Antarctic melting

If relatively warm ocean water can get under grounded ice, that ice may melt. See for example:

J. S. Greenbaum, D. D. Blankenship, D. A. Young, T. G. Richter, J. L. Roberts, A. R. A. Aitken, B. Legresy, D. M. Schroeder, R. C. Warner, T. D. van Ommen & M. J. Siegert (2015). Ocean access to a cavity beneath Totten Glacier in East Antarctica. Nature Geoscience 8, 294–298 doi:10.1038/ngeo2388

As at the other pole, mojo assumes that such water being warm has nothing to do with CO2. I find no reason to make that assumption.

Antarctic ice can also melt from geothermal heat below, if there is enough of it. Geothermal is certainly unrelated to atmospheric CO2. We have this:

Dustin M. Schroeder, Donald D. Blankenship, Duncan A. Young, and Enrica Quartini. (2014). Evidence for elevated and spatially variable geothermal flux beneath the West Antarctic Ice Sheet. PNAS 111 925), 9070–9072, doi: 10.1073/pnas.1405184111

Andrew T. Fisher, Kenneth D. Mankoff, Slawek M. Tulaczyk, Scott W. Tyler, Neil Foley, and the WISSARD Science Team, (2015). High geothermal heat flux measured below the West Antarctic Ice Sheet. Science Advances 1(6), e1500093 DOI: 10.1126/sciadv.1500093

The maximum heat flux they measured was 285 milliwatts per square meter. Global continental average is 65 milliwatts per square meter. So there is geothermal heating, but it is not (yet) known to be amazing. Elevated values are found in some places of ice loss but not in others. Unless it changed recently, it was present during ice formation as well. I find no reason to assume geothermal is the only cause.

Warm-water intrusion and geothermal patterns add to the complexity of understanding Antarctic ice dynamics. I see no simple resolution of this at local, regional or continental scales. The ice folks simply have to keep doing what they do. It dishonors their hard work for us to grasp at simplistic answers.

 

To make sense of geothermal heat flux we can consider more familiar examples. The entire Yellowstone region (where snow does accumulate in winter) averages 2 watts per square meter, and 20 watts at geothermal features (where snow does not accumulate).

Burying electrical heating cables to promptly melt all snow and ice; from an installation guide I calculate heating is 200 watts per square meter. That is an 'overkill level' where power is not continuously applied.

We can compare these to the max (so far) reported Antarctic level of 0.285 watts per square meter.

As always I think it rewarding (and not very difficult) to put things like this in perspective. But there are too many 'things' in this wide world. I often rely on PriusChat muses to select more interesting ones.

 

Another new study a part of Antarctica in negative ice balance:

Uneven onset and pace of ice-dynamical imbalance in the Amundsen Sea Embayment, West Antarctica - Konrad - 2016 - Geophysical Research Letters - Wiley Online Library

 

My post from that other thread in response to @5 being repeated here:

H. Jay ZWALLY, Jun LI, John W. ROBBINS, Jack L. SABA, Donghui YI, Anita C. BRENNER. (2015). Mass gains of the Antarctic ice sheet exceed losses. Journal of Glaciology, 61(230), 101-1036. doi: 10.3189/2015JoG15J071

Which is free to download. I would appreciate it as always if others would look at this and compare to other conclusions that appear to disagree. Or, if someone can find indications of discussions between Zwally and Velicogna? Those are the folks who know. There should be no need to rely on affinity websites here.

+++
As I also said over there Zwally et al. did something novel with ice cores in their analysis. Not something I can explain, but it seems to have contributed to their finding positive mass balance.

Other continent wide studies found negative ice balance, with wide variability. There may be 10 or 20 of those, many cited by this Zwally. Their group seems to be alone in finding positive, and that's OK. The ice folks simply need to get together and convince each other of the particular value of their own methods.

In the meantime we can content ourselves with another recent study:

Paolo, FS, Fricker, HA, Padman, L. (2015). Volume loss from Antarctic ice shelves is accelerating. Science 348(6232), 327-331.

Or with Zwally, as each sees fit. Paolo provide a nice graphic which Zwally group might offer to revise on a regional basis.


My post from that other thread in response to @5 being repeated here:

H. Jay ZWALLY, Jun LI, John W. ROBBINS, Jack L. SABA, Donghui YI, Anita C. BRENNER. (2015). Mass gains of the Antarctic ice sheet exceed losses. Journal of Glaciology, 61(230), 101-1036. doi: 10.3189/2015JoG15J071

Which is free to download. I would appreciate it as always if others would look at this and compare to other conclusions that appear to disagree. Or, if someone can find indications of discussions between Zwally and Velicogna? Those are the folks who know. There should be no need to rely on affinity websites here.

+++
As I also said over there Zwally et al. did something novel with ice cores in their analysis. Not something I can explain, but it seems to have contributed to their finding positive mass balance.

Other continent wide studies found negative ice balance, with wide variability. There may be 10 or 20 of those, many cited by this Zwally. Their group seems to be alone in finding positive, and that's OK. The ice folks simply need to get together and convince each other of the particular value of their own methods.

In the meantime we can content ourselves with another recent study:

Paolo, FS, Fricker, HA, Padman, L. (2015). Volume loss from Antarctic ice shelves is accelerating. Science 348(6232), 327-331.

Or with Zwally, as each sees fit. Paolo provide a nice graphic which Zwally group might offer to revise on a regional basis. Which I cannot upload today. But soon I hope

 

Paolo figure post later. Or you might be curious enough to get it yourselves.

Meanwhile, more research down there:

Antarctic 'pole of ignorance' finally addressed - BBC News

 

Paolo et al 2015 figure

 

Beyond the current situation, we have:


M. Frezzotti, C. Scarchilli, S. Becagli, M. Proposito, and S. Urbini (2013). A synthesis of the Antarctic surface mass balance during the last 800 yr. The Cryosphere, 7, 303–319, doi:10.5194/tc-7-303-2013


Using ice cores as paleo proxies they examine mass balance another way. Even though cores are not ‘coastal’, they reveal a dynamic place. TSI here means Total Solar Irradiance, and there is some indication of relationships between solar and Antarctic ice dynamics. Mojo will enjoy that, until realizing that the purported cold times often correspond to less ice. Anyway, that ice has had its ups and downs, found here to be increasing since 1850. During which times global surface air temperatures have also increased.





One wonders if these anomalies can be matched up with current dynamics. Which again, may be up to 300 gigatons per year negative (Paolo and most other studies), or 80 gigatons per year positive (Zwally). Paolo et al. 2015 does address Zwally’s claims; another reason to read it.

 

Maybe some would collect this very large file:

A.J. Simmons, P. Berrisford, D. P. Dee, H. Hersbach, S. Hirahara and J.-N. Thépaut (2016). A reassessment of temperature variations and trends from global reanalyses and monthly surface climatological datasets. Quarterly Journal of the Royal Meteorological Society DOI: 10.1002/qj.2949

I mention it here for one sentence from Abstract:

“None of the datasets exhibit net warming over the Antarctic since 1979.”

To what extent Antarctic ice is melting, it thus seems not because of warmer air overhead. As forcing factors we have warmer water lapping on margins, (sometimes like now) less marginal sea ice as ‘dams’ against unloading, and geothermal heat flux. The latter of course to have dynamic effect would need to be changing, but no one has suggested so.

We have current local observations that parts of WAIS now show surface fissures, which may portend ‘big enough to talk about’ future ice dumps. If not, business as usual. If so, real, serious ‘climate/fossil-C/energy/human enterprise’ discussion might commence.