Collapse Of Antarctic Ice Sheet Would Likely Put Washington, D.C. Largely Underwater

[arachadillo]

33. Comparative Polar Warming Trends

Last edited Wed May 2, 2012, 01:43 AM - Edit history (10)

"So that graph is primarily due to the ozone layer repairing itself?"

At first glance, the way I read the graph and the story about loss of ice shelves, my hypothesis is no, ice shelf loss is not a function (at least a statistically significant function) of changes in the size of the Antarctic ozone hole.

Discussions of changes in Antarctic ice normally divide into the three types of ice, sea ice, ice shelves, and ice sheets.

The ice shelves are the ice patches attached to the continent. At first glance, the NASA story on ice shelf loss correlates strongly with increased ocean temperatures around the continent.

The General Circulation Models (GCMs) currently used (and refined over the past three and one half decades) generally predict the "warming" associated with the concept "global warming" will be most significant in the polar regions, with the amount of warming (as measured in temperature days or something like that) diminishing as one moves to the equator.

Now, when one considers the topic as climate change, rather than global warming, it sounds reasonable to suggest that even absent the extreme temperature changes predicted for the polar regions, the climate variations attached to changing temperatures will either adversely or positively affect different areas of the globe.

As far as polar climate comparisons, the increased warming trends predicted by the GCMs appear to fit the Arctic and circumpolar north better than the fit the Antarctic and Southern Ocean areas.

Part of the reason for the less than perfect fit between the GCM predictions and the Antarctic, at least as I read the scientific literature, is that the ozone hole over Antarctica provides an endogenous environmental factors that acts as a stumbling block for increased warming and melting of the Antarctic ice sheets.

Nonetheless, again, as I read the scientific literature, Southern Ocean warming trends, also predicted by the GCMs, are being experienced, and do provide a reasonable explanation of the melting of the ice shelves.

Addendum: Thought it might be helpful to link to the British Antarctic Survey position Antarctica and Climate Change

"The majority of long-term measurements from Antarctic research stations show no significant warming or cooling trends, and temperatures over most of the continent have been relatively stable over the past few decades. The effects of the ozone hole have shielded much of the Antarctic continent from the impact of ‘global warming’."

I recognize the original post of this thread focused on the ice sheets, specifically the West Antarctic Ice Sheet. For one reason or another, the discussion drifted to the issue of ice shelves, and, at first glance, it looked to me as if the topics were conflated.

Addendum #2: Quite an interesting puzzle....
According to The University Corporation for Atmospheric Research UCAR the causal link for the ozone hole and the relatively stable continental temperatures over time, appears to be formally presented as
Antarctica ozone hole ---> changes in Southern Annular Mode (SAM) ---> current Antarctic (at least continental) weather patterns

OTOH,

Over at the Westher Channel they show nice graphs of the prevailing wind patterns over Antarctica, with the general flow pattern starting at the pole and moving outward, appearing to be formally presented as
Normal Antarctica wind patterns + warmer air along the western antarctic ----> current ice shelf loss.

Because the research in question does not indicate which wind causal pattern they use for their research, it could very well be the case that the first causal path,
Antarctica ozone hole ---> changes in Southern Annular Mode (SAM) ---> Southern Ocean currents ---> Antarctic (at least continental) weather patterns

Sometimes, the scientific research can be a bit difficult to read. The article, http://www.aos.princeton.edu/WWWPUBLIC/sara/statistics_course/papers/lovenduski_grl_05.pdfImpact of the Southern Annular Mode on Southern Ocean circulation
and biology]
again, at least at first glance, appears to be supporting this causal change, however it does not introduce the concept of the ozone hole as a primary factor driving variability in the SAM. It does, however, appear to be testing the hypothesis that
changes in Southern Annular Mode (SAM) ---> Southern Ocean currents ---> Antarctic (at least continental) weather patterns
figure 1 appears to show a strong correlation with SAM and winds, and ocean currents
there appears to be a less strong correlation with SAM, winds and sea surface temperatures (SST) , with the only increased temperature correlations found around the area in question, western Antarctica and the Antarctic peninsula.

from this reading, it remains possible that the ozone hole, does account for changing ice shelves (at least in a statistically significant way), thus falsifying (in the Popperian mode) my original hypothesis

researchers may adopt the second causal chain,
Normal Antarctica wind patterns + warmer air along the western antarctic ----> current ice shelf loss
as appears to be done by a researcher at Lamont-Doherty Earth Observatory
with a more sophisticated model
changing ocean currents (implicitly caused by a changing climate?) ---> warmer air along the western antarctic ----> current ice shelf loss
then my first statement,
"At first glance, the way I read the graph and the story about loss of ice shelves, my hypothesis is no, ice shelf loss is not a function (at least a statistically significant function) of changes in the size of the Antarctic ozone hole."
would be, in the Lakatos verification rather than falsification tradition, remain sound, because the global current conveyor belt serves as the impetus of change.

Not knowing how researchers hypothesize the relationship between changing wind patterns and ocean currents, naturally adds an element of uncertainty into any analysis. Either way, the researcher from Lamont-Doherty Earth Observatory explains how climatologists continue to work on both their modeling and data collection, just as they have done over the past forty years.
All things being equal, their partial explanations (or partial models) continue to remain robust in their ability to explain and describe the phenomena in questions, as well as provide above average predictive power.

It also sounds reasonable to assume that changing ocean temperatures around the continent are a function of both traditional Antarctica wind patterns and new Antarctica (and Southern Ocean) wind patterns introduced by the presence of the Antarctica ozone hole. The NASA researchers appear to be building this type of argument or theory in their Antarctic Sea Ice presentation.