Climate Change Sceptics Using Bad Data

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Climate Change Sceptics Using Bad Data

Written by SerenaStargazer

Saturday, 20 August 2005

Three independent studies have shown that sceptics who claim that the Earth is not getting warmer have been using faulty data to prove their viewpoint. The temperature of the lower troposphere, the lowest part of the Earth’s atmosphere, has been an important issue in discussions on climate change. If the Earth’s surface is warming, then the lower troposphere should be warming as well. However, in 1992, John Christy of the University of Alabama in Huntsville analysed satellite measurements and determined that, over the decades, the lower troposphere has cooled relative to the Earth’s surface over the tropics. While those arguing that the Earth was not warming took this as a sign that they were right, many scientists were confused by this information. According to Ben Santer of the Lawrence Livermore National Laboratory in California, “It is very difficult to understand physically how the lower troposphere could be cooling while the Earth’s surface and the middle and upper troposphere were warming, as the study found.”

Now, Carl Mears and Frank Wentz of Remote Sensing Systems in Santa Rosa, California, have found that satellite drift may be responsible for giving the impression that the troposphere is cooling. The satellite is supposed to take measurements at the same time every day while it passes over the equator. This was around 2 pm local time at first, but it was crossing the equator at 5 pm after two years. The fact that it is cooler at 5 pm than at 2 pm was biasing the results. Once a correction for satellite drift was made, the revised data showed that the troposphere is warming.

Weather balloon data has also showed a discrepancy with global warming models. However, Steven Sherwood of Yale University in New Haven, Connecticut, and his colleagues have shown that balloon measurements are also unreliable. Over the years, researchers developed new ways to shield temperature sensors from direct sunlight. However, they rarely bothered to make a note of this shielding, or calculate how it would affect raw data. Sherwood’s team found that improved shielding caused the sensors to record a drop in temperature, which can explain why weather balloons have recorded a trend of declining temperature in the troposphere.

Christy has reanalysed his data, using the information from Mears and Wentz’s study, and has found that the Earth is warming about 1.23ºC per century. Mears and Wentz have calculated that the Earth is warming at about 1.9ºC per century.

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