There even remains -- in the United States, at least -- controversy over whether global temperatures are rising and, if so, how much.

A recent paper in the British journal Nature claims to have found a way out of at least one dilemma that has plagued climate research for years: the rise in temperatures in the lower atmosphere that is slower than the climate computer models have predicted, at least in relation to data on heating of the surface. This discrepancy has been the linchpin of the arguments by climate skeptics.

A University of of Washington team led by atmospheric researcher Qiang Fu re-analyzed the satellite data underlying the conclusion about the lower atmosphere. After applying some compensating factors, they now argue that temperature trends in the lower atmosphere are, in fact, consistent with the trends on the surface.

Microwave sounding units aboard polar-orbiting satellites run by the National Oceanic and Atmospheric Administration measure radiation emitted at different frequencies and provide temperature and other data for different layers of the atmosphere.

Channel two on those satellites measures tropospheric temperatures, the layer from the surface to about 7.5 miles up, while channel four measures temperatures in the stratosphere -- above 7.5 miles.

One well-known -- albeit counterintuitive -- greenhouse effect is the cooling of the stratosphere. Fu and his team found about one-fifth of the signal from the troposphere on channel two actually was coming from the stratospheric cooling. So they used statistical methods to subtract this phenomenon from the record and recalculated the warming rate of the troposphere.

The team concluded the troposphere was warming at the rate of about 0.2 degrees Celsius (nearly 0.4 degrees Fahrenheit) per decade, a result that fits almost perfectly with the predictions of the climate models.

"If the models agree with what has happened in the real world, that gives them more credence," said Kevin Trenberth, head of global climate analysis for the National Center for Atmospheric Research in Boulder. "The main cry of the skeptics is that the models don't agree with the tropospheric temperature change. What (the journal article) suggests is that the record agrees extremely well in the troposphere."

The finding seems to invalidate the data presented by researchers such as a group at the University of Alabama, Huntsville, one of the originators of the tropospheric anomaly.

"You'll hear an outcry from the skeptics," Trenberth told United Press International.

Indeed, John Christy, a member of the UAH team that compiled the tropospheric temperature record -- from the same satellite data that Fu and colleagues used -- said the University of Washington group subtracted out more cooling than exists and therefore their results are wrong.

Furthermore, Christy said, he and his colleagues previously had tried the method Fu used and found it did not work.

"In 1992 we published a means to eliminate the stratosphere," Christy told UPI. "We indicated in there that we had tried these multichannel methods, but that they were not suitable."

That is why, he said, his team used the single channel method.

"He can claim whatever he wants," Fu told UPI. "He never showed it in a paper. This method is very effective."

Christy responded that "there was no paper about it because, well, it didn't work. We went down a different road. It wasn't worth showing because it didn't work."

For the method used by Fu's team to be effective, Christy said, there has to be considerable overlap in the signals between satellite channels two and four.

"There is not enough overlap," he added. "There is not enough information in channel four to completely remove the stratospheric part of channel two."

In other words, there has to be enough cooling signal to subtract, and Fu and his colleagues subtracted more cooling than warranted by the data, Christy said.

"I think what bothers me at this point is the lack of attention given to all of the work we did in the early 1990s recognizing that methods such as Fu's were inappropriate," Christy continued. "Everyone knows there is stratospheric influence in channel two, but Fu makes it out as if he discovered this. Our method works, and has also been verified in a large number of published papers by investigators independent of ourselves."

Christy and his colleagues are not entirely entirely skeptical about warming. Their data do find a mean warming trend of 0.08 degrees C per decade. But the 0.2 degrees C per decade from Fu's team -- and from most climate models -- is about 1.5 times higher, which amounts to a considerable difference.

"This kind of mistake would not get published with adequate peer review of manuscripts submitted for publication," said Roy Spencer, principal research scientist at UAH on his climate change Web site. "But in recent years, a curious thing has happened. The popular science magazines, Science and Nature, have seemingly stopped sending John Christy and me papers whose conclusions differ from our satellite data analysis. This is in spite of the fact that we are (arguably) the most qualified people in the field to review them."

NCAR's Trenberth, one of the reviewers of the Fu paper, said, "I think the protests are silly ... I think this is the cleanest indication of what is actually happening in the troposphere from the standpoint of the satellite record."

So the argument continues.

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