For years now global warming skeptics have been using satellite measurements to argue that global warming isn’t happening, For example (from 1998):
Surface-based temperature records are too few in number and too unevenly spaced to generate accurate global temperature maps. Only 30 percent of the world’s surface is land, so land-based temperature stations measure less than one-third of the Earth’s climate. Urban stations, which are influenced by city heat anomalies, are over-represented; deserts, mountains, and forests are under-represented.
The global temperature record produced from satellite data has none of the problems faced by surface-based thermometers. Orbiting satellites cover 99 percent of the Earth’s surface, not less than a third, and measure a layer of the troposphere that is above the effects of urban heat islands.
Satellite measurements are accurate to within 0.001 C. Because new satellites are launched into orbit by the National Aeronautics and Space Administration (NASA) before old ones are retired, overlapping data sets are created, ensuring that the new satellites are calibrated correctly. …
According to Dr. Roy Spencer, meteorologist and team leader of the NASA/Marshall Space Flight Center, “The temperatures we measure from space are actually on a very slight downward trend since 1979 … the trend is about 0.05 C per decade cooling.”
Then other scientists analysed the satellite data and found that it showed warming similar to the surface record. Global warming skeptics didn’t miss a beat — obviously the scientists who got results the skeptics didn’t like were guilty of fraud:
atmospheric data from both satellites and weather balloons show only a trifling rise in temperature over the past couple of decades, while the surface temperature has been rising steadily. In 2000, a National Research Council study confirmed the data’s discrepancy with the model.
The proper scientific response would be to reexamine the models and adjust them to fit reality. But that hasn’t happened in climatology. Instead, there have been repeated attempts to manipulate the satellite data fit the models. Recently, a study published in the journal Nature tries to hammer the square peg of the satellite data into the round hole of the theory, using a method that satellite temperature experts John Christy and Roy Spencer of the University of Alabama at Huntsville had considered and rejected as incorrect in 1991.
So I’m wondering how the skeptics will spin the latest development. Spencer and Christy have revised their numbers and now they seem to agree with the surface record. William Connolley
has a nice plot of the new numbers.
Update: Connolley has posted some more graphs and links.