In August the 8th, 2009  the Goddard Institute for Space Studies analysis  of surface air temperature measurements reported  that the calendar year 2008 was the coolest year since 2000.

But don’t be fooled because, at present, measurements of surface air temperature are impossible to measure with scientific accuracy. Satellite data, on the other hand appears to be vastly superior scientifically speaking.

Recently, much scientific debate has focused on the global temperature of the Earth’s lower atmosphere as measured by orbiting satellites. And while these data are exceedingly precise, verified by multiple satellite observations, and balloon measurements taken in-situ, they reveal no discernible warming trend in the Earth’s lower atmosphere over the last 18+ years.

Dr. Roy W Spencer (NASA Marshall Space Flight Center) and Dr. John Christy (The University of Alabama in Huntsville) have used the Microwave Sounding Units (MSUs) flying aboard NOAA’s TIROS-N weather satellites to construct a continuous record of lower tropospheric (from the surface to about 4 miles) temperatures since the first MSU was launched in late 1978. The lower tropospheric temperature trend has been calculated to be -0.04 degrees C/decade.

In the March 13, 1997 edition of Nature, two scientists, James Hurrell and Kevin Trenberth, report that sea-surface temperatures monitored by buoys and ships at various locations in the tropics show, for the same period as the satellite record, a warming trend of +0.12 deg. C/decade, in apparent disagreement with the satellites. This so-called “disagreement” between satellite and surface temperature measurements is not new.

Despite the fact that Hurrell and Trenberth estimate of the temperature of the atmosphere through a simple linear regression model based only on the sea surface temperatures, and a global climate model simulation with the same sea surface temperatures but no stratospheric volcanic aerosols, while the MSU data actually measure the temperature of the free atmosphere, Hurrell and Trenberth conclude that the satellite data must be wrong.

However, the satellite data are in agreement with the data from weather balloon measurements.”There isn’t a problem with the measurements that we can find,” Spencer explained. “In fact, balloon measurements of the temperature in the same regions of the atmosphere we measure from space are in excellent agreement with the satellite results.” Dr. Christy explained further, “In particular, we’ve examined these two `breaks’ claimed by Hurrell and Trenberth. Even in these disputed intervals, we find excellent agreement between the two independent, direct atmospheric temperature measurements from balloons and satellites.”

The disagreement between satellites and surface-based thermometers, furthermore, is not geographically uniform. “Over Northern Hemisphere land areas, where the best surface thermometer data exist, the satellites and thermometers agree almost perfectly”, said Dr. Christy of UAH. “It is primarily over the oceans where they disagree by a couple of tenths of a degree C. This is most likely a well-known phenomenon in which the temperature in the deep atmosphere is not as strongly linked to the surface temperature as it is over land.”

So now you know the truth.

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