Analysis Of 23 Top Quality US Surface Stations Shows Insignificant Warming…Only 0.16°C Rise – Per Century!

Temperature Trends at First Class US Stations
By Ron Clutz

In a previous study of World Class station records, the effects of urban development could not be discounted since the 25 long service records come from European cities.  This is a study to see what the best sites in the US can tell us about temperature trends in the last century.

There are two principal findings below.

Stevenson_screen public domainSurfacestations.org provides a list of 23 stations that have the CRN#1 rating for the quality of the sites. I obtained the records from the latest GHCNv3 monthly qcu report, did my own data quality review, and built a Temperature Trend Analysis (TTA) workbook.

Photo: Public domain

Spread out across the USA

As it happens, the stations are spread out across the continental US (CONUS). NW: Oregon, North Dakota, Montana; SW: California, Nevada, Colorado, Texas; MW: Indiana, Missouri, Arkansas, Louisiana; NE: New York, Rhode Island, Pennsylvania; SE: Georgia, Alabama, Mississippi, Florida.

The records themselves vary in quality of coverage, but have all been included here because of their CRN#1 rating. The gold medal goes to Savannah for 100% monthly coverage, with a single missing daily observation since 1874.

Pensacola was a close second among the four stations with perfect monthly coverage. Most stations were missing less than 20 months with coverages above 95%.

Area  FIRST CLASS US STATIONS
History 1874 to 2013
Stations 23
Average Length 118 Years
Average Trend 0.16 °C/Century
Standard Deviation 0.66 °C/Century
Max Trend 1.18 °C/Century
Min Trend -1.93 °C/Century

Only 0.16°C rise per century

The average station shows a rise of about 0.16°C/century. The large deviation, and the fact that multiple stations had cooling rates, shows that warming has not been extreme, and varies considerably from place to place. The observed warming for this group is less than half the rate reported in the European study.

Temperature trends are local, not global

Most remarkable about these stations is the extensive local climate diversity that appears when station sites are relatively free of urban heat sources. 35% (8 of 23) of the stations reported cooling over the century. Indeed, if we remove the 8 warmest records, the rate flips from +0.16°C to -0.14°C.

And the multidecadal patterns of warming and cooling were quite variable from place to place. Averages over 30-year periods suggest how unusual these patterns are.

For the set of 23 stations the results are:

°C/Century Start End
+0.78 Start 1920
– 1.21 1921 1950
-1.11 1951 1980
+1.51 1981 2013
+0.99 1950 2013

The first period varied in length from each station’s beginning to 1920. Surprisingly the second period cooled in spite of the 1930s. Warming appears mostly since 1980.  As mentioned above, within these averages are many differing local patterns.

Conclusion:

Question: Is it warmer now than 100 years ago?
Answer: It depends upon where you live. The best observations from US stations show a barely noticeable average warming of 0.16°C/century. And 35% of stations showed cooling at the same time that others were warming more than the average.

Note about data quality.

Available is my workbook for Truman Dam & Reservoir as an example of my data quality review method.  There are sheets showing the incoming qcu values, removal of flags and errors, audit of outliers (values exceeding 2 St. Dev.) and CUSUM and 1st differences analyses to test for systemic bias. Note that Truman missed out entirely on warming from 1956 to 2002, in contrast to the conventional notion of global warming from the 1970s to 2000.

Truman Dam & Reservoir also provides a cautionary tale about temperature analysis.  The station’s annual averages appear to rise dramatically from 2003 to present. On closer inspection, that period is missing values for 6 Decembers, 8 Januarys and 5 Februarys. So the annual warming is mostly the result of missing data-points.

This shows why analyzing the temperatures themselves can be misleading. By relying only on the station’s monthly slopes, TTA analysis effectively places missing values on the trend line of the existing values.

Note about Fall et al. (2011).

This was the first study to use CRN 1 to 5 ratings to look at US temperature trends in relation to station siting quality. Much discussed at the time was the finding of CRN 1&2 showing warming of 0.155°C/decade for the period 1979 to 2008. The comparable finding from this analysis is 0.151°C/decade for CRN 1 stations.

Little noticed was Figure 10 on page 10 of Fall et al. That graph shows that CRN 1&2 rate of warming Tavg unadjusted was about 0.2°C/century for the period 1895 to 2008.  This analysis shows a comparable 0.16°C for CRN 1 for the same period up to 2013.

 

6 responses to “Analysis Of 23 Top Quality US Surface Stations Shows Insignificant Warming…Only 0.16°C Rise – Per Century!”

  1. jim

    I’m surprised they used Truman dam in Missouri. I wonder where the qualifier is? Couldn’t find it.only been there since the mid fifties. It’s the generator holdback so the lake of the Ozarks isn’t so variable in height. loth is the massive generator for ameren electric, and needs massive amounts of backfill to keep it operational. Truman varies greatly in height because of that. Its not because of flooding like everyone’s been told. Tempreture variation should be extreme because of that. I’d like to see that site. Right be like the one on other dams in Missouri. Where they claim non variable water levels. That’s be, air tempreture varies with the distance above the water level.

  2. BobW in NC

    Whoa! Wait a minute! In Table 1 (“Only 0.16°C rise per century”), am I reading the data correctly that the SD was 0.66° and the mean was 0.16° rise/century? In other words, the SD was roughly five times the mean value? What is the standard error of the mean, then? It must be huge.

    If I remember my statistics correctly (50+ years ago and I may not), that magnitude of a SD would render the TREND showing a RISE in temperature meaningless in that regard.

    It would also be interesting to run a 95% Confidence Interval on those data, because it gives you the limit values that contain sigma, the “true” mean. For the moment, my hypothesis is that there is no rise in temperature shown by those data.

    And only 23 CERN 1 stations out of the 1200+ in the US.

    Great job in amassing and analyzing these data, Pierre! AS always, thanks!

  3. Ron C.

    Thanks for posting this, Pierre.

    Here is a direct link to the stations with CRN ratings.

    http://www.surfacestations.org/USHCN_stationlist.htm

    1. DirkH

      Great work! Thanks!

      The warmists hate to look at single stations because those will just not deliver what the theory wants…

  4. Mindert Eiting

    Thanks, Ron and Pierre. Ron, if you have time, could you repeat this study for 23 bottom quality stations in the USA and compare the results? Note that a basic requirement of objective measurement is a positive correlation of items. Here we see that with high quality stations trends go in opposite directions. So it depends on the subjective choice of stations what the global USA trend will be. BobW: with random sampling, standard error of the mean equals standard deviation divided by sqr sample size. The rise would then be slightly more than one standard error (some would call this insignificant).