Watts Up With That? | March 24, 2014
Foreword by Anthony Watts
An essay by Monckton of Brenchley follows, but I wanted to bring this graphic from Dr. Mann’s recent Scientific American article to attention first. In the infamous “hide the decline” episode revealed by Climategate surrounding the modern day ending portion of the “hockey stick”, Mann has been accused of using “Mike’s Nature Trick” to hide the decline in modern (proxy) temperatures by adding on the surface record. In this case, the little white line from his SciAm graphic shows how “the pause” is labeled a “faux pause”, (a little play on words) and how the pause is elevated above past surface temperatures.
Source: http://www.scientificamerican.com/sciam/assets/Image/articles/earth-will-cross-the-climate-danger-threshold-by-2036_large.jpg
Looking at the SciAm graphic (see zoom at right), something didn’t seem right, especially since there doesn’t seem to be any citation given for what the temperature dataset used was. And oddly, the graphic shows Mann’s little white line peaking significantly warmer that the 1998 super El Niño, and showing the current temperature equal to 1998, which doesn’t make any sense.
So, over the weekend I asked Willis Eschenbach to use his “graph digitizer” tool (which he has used before) to turn Mann’s little white line into numerical data, and he happily obliged.
Here is the result when Mann’s little white line is compared and matched to two well known surface temperature anomaly datasets:
What is most interesting is that Mann’s “white line” shows a notable difference during the “pause” from HadCRUT4 and GISS LOTI. Why would our modern era of “the pause” be the only place where a significant divergence exists? It’s like “hide the decline” deja vu.
The digitized Mann’s white line data is available here: Manns_white_line_digitized.(.xlsx)
As of this writing, we don’t know what dataset was used to create Mann’s white line of surface temperature anomaly, or the base period used. On the SciAm graphic it simply says “Source: Michael E. Mann” on the lower right.
It isn’t GISS land ocean temperature index (LOTI), that starts in 1880. And it doesn’t appear to be HadCRUT4 either. Maybe it is BEST but not using the data going back to 1750? But that isn’t likely either, since BEST pretty much matches the other datasets, and in Mann’s graphic above, which peaks out at above 1°C, none of those hit higher than 0.7°C. What’s up with that? … continue
