Update by Kip Hansen

Last week I wrote about UCAR/NCAR’s very interesting discussion on “What is the average global temperature now?”.

Part of that discussion revolved around the question of why current practitioners of Climate Science insist on using Temperature Anomalies — the difference between the current average temperature of a station, region, nation, or the globe and its long-term, 30-year base period, average — instead of simply showing us a graph of the Absolute Global Average Temperature in degrees Fahrenheit or Celsius or Kelvin.

Gavin Schmidt, Director of the NASA Goddard Institute for Space Studies (GISS) in New York, and co-founder of the award winning climate science blog RealClimate, has come to our rescue to help us sort this out.

In a recent blog essay at RealClimate titled “Observations, Reanalyses and the Elusive Absolute Global Mean Temperature”, Dr. Schmidt gives us the real answer to this difficult question:

“But think about what happens when we try and estimate the absolute global mean temperature for, say, 2016. The climatology for 1981-2010 is 287.4±0.5K, and the anomaly for 2016 is (from GISTEMP w.r.t. that baseline) 0.56±0.05ºC. So our estimate for the absolute value is (using the first rule shown above) is 287.96±0.502K, and then using the second [the first and second rules have to do with estimating the uncertainties – see Gavin’s post], that reduces to 288.0±0.5K [2016]. The same approach for 2015 gives 287.8±0.5K, and for 2014 it is 287.7±0.5K. All of which appear to be the same within the uncertainty. Thus we lose the ability to judge which year was the warmest if we only look at the absolute numbers.”

You see, as Dr. Schmidt carefully explains for us non-climate-scientists, if they use Absolute Temperatures the recent years are all the same — no way to say this year is the warmest ever — and, of course, that just won’t do — not in “RealClimate Science”.

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Author’s Comment Policy:

Same as always — and again, this is intended just as it sounds — a little tongue-in-cheek but serious as to the point being made.

Readers not sure why I make this point might read my more general earlier post:  What Are They Really Counting?

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