.

[ORH_wxman]

Subsurface warming cannot be a real source for the glacier discharge unless it is shown that it Is barely below the surface. 0-1500m is useless for that. Given the obvious surface cooling of the ocean, my guess is 0-100m ohc has not seen any increase but I haven't seen data posted for that

[chubbs]

Melting of the underside of floating ice shelves by warmer sea water is the primary mechanism for unlocking susceptible glaciers.

 

http://climate.nasa.gov/news/937/

 

edit: added a graphic - Pine Island and Thwaites are the most susceptible glaciers.

 

[bluewave]

Geothermal heating plays a role also.

 

 

http://www.utexas.edu/news/2014/06/10/antarctic-glacier-melting/

 

Researchers Find Major West Antarctic Glacier Melting from Geothermal Sources

 

June 10, 2014

AUSTIN, Texas — Thwaites Glacier, the large, rapidly changing outlet of the West Antarctic Ice Sheet, is not only being eroded by the ocean, it’s being melted from below by geothermal heat, researchers at the Institute for Geophysics at The University of Texas at Austin (UTIG) report in the current edition of the Proceedings of the National Academy of Sciences.

The findings significantly change the understanding of conditions beneath the West Antarctic Ice Sheet where accurate information has previously been unobtainable.

The Thwaites Glacier has been the focus of considerable attention in recent weeks as other groups of researchers found the glacier is on the way to collapse, but more data and computer modeling are needed to determine when the collapse will begin in earnest and at what rate the sea level will increase as it proceeds. The new observations by UTIG will greatly inform these ice sheet modeling efforts.

 

Using radar techniques to map how water flows under ice sheets, UTIG researchers were able to estimate ice melting rates and thus identify significant sources of geothermal heat under Thwaites Glacier. They found these sources are distributed over a wider area and are much hotter than previously assumed.

The geothermal heat contributed significantly to melting of the underside of the glacier, and it might be a key factor in allowing the ice sheet to slide, affecting the ice sheet’s stability and its contribution to future sea level rise.

The cause of the variable distribution of heat beneath the glacier is thought to be the movement of magma and associated volcanic activity arising from the rifting of the Earth’s crust beneath the West Antarctic Ice Sheet.

Knowledge of the heat distribution beneath Thwaites Glacier is crucial information that enables ice sheet modelers to more accurately predict the response of the glacier to the presence of a warming ocean.

Until now, scientists had been unable to measure the strength or location of heat flow under the glacier. Current ice sheet models have assumed that heat flow under the glacier is uniform like a pancake griddle with even heat distribution across the bottom of the ice.

The findings of lead author Dusty Schroeder and his colleagues show that the glacier sits on something more like a multi-burner stovetop with burners putting out heat at different levels at different locations.

“It’s the most complex thermal environment you might imagine,” said co-author Don Blankenship, a senior research scientist at UTIG and Schroeder’s Ph.D. adviser. “And then you plop the most critical dynamically unstable ice sheet on planet Earth in the middle of this thing, and then you try to model it. It’s virtually impossible.”

That’s why, he said, getting a handle on the distribution of geothermal heat flow under the ice sheet has been considered essential for understanding it.

Gathering knowledge about Thwaites Glacier is crucial to understanding what might happen to the West Antarctic Ice Sheet. An outlet glacier the size of Florida in the Amundsen Sea Embayment, it is up to 4,000 meters thick and is considered a key question mark in making projections of global sea level rise.

The glacier is retreating in the face of the warming ocean and is thought to be unstable because its interior lies more than two kilometers below sea level while, at the coast, the bottom of the glacier is quite shallow.

Because its interior connects to the vast portion of the West Antarctic Ice Sheet that lies deeply below sea level, the glacier is considered a gateway to the majority of West Antarctica’s potential sea level contribution.

The collapse of the Thwaites Glacier would cause an increase of global sea level of between 1 and 2 meters, with the potential for more than twice that from the entire West Antarctic Ice Sheet.

The UTIG researchers had previously used ice-penetrating airborne radar sounding data to image two vast interacting subglacial water systems under Thwaites Glacier. The results from this earlier work on water systems (also published in the Proceedings of the National Academy of Sciences) formed the foundation for the new work, which used the distribution of water beneath the glacier to determine the levels and locations of heat flow.

In each case, Schroeder, who received his Ph.D. in May, used techniques he had developed to pull information out of data collected by the radar developed at UTIG.

According to his findings, the minimum average geothermal heat flow beneath Thwaites Glacier is about 100 milliwatts per square meter, with hotspots over 200 milliwatts per square meter. For comparison, the average heat flow of the Earth’s continents is less than 65 milliwatts per square meter.

The presence of water and heat present researchers with significant challenges.

“The combination of variable subglacial geothermal heat flow and the interacting subglacial water system could threaten the stability of Thwaites Glacier in ways that we never before imagined,” Schroeder said.

For more information, contact: University Communications, Office of the President, 512 471 3151;  Anton Caputo, Geology Foundation, Jackson School of Geosciences, 512-232-962

 

[The_Global_Warmer]

Subsurface warming cannot be a real source for the glacier discharge unless it is shown that it Is barely below the surface. 0-1500m is useless for that. Given the obvious surface cooling of the ocean, my guess is 0-100m ohc has not seen any increase but I haven't seen data posted for that

 

No one said anything of the sort.

[CAD_Wedge_NC]

Problem with that theory is that a cooling has been observed in southern ocean SSTs as well. So it's not a viable suggestion. The only workable theory I know of is the SAM/PV/O^3/CFC forcing idea.

 

   As much as Chubbs would like for you to believe that fresh water is responsible for this dramatic increase, it is not a viable solution, due to the decreasing temperature trends in the waters surrounding the ice sheet. What makes better sense is the +AAO, the ozone depletion factor, and the bipolar seesaw.

   While CFC's are on the decline, there could very well be a lagged response. However, we have to wonder, why isn't the NH responding in a similar fashion? Answer: The atmospheric circulation in the southern hemisphere is vastly different since the 1990's and warm water transport is not occurring at the same rate as it is in the North Atlantic. Bottom line here folks is that we still don't fully understand the reasoning behind this record uptick in sea ice, but to attempt to blame it on warm water and melting ice is foolish.

[Jonger]

Are you saying that glaciers are not melting in Antarctica?

They have probably been melting all along, that's why the negative anomalies continue the low hanging fruit melt.

[LithiaWx]

We have a new all-time record for ice extent in Antarctic in the satellite era.  That is something to write home about and is unprecedented in our times.  Very epic stuff happening down there.

[chubbs]

   As much as Chubbs would like for you to believe that fresh water is responsible for this dramatic increase, it is not a viable solution, due to the decreasing temperature trends in the waters surrounding the ice sheet. What makes better sense is the +AAO, the ozone depletion factor, and the bipolar seesaw.

   While CFC's are on the decline, there could very well be a lagged response. However, we have to wonder, why isn't the NH responding in a similar fashion? Answer: The atmospheric circulation in the southern hemisphere is vastly different since the 1990's and warm water transport is not occurring at the same rate as it is in the North Atlantic. Bottom line here folks is that we still don't fully understand the reasoning behind this record uptick in sea ice, but to attempt to blame it on warm water and melting ice is foolish.

 

No need to get in a tizzy. I just posted the article without making any attempt to compare it to other factors impacting Antarctic sea ice extent. If we don't understand the reasoning how can you discount a potentially important factor. 

[AvantHiatus]

Antarctica is losing land ice mass. 

 

Exactly, the rate of dumping is immense and causing abrupt behavior in SIE trends. The relationship is extremely inverse and opposite of what you would expect. AGW is designed to kill us in a slow methodical manner as to avoid urgency, relative to the human lifespan.

 

It appears to be a culmination of O3 depletion, CFCs, AAO cycles, and diminished Salinity/Increased meltwater. The glacier calving thing is 100% ocean dynamics. It does not make sense because it is nothing like the Arctic.

[chrisf97212]

Second, there has been no warming observed over the Antarctic region since the start of the satellite era:

The real reason behind the cooling Antarctic is related to the +SAM tendency as a result of O^3 depletion via both anthropogenic CFCs and a weakening magnetic field.

See the trend in the AAO:

 

 

As far as ozone, you didn't mention the sun's role.  More ultra violet irradiance means more ozone and more stratospheric heating.

[StudentOfClimatology]

As far as ozone, you didn't mention the sun's role. More ultra violet irradiance means more ozone and more stratospheric heating.

I think it works the other way around, actually. Increased solar activity accelerates O^3 photodissociation, mostly as a consequence of the solar wind. The solar wind eats up O^3 at a faster rate relative to production.

[chrisf97212]

I think it works the other way around, actually. Increased solar activity accelerates O^3 photodissociation, mostly as a consequence of the solar wind. The solar wind eats up O^3 at a faster rate relative to production.

Oops, thanks for the clarification.

[stadiumwave]

I'd like to compliment everyone for some great posts.  Very informative!!

[tacoman25]

   As much as Chubbs would like for you to believe that fresh water is responsible for this dramatic increase, it is not a viable solution, due to the decreasing temperature trends in the waters surrounding the ice sheet. What makes better sense is the +AAO, the ozone depletion factor, and the bipolar seesaw.

   While CFC's are on the decline, there could very well be a lagged response. However, we have to wonder, why isn't the NH responding in a similar fashion? Answer: The atmospheric circulation in the southern hemisphere is vastly different since the 1990's and warm water transport is not occurring at the same rate as it is in the North Atlantic. Bottom line here folks is that we still don't fully understand the reasoning behind this record uptick in sea ice, but to attempt to blame it on warm water and melting ice is foolish.

 

I agree that as we so often see, there are theories being presented as fact.

[tacoman25]

Exactly, the rate of dumping is immense and causing abrupt behavior in SIE trends. The relationship is extremely inverse and opposite of what you would expect. AGW is designed to kill us in a slow methodical manner as to avoid urgency, relative to the human lifespan.

 

Designed? By who? You make it sound like something brewed in a lab by an evil genius.

[Isotherm]

Designed? By who? You make it sound like something brewed in a lab by an evil genius.

 

 

AGW was personified in that statement as if it was Mike Myers from Halloween. Slow and methodical, AGW will tear us apart, piece by piece.

 

Wondering when the first horror movie will be made on this (entitled, "Death by AGW").

[AvantHiatus]

Designed? By who? You make it sound like something brewed in a lab by an evil genius.

Designed by fate, retribution for humanity's enslavement of the Earth.

 

Thom Hartmann

 

"Tipping points could be years, decades, or centuries down the road. The big danger is that you can only recognize them when it is too late to do anything about it"

[tacoman25]

Designed by fate, retribution for humanity's enslavement of the Earth.

 

Thom Hartmann

 

"Tipping points could be years, decades, or centuries down the road. The big danger is that you can only recognize them when it is too late to do anything about it"

 

Aaaannnnd....this illustrates how climate change is not just about science for many people.

 

There is a very real part of global warming activism rooted in a desire to see humans punished for their evil ways, or at least repent and change before it's too late. Not so different from many religious beliefs.

[chrisf97212]

Designed by fate, retribution for humanity's enslavement of the Earth.

 

Thom Hartmann

 

"Tipping points could be years, decades, or centuries down the road. The big danger is that you can only recognize them when it is too late to do anything about it"

I can't tell if you're trying to be funny or are serious.

[AvantHiatus]

I can't tell if you're trying to be funny or are serious.

There is truth to it, do your research on paleoclimate and lol @ comparing religion with AGW activism. It has way more integrity than a man in the clouds.

[The_Global_Warmer]

 

We have a new all-time record for ice extent in Antarctic in the satellite era.  That is something to write home about and is unprecedented in our times.  Very epic stuff happening down there.

 

 

 

If Antarctica gaining 5% extra ice volume is unprecedented.

What do you call the Arctic losing 70-80% of it's ice volume?