Blog author: jballor
by on Friday, August 12, 2005

Roy Spencer at Tech Central Station examines some of the latest climatology research published in the journal Science.

One essential point of the new findings is that the temperature readings based on satellite information may not be as reliable as previously thought. The satellite readings of the atmosphere had been at significant variance from surface temperature readings. As Spencer states of the article by Mears & Wentz, “Their final estimate of the global lower tropospheric trend through 2004 is +0.19 deg. C/decade, very close to the surface thermometer estimate, and this constitutes the primary news value of their report.”

You’re sure to hear about this trio of articles in the media, and Spencer asks, “What will all of this mean for the global warming debate? Probably less than the media spin will make of it.” Here’s a prime example of that prediction from LiveScience. In an article titled, “Key Argument for Global Warming Critics Evaporates,” Ker Than cites Roy Spencer as the head of “the only group to previously analyze satellite data on the troposphere” before the recently published reports.

In part due to the disagreement between the atmospheric and surface readings, Steven Sherwood, a geologists at Yale University and lead author of one of the studies admits that “most people had to conclude, based on the fact that there were both satellite and balloon observations, that it [the Earth] really wasn’t warming up.”

Than writes of the study that corrected an error in Spencer’s calculations: “After correcting for the mistake, the researchers obtained fundamentally different results: whereas Spencer’s analysis showed a cooling of the Earth’s troposphere, the new analysis revealed a warming.”

“When people come up with extraordinary claims — like the troposphere is cooling — then you demand extraordinary proof,” said Ben Santer, an atmospheric scientist and a lead author of another of the studies. “What’s happening now is that people around the world are subjecting these data sets to the scrutiny they need.”

Spencer himself is a bit more cautious about what the new research means. He concludes,

At a minimum, the new reports show that it is indeed possible to analyze different temperature datasets in such a way that they agree with current global warming theory. Nevertheless, all measurements systems have errors (especially for climate trends), and researchers differ in their views of what kinds of errors exist, and how they should be corrected. As pointed out by Santer et al., it is with great difficulty that our present weather measurement systems (thermometers, weather balloons, and satellites) are forced to measure miniscule climate trends. What isn’t generally recognized is that the satellite-thermometer difference that has sparked debate in recent years has largely originated over the tropical oceans — the trends over northern hemispheric land areas, where most people live, have been almost identical.

On the positive side, at least some portion of the disagreement between satellite and thermometer estimates of global temperature trends has now been removed. This helps to further shift the global warming debate out of the realm of “is warming happening?” to “how much has it warmed, and how much will it warm in the future?”. (Equally valid questions to debate are “how much of the warmth is man-made?”, “is warming necessarily a bad thing?”, and “what can we do about it anyway?”). And this is where the debate should be.