12 March 2010

WUWT trumpets result supporting climate modelling

The recent article at WUWT
NSIDC Reports That Antarctica is Cooling and Sea Ice is Increasing trumpets the observation that Antarctic sea ice is increasing.  This is expected from climate modeling.  Nice to see someone else is picking up on this interesting confirmation of our scientific expectation.

The prediction is old.  In 1992 Manabe and coworkers, in running a changing CO2 experiment, noticed that the Antarctic sea ice cover increased with increasing CO2.  They traced this to increased fresh water on the Antarctic ocean, which derived from increased precipitation -- snow.  They also observed in their model that the Arctic ocean sea ice experienced a marked decline in thickness, and major loss of extent in the summer, but not so large a decrease in the winter.  At the time they wrote, it was still being debated whether there were trends in the Arctic or Antarctic sea ice covers.

The trend in Antarctic ice cover managed to be statistically significant by about 1997, as documented in

D. Cavalieri, P. Gloersen, C. L. Parkinson, J. C. Comiso, H. J. Zwally,
"Observed Hemispheric Asymmetry in Global Sea ice Changes", Science,
278, pp 1104-1106, 1997.  And it was indeed the expected (by Manabe and coworkers) increase.  As well as the expected decrease in the Arctic.

That left the question of the mechanism.  Did Manabe and coworkers identify the correct reason for the sea ice expansion?  Increased snowfall on Antarctic sea ice was documented in 2006 --

Markus, T., and Cavalieri, D. J., "Interannual and regional variability
of Southern Ocean snow on sea ice", Annals of Glaciology, 44, pp 53-57, 2006. (sorry, paywall here).

Since I'm a modeller, I focus on the modelling aspect.  Skeptical science (recently added to blogroll) has a different take about Antarctic sea ice, looking more at atmospheric and ocean temperatures
Watts Up With That's ignorance regarding Antarctic sea ice, with more to come.


Anonymous said...

Good reminder. I remember presentations by Claire Parkinson on this topic of Antarctic Sea Ice expansion a decade ago. The obvious control to sea ice beside temperature and the salinity of the surface layer, is the wind field. This has been examined by Turner et al. (2009) and is nicely reviewed by NASA who has long been reporting the lack of an Antarctic sea ice decline What's holding Antarctic sea ice back from melting

Horatio Algeranon said...

After Anthony Watts' recent false claim (debunked by Tamino (currently being written up for peer review) and others) that the station "dropouts" have introduced a warming trend in the surface temperature record AND particularly after his suggestion (based on the above claim) that the dropouts may actually have been part of a "deception" (Watts' own word*), he does not have much (if any) credibility left at this point.

...but he apparently still has a lot of fans.

What does that tell you?

*see "SURFACE TEMPERATURE RECORDS: POLICY DRIVEN DECEPTION?" SPPI, Jan 29, 2010 -- Anthony Watts and Joseph D’Aleo
(the title itself is quite telling)

Jes├║s R. said...

However, though to a lesser extent than in the Northern Hemisphere, the IPCC models also expected a decrease in the Southern Hemisphere sea ice:


Hank Roberts said...

Oy. Knappenberger.


Hank Roberts said...

"In 20th- and 21st-century simulations, antarctic sea ice cover is projected to decrease more slowly than in the Arctic (Figures 10.13c,d and 10.14), particularly in the vicinity of the Ross Sea where most models predict a local minimum in surface warming. This is commensurate with the region with the greatest reduction in ocean heat loss, which results from reduced vertical mixing in the ocean (Gregory, 2000). The ocean stores much of its increased heat below 1 km depth in the Southern Ocean."

That suggests a question; is there more vertical mixing and so more warm ocean water rising from below to nearer the surface than Gregory (2000) expected? Or something else?

Hank Roberts said...

ah, people have been writing about this:

Hank Roberts said...

Another prediction confirmed:

We report for the first time on the discovery of calcium carbonate crystals as ikaite (CaCO3*6H2O) in sea ice from the Arctic (Kongsfjorden, Svalbard). This finding demonstrates that the precipitation of calcium carbonate during the freezing of sea
ice is not restricted to the Antarctic, where it was observed for the first time in 2008. This finding is an important step in the quest to quantify its impact on the sea ice driven carbon cycle and should in the future enable improvement parametrization sea ice carbon models.
Precipitation of calcium carbonate, during the formation of sea ice is considered fundamental in catalyzing chemical processes such as the boundary layer ozone depletion events (ODEs) (Sander et al., 2006; Piot and von Glasow, 2008; Sander and Morin, 2009), as well as the formation and subsequent draw down of CO2 via brine drainage (Rysgaard, 2007, 2009). Furthermore, calcium carbonate found in firn off Talos Dome, Antarctica is thought to originate from sea ice and therefore could act as a proxy for sea ice cover (Sala et al., 2008). It has to be noted that until recently all these considerations were based on theoretical calculations and data from laboratory experiments. Obviously, due to the lack of direct confirmation of calcium carbonate precipitation in sea ice, estimates on its significance in the sea ice carbon cycle and consequently for polar or even global carbon budgets (Jones and Coote, 1981; Rysgaard et al., 2007, 2009) have been constrained. However, direct evidence of calcium carbonate precipitation based on field observations was obtained for the first time in 2008 (Dieck- mann et al., 2008), after decades of controversial discussion on its possible existance.....

Hank Roberts said...

hey, another prediction from the models. Does anyone have a collection point for these?

RS Lindzen - Bulletin of the American Meteorological Society, 1990: ... models (at least in the current literature) ... suggest that a warming of at least 0.5°C should already have occurred ..."

Ground warming patterns in the Northern Hemisphere during the last five centuries
Earth and Planetary Science Letters, 2004
"We observe warming of almost 1[degree]C for the last five centuries, half of this warming occurred during the last 50 years."

not a dothead said...

Linking manmade CO2 to increases in
antarctic sea ice is ludicrous.
Zero proof of that.

Robert Grumbine said...

It's easy to make an assertion on a blog. If you think Manabe is wrong, the thing to do is write your own paper for the scientific literature that shows how it is that he is wrong.

Neven said...

I have linked to this blog post in the latest Sea Ice Extent update on my Arctic Sea Ice blog.

I was wondering if there is an archive of some sorts where I can retrieve images of previous dates for this daily updated SST image?

Robert Grumbine said...

Hi Neven,

I'd recently started looking in at your place. I'll make mention in a more visible location.

For the SST analysis, there is no archive of the images (yet), but the data files are archived and you can use, for instance, GrADS to plot them as you would like. The data archive is at ftp://polar.ncep.noaa.gov/pub/history/sst/ophi
(ophi for the high resolution, omit that for the low (0.5 degree lat-long) resolution analysis).

Neven said...

Thanks, Robert, but that looks a bit too complicated, especially as I'm running low on time and mental capacities. If only for the fact that I'm working on a Windows machine, and I have no idea how to install GrADS in aCygwin environment. I'm a citizen scientist of the level of Anthony Watts.

So I'll just keep copying the daily images for another 1-2 weeks. I think my timing is still OK: If that ice in the Beaufort and East Siberian Seas finally starts melting for real an animation of the SST images should look interesting as well.

Hank Roberts said...

Oboy, what's missing here?


"Christine Dell'Amore
National Geographic News
Published August 16, 2010

Climate scientists have cracked the mystery of why Antarctic sea ice has managed to grow despite global warming .... Antarctic sea ice has mysteriously expanded, according to study leader Jiping Liu, a research scientist at Georgia Tech in Atlanta.

'We've seen this paradox, but we don't know why—here we gave an explanation,' Liu said...."

The word verification says:

Hank Roberts said...

Hang on, I found a better place to ask: http://www.collide-a-scape.com/2010/08/18/the-tribal-outcast/comment-page-3/#comment-15242

Hank Roberts said...

Dr. Curry is taking questions on the science at William's place:

Hank Roberts said...

"Our model results strongly suggest that processes not linked to stratospheric ozone depletion must be invoked to explain the observed increase in Antarctic sea ice extent."

Robert Grumbine said...

It's been interesting to watch how this has been playing out in the blogosphere. Given, for instance, mspelto's comment, I was surprised to see Judy's comment at stoat about how I had filled in missing pieces.

For those who haven't been following details on this, I'll encourage you to follow up the links from mspelto and hank regarding Antarctic sea ice. Comments by Lazar at stoat are perhaps especially illuminating as to whether I was doing anything original (the filling in blanks Judy mentioned) or just had a better memory of Manabe's work.

I'll also mention that Judy (Dr. Judith Curry) has now started blogging at http://judithcurry.com/ Her approach and starting points are different from mine. Up to you as to whether that's a good thing. But if you decide not, I'll encourage you also to not reach the conclusion lightly.

Hank Roberts said...

A postscript -- I mentioned/linked this thread over at RC to answer a new reader's question; Gavin followed up suggesting referencing
"CMIP3 Antarctic sea ice changes, but I don't have it at hand. This would be the appropriate source for any statements. - gavin]

Are those available?

Hank Roberts said...

and from a little amateur poking around:

Kirkman, Clark H., Cecilia M. Bitz, 2011: The Effect of the Sea Ice Freshwater Flux on Southern Ocean Temperatures in CCSM3: Deep-Ocean Warming and Delayed Surface Warming.

J. Climate, 24, 2224–2237.
doi: http://dx.doi.org/10.1175/2010JCLI3625.1
Volume 24, Issue 9 (May 2011)


Data request from modellers for Antarctic sea ice modelling http://www.
astr.ucl.ac.be/users/fmasson/ASPECT_request_modelers_v1.1.pdf (from 2010) (found via a footnote in this late 2011 meeting note) Observational needs for sea ice models Short note