April 2015 Global Atmospheric Temperature

The University of Alabama at Huntsville (UAH) satellite global atmospheric temperature measurements show that April was slightly cooler than March. The March anomaly was O.14°C and April’s was 0.07°C. The UAH measurements confirm the “18+ years of no statistically significant evidence of global warming”. The chart (click to enlarge) shown below uses the new Version 6.0 dataset which replaces Version 5.6.


The managers of the UAH satellite program, Roy Spencer, John Christy and William Braswell have provided the procedures and codes for the change from Version 5.6 to 6.0 allowing for on-line critique of their work.

The Science and Energy Policy Project (SEPP) has summarized the reasoning behind the switch to the upgraded Version 6.0 as follows:

“Measurement Issues – Atmosphere: For over twenty-five years Roy Spencer and John Christy (University of Alabama in Huntsville (UAH)) have been monitoring global atmospheric temperatures using MSU/AMSU global satellites. The data starts in December 1978. Later joined by William Braswell, they are now undertaking the most extensive revision of the procedures and computer code they have used. The new set is termed as Version 6.0. The rationale for undertaking the change is that the calibration of the satellite instruments is not rock stable, over the years there have been channel failures, and that the satellite orbits change over time.

Another reason given is that data from the older MSU instruments were reasonable for calculating global average temperatures, the new AMSU instruments are superior for calculating regional variations in temperatures.

Rather than making the changes, then submitting them to a peer-reviewed journal for publication, a process that would take at least two years, the group has publically announced its proposed changes for public review, including on Roy Spencer’s web site. The announcement is considered a draft, subject to review, of what is being done. Appropriate suggestions are being considered.

The UAH satellite adjustments are empirically based adjustments, not climate-model based adjustments such as by Remote Sensing Systems (RSS). Interestingly, UAH data showed a shorter period of no warming (the pause or plateau) than the RSS data did. After the new adjustments, the new UAH dataset shows an eighteen-year pause, in line with the RSS dataset.

In addition, the new UAH adjustments lowers the trend for more recent temperatures – earlier temperatures have faster warming, similar with results from the RSS approach. Land areas show a greater warming decadal trend since 1979 than ocean areas, and both trends are weaker than thermometer-based trends

As with the past, the UAH team is a sterling example of transparency in scientific research. No doubt some will be critical of what the team is accomplishing and SEPP, for example, may disagree on how UAH calculates trends. But, the team provides an example of how science progresses.”

The satellites, UAH and RSS, are as close as one can get to global measurements versus the ground-based systems. The ground-based systems include only very limited actual temperature measurements of the oceans and far northern and southern parts of the land.


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