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Global warming may not be the culprit after all when it comes to Artic changes

Climate data can be difficult to analyze. Take for instance global temperature changes. Whereas the Northern Hemisphere has been warming, the Southern half of the planet is cooling. While Antarctic Ice is at near-record levels, the Northern Pole is warming at an unprecedented pace-- much faster than global warming models predict.

A new study published in the journal Nature identified a possible cause for this discrepancy. It identifies a natural, cyclical flow of atmospheric energy around the Arctic Circle. A team of researchers, led by Rune Graversen of Stockholm University, conclude this energy flow may be responsible for the majority of recent Arctic warming.

The study specifically rules out global warming or albedo changes from snow and ice loss as the cause, due to the "vertical structure" of the warming ... the observed warming has been much too weak near the ground, and too high in the stratosphere and upper troposphere.

This study follows hot on the heels of research by NASA, which identified "unusual winds" for rapid Arctic ice retreat. The wind patterns, set up by atmospheric conditions from the Arctic Oscillation, began rapidly pushing ice into the Transpolar Drift Stream, a current which quickly sped the ice into warmer waters.

A second NASA team, using data from the the GRACE (Gravity Recovery and Climate Experiment) satellite, recently concluded that changes in the Arctic Oscillation were "mostly decadal in nature", rather than driven by global warming.



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RE: Wrong again Masher
By Rovemelt on 1/5/2008 12:54:41 PM , Rating: 0
Masher, that publication you're referencing is over 10 years old.

This recent publication (2007) shows the antarctic shrinking:

http://www.sciencemag.org/cgi/content/abstract/315...

Here is the abstract with some interesting points highlighted:

quote:
Recent Sea-Level Contributions of the Antarctic and Greenland Ice Sheets
Andrew Shepherd1 and Duncan Wingham
Science 16 March 2007:
Vol. 315. no. 5818, pp. 1529 - 1532

After a century of polar exploration, the past decade of satellite measurements
has painted an altogether new picture of how Earth's ice sheets are changing. As global temperatures have risen, so have rates of snowfall, ice melting, and glacier flow. Although the balance between these opposing processes has varied considerably on a regional scale, data show that Antarctica and Greenland are each losing mass overall. Our best estimate of their combined imbalance is about 125 gigatons per year of ice, enough to raise sea level by 0.35 millimeters per year. This is only a modest contribution to the present rate of sea-level rise of 3.0 millimeters per year. However, much of the loss from Antarctica and Greenland is the result of the flow of ice to the ocean from ice streams and glaciers, which has accelerated over the past decade. In both continents, there are suspected triggers for the accelerated ice discharge—surface and ocean warming, respectively—and, over the course of the 21st century, these processes could rapidly counteract the snowfall gains predicted
by present coupled climate models.


Sorry, but there just isn't enough data to suggest that the southern hemisphere is cooling. What may appear to be conflicting data may not be...basically it looks as if mass is shifting around the antarctic, but antarctic temperatures seem to be on a slow gradual increase, albeit with the regional variations you point out.

Greenland too, as measured by both satellite radar interferometry and time-variable gravity measurements seems to be slowly shrinking:

http://www.sciencemag.org/cgi/content/abstract/112...


RE: Wrong again Masher
By masher2 (blog) on 1/5/2008 1:06:30 PM , Rating: 3
> "Masher, that publication you're referencing is over 10 years old."

Eh? It was published July 2006. Also the UAH NOAA data (as well as the cryosphere data posted by AW) is current as of 2007. The *oldest* study I cited was published in 2002, and it examined the cooling trend in Antarctica from 1986-2000.

Furthermore, the study you cite refers to mass balance only, and isn't even a study of Antarctic (much less SH) temperatures at all. As you yourself have pointed out many times, there isn't a direct relationship between the two. Cooling temperatures can (and often do) imply less snowfall.

Sea ice, however, is directly coupled to temperature. And sea ice is unequivocally increasing.


RE: Wrong again Masher
By Rovemelt on 1/5/2008 1:27:16 PM , Rating: 3
You're right, I misread it as 1996...it says 2006.


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