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Comparing all the temperature records

Posted on 23 December 2010 by John Cook

I've added a new graphic to the list of Hi-rez Climate Graphics: a composite of all the major global temperature records, going back to 1890 (obviously the satellite records only begin in the late 20th century). Many thanks to Benjamin Franz who sent me the spreadsheet of all the data:

Benjamin has published a series of useful graphs including a version of the graph above. The data comes from surface temperature measurements of NASA GISS, HadCRUT, NOAA plus the satellite measurements of lower atmosphere temperature by RSS and UAH. The data was originally compiled by Kelly O'Day from Climate Charts and Graphs who put all 5 datasets into a single spreadsheet. The problem is all the different temperature records use different base periods.

Temperature records are expressed as an anomaly (or variation) from a specified base period. For example, the base period for both satellite recoreds (UAH and RSS) is 1979 to 1998. So for example, when the UAH record says 0.5°C, it actually means the temperature is 0.5°C warmer than the average temperature over 1979 to 1998. The GISS base period is 1951 to 1980. HadCRUT use the base period 1961 to 1990. NOAA use 1971 to 2000. The choice of base period doesn't really matter as its the trend that's important, not the absolute values. Nevertheless, some people do get a little confused when comparing two temperature records that use different base periods.

To get around the problem of different base periods, Benjamin normalised all the datasets by calculating each temperature record's average value over the period 1980 to 2010. Then he calculated the temperature anomaly from the 1980 to 2010 base period. Thus each record now used the same base period and could be directly compared.

As surface temperature is a noisy signal, with plenty of variation from year to year, Benjamin calculated the long-term trend by calculating the 133 month moving average. That is what is shown in the graph above. The graph is also available in a number of formats:

Now I would love to add the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis to this graph. The ECMWF record covers the full globe but uses an independent technique to NASA to estimate warming in the Arctic regions. Their data is available on their website but I've never been able to penetrate their obtuse interface (no offence to the good folk at the ECMWF). So if anyone is able to post a link to the pertinent data or even better, hand it to me on a silver platter in Excel format (hint, hint), please be my guest :-)

P.S. - for a more rigorous treatment of this subject, Tamino at Open Mind has two recent blog posts worth a look: Odd Man Out and Comparing Temperature Data Sets.

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Comments 51 to 54 out of 54:

dhogaza at 01:48 AM on 29 December, 2010
"Thank you for pointing out how insignificant my "longest cold spell" is! I had a hunch about that when I wrote it. But the long heat spell this year around Moscow, was very significant, as we all know." Significant, how? As "proof of global warming"? No, but it falls into a lengthening trend of extreme high temperature events being much more frequent as extreme low events. This is exactly the pattern of extreme events one would expect in a warming world. And, it was a much rarer event than your cold spell, as Russian meteorologists have described it as "unprecedented" - proxy reconstructions going back 1,000 years show nothing at all like the month long heat wave. Also, while Stockholm has been cold, it's been raining in the capital of Greenland, and ice in Hudson's Bay has been melting, resulting in exceptionally low sea ice extent in the Arctic at the moment: http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png
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muoncounter at 02:12 AM on 29 December, 2010
#49: "I was talking about a bias ... " Apparently a 'bias' that is in the eye of the beholder. I did not say anything questioning the value of your "longest cold spell"; I merely said that I was sure that you understood the importance of using significant measures as valid discussion points. If anything, the most common bias here is against making judgments on the basis of too few data points. We just don't like cherries and those who pick 'em are suspect.
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gallopingcamel at 17:31 PM on 29 December, 2010
dhogaza (@51), You said: "And, it was a much rarer event than your cold spell, as Russian meteorologists have described it as "unprecedented" - proxy reconstructions going back 1,000 years show nothing at all like the month long heat wave." You may be right, but proxy reconstructions fall far short of what the historical record can tell us. The years 1538 to 1541 were remarkable owing to the extremely hot summers throughout Europe. There were periods of 7 months or more with extreme heat. It was possible to wade across the river Seine in Paris. While London experienced very hot summers over this period, the river Thames froze in 1506, something that has not happened since 1814. Here is a link that you may find interesting: http://booty.org.uk/booty.weather/climate/1500_1599.htm
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D Kelly O at 03:01 AM on 7 January, 2011
John Glad to see you using my consolidated anomaly data file. I've just posted a "how to" on developing a common baseline for the 5 major anomaly series ( link). The RClimate script lets users compare 2 series with a trend chart and xy scatter plot. I have added combined baseline csv file to my on-line data files so that citizen scientists can directly compare the series using a common baseline (link )
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