"By Ronald Bailey

"Experimental models incorporating both anthropogenic and natural factors are consistent with the new analysis showing tropospheric warming," claims the press release heralding a new paper being published today in Science. This paper is supposed to be a knockout blow against the satellite dataset that has consistently and annoyingly (for the global warming alarmists) shown that the earth's atmosphere is NOT warming nearly as much as the computer climate models predict. The new analysis, meant to prove finally that dangerous man-made global warming is real, was done by a team led by long-time global warming proponent Benjamin Santer from the Lawrence Livermore National Laboratory.

So is it true? Have the satellites been wrong about global temperature trends? The paper it turns out is mostly hot air, adding nothing new to the climate change debate. Evidently, the strategy being used by Santer et al. is that if their models don't agree with the data, then change the data.

Since 1979, climatologists John Christy and Roy Spencer at the University of Alabama in Huntsville (UAH) have been using instruments aboard a variety of weather satellites to take the temperature of the earth's atmosphere daily. What they find is that the atmosphere is warming up at a rate of only about 0.05 degrees centigrade (+/- 0.05 C) per decade. This is considerably lower than the rate of warming predicted by the climate computer models. Now it is not unreasonable to think that perhaps the data contain some unaccounted for uncertainties - this is science after all, and you're only as good as your data.

Puzzled by the discrepancy between the satellite data and the models, Frank Wentz, a physicist working at Remote Sensing Systems (RSS) in Santa Rosa California, decided to check into the matter. Since 1979 whenever a new weather satellite was launched to replace old ones, scientists had to cross calibrate instruments taking into account things like orbital differences and slight variations in the instruments. Wentz looked at how the UAH team cross-calibrated the data from each of satellites and found that they had not taken into account variations between satellites due to their orbital decay.

Wentz published a 1998 bombshell paper in Nature claiming to show that once the satellite data were corrected that cooling trend identified by Christy and Spencer would in fact become a warming trend of 0.07 degrees centigrade instead of the 0.05 degree rate of cooling that the UAH team had found between the years 1979 and 1997. This was still considerably below the trend found in most models but it was positive. It is no surprise that global warming proponents hailed the RSS dataset as evidence that they are right.

As conscientious scientists, Christy and Spencer admitted that they had failed to take all of the orbital decay effect into account. They then painstakingly readjusted their data and found that the atmosphere was cooling at a 0.01 degree centigrade per decade rate. It seems that the RSS team had used data that had already been corrected for some of the effects and therefore over-corrected it to create a spurious warming trend.
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http://abob.libs.uga.edu/bobk/ccc/cc050703.html