Here's the original article which set off the exchange:

Lawrence Solomon: Climate change’s Antarctic ruffle
Posted: January 31, 2009, 2:22 AM by NP Editor
How does a new Nature study conclude that Antarctica is warming when actual temperature readings show it is not?
By Lawrence Solomon

For two decades now, those predicting climate-change catastrophe have been frustrated by skeptics who ask, “If carbon dioxide is warming the planet, why does the data show Antarctica to be cooling?” Until last week, the doomsayers had all manner of complicated explanations but no slam dunk answer. Now, thanks to a new study published last week in Nature magazine, the doomsayers obtained the answer they sought — proof that any fool can understand. The bottom line: Antarctica is in fact warming, just like the rest of the planet. “Contrarians have sometime grabbed on to this idea that the entire continent of Antarctica is cooling, so how could we be talking about global warming,” elaborated Michael Mann, director of the Earth System Science Center at Penn State University and a co-author of the Nature study. “Now we can say: No, it’s not true ... It is not bucking the trend.”

The press seized on the findings. “Antarctica is warming, not cooling: study,” announced a Reuters headline. “Global warming hits Antarctica,” stated CNN. “Antarctica joins rest of the globe in warming,” said the Associated Press. But this study in Nature leaves many unimpressed, including top scientists from the doomsayer camp. One week after the study’s release, it is clear this study does nothing to explain the enigma of a cooling Antarctica.

The Nature authors had a daunting challenge. For one thing, the U.S. government has maintained a scientific base at the South Pole since 1957 at which temperatures have been continuously measured. The temperature readings show a cooler climate over the past half century. For another, various weather stations in Antarctica record cooler temperatures. Moreover, satellite readings of temperatures above Antarctica show a cooling trend. Little wonder that the UN’s Intergovernmental Panel on Climate Change itself rejects the warming hypothesis. In its 2007 report, the IPCC accepts that Antarctica shows a “lack of warming reflected in atmospheric temperatures averaged across the region.” To reconcile Antarctica with the rest of the globe, global warming advocates have taken the simple, if unsatisfying, view that the lack of warming in Antarctica is consistent with the presence of warming everywhere else.

How do Mann and the other scientists involved in the Nature study now conclude that Antarctica is warming when actual temperature readings show it is not? Antarctica’s weather stations cover a small fraction of the continent. Where data doesn’t exist, Mann makes various assumptions, then deduces Antarctic temperatures over the last 50 years with the help of computer models. The official explanation: “The researchers devised a statistical technique that uses data from satellites and from Antarctic weather stations to make a new estimate of temperature trends.”

Are these statistical techniques reliable?

“I have to say I remain somewhat skeptical,” states Kevin Trenberth, a lead author for the IPCC and director of climate analysis at the National Center for Atmospheric Research. “It is hard to make data where none exist.”

Such results “have no real way to be validated,” states John Christy, an atmospheric scientist at the University of Alabama-Huntsville. “We will never know what the temperature was over the very large missing areas that this technique attempts to fill in.”

“How do the authors reconcile the conclusions in their paper with the cooler than average long-term sea-surface temperature anomalies off of the coast of Antarctica?” asked Roger Pielke, senior scientist at the University of Colorado in Boulder, in noting one of several failings in the study.

Michael Mann and Nature are not new to political controversy, or dubious science. The two collaborated before — in publishing what became known as the hockey-stick graph. This graph — which showed the 1990s to be the hottest decade of the hottest century of the last thousand years — became one of the most publicized facts of the year when it was published. Then the hockey stick became slapstick as it became an object of ridicule: Mann’s statistical techniques were shown to be entirely invalid and Mann was shown to have lacked the statistical knowledge demanded by the study. Mann and Nature refused to make public the data used to produce the graph, Nature refused to publish a response rebutting the hockey stick graph and Nature’s peer review process was shown to be a sham.

It took years, and a U.S. Congressional committee, to finally resolve the dispute, to Mann’s and Nature’s shame. Mercifully, the verdict over the latest offering from these two is seeing a speedier resolution.

Financial Post

Most of the Antarctic mass loss comes from Western Antarctica with a mass loss of 148 ± 21 km3/year. The mass loss from East Antarctica is 0 ± 56 km3/year. Because of its relatively large uncertainty, it's uncertain whether East Antarctica is in mass balance or not.

Why is Western Antarctica losing ice mass while East Antarctica is relatively steady. The hole in the ozone layer above the South Pole causes cooling in the stratosphere. This increases circular winds around the continent preventing warmer air from reaching east Antarctica and the Antarctic plateau. The flip side of this is the Antarctic Peninsula in Western Antarctica has "experienced some of the fastest warming on Earth, nearly 3°C over the last half-century".

http://www.skepticalscience.com/antarctica-gaining-ice.htm

See figure below: Monthly ice mass changes and their best-fitting linear trends for WAIS (red) and EAIS (green) for April 2002 to August 2005.

Also was this quote supposed to be a ringing endorsement Muso?

Based on the analyses presented in the original papers by Mann et al. and this newer supporting evidence, the committee finds it plausible that the Northern Hemisphere was warmer during the last few decades of the 20th century than during any comparable period over the preceding millennium. The substantial uncertainties currently present in the quantitative assessment of large-scale surface temperature changes prior to about A.D. 1600 lower our confidence in this conclusion compared to the high level of confidence we place in the Little Ice Age cooling and 20th century warming. Even less confidence can be placed in the original conclusions by Mann et al. (1999) that "the 1990s are likely the warmest decade, and 1998 the warmest year, in at least a millennium" because the uncertainties inherent in temperature reconstructions for individual years and decades are larger than those for longer time periods, and because not all of the available proxies record temperature information on such short timescales." 

pjb05 wrote on Jul 8^th, 2009 at 11:23am:



As I said, the original Mann report has been largely supported by subsequent independent studies.

As for the section in bold, I agree. If you read it carefully, it's talking about two very specific conclusions. Modern studies would not make such claims for individual years. Do you think you could explain the section that I highlighted to Grendel? It puts the previous section in context. Climate science has come a long way since Mann's report, although it's very useful from a historical perspective.

Now that we have more rigorous studies, it's time to archive the older studies as secondary data. If anyone continues to use datasets that are less representative in preference to more rigorous studies, you'd have to question their motivation.