But in an AP news story, two of its authors (one is ‘hockey-stick’ inventor Michael Mann from the Real Climate blog) argue that this refutes the skeptics and is “consistent with” greenhouse warming. Of course, as Roger Pielke, Jr, points out, not long ago we learned from Real Climate that a cooling Antarctica was ‘consistent with’ greenhouse warming and thus the skeptics were wrong: “So a warming Antarctica and a cooling Antarctica are both ‘consistent with’ model projections of global warming. Our foray into the tortured logic of ‘consistent with’ in climate science raises the perennial question, what observations of the climate system would be inconsistent with the model predictions?”
The results are based on very few isolated data from weather stations, plus data from research satellites. And here is the rub: these are not data from microwave sounding units (MSU), such as are regularly published by Christy and Spencer, but data from infrared sensors that are supposed to measure the temperature of the surface (rather than of the overlaying atmosphere, as weather stations do).
But the IR emission depends not only on temperature of the surface, but also on surface emissivity — and is further modified by absorption of clouds and haze.
These are all difficult points. Emissivity of snow depends on its porosity and size of snow crystals. Blowing snow likely has a different emissivity than snow that has been tamped down; so surface winds could have a strong influence. The emissivity of ice is again different and will depend on whether there is a thin melt layer of water on top of the ice, temporarily produced by solar radiation. Finally, we have temperature inversions that can trap haze which is essentially undetectable by optical methods from satellites.
The proof of the pudding, of course, is the MSU data, which show a continuous cooling trend, are little affected by surface conditions and are unaffected by haze and clouds. They are therefore more reliable.
Bottom line: As it looks to me right now, the Antarctic Continent is cooling not warming.
1. Eric J. Steig, David P. Schneider, Scott D. Rutherford, Michael E. Mann, Josefino C. Comiso & Drew T. Shindell. Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year. Nature 457:459-463, 22 Jan. 2009; doi:10.1038/nature07669
Picture of Dr Singer taken in New York 2008 by Jennifer Marohasy.
This article is from SEPP Science Editorial #4-09 (1/24/09) republished here with permission.