Guest Post By Walter Dnes:

There have been various comments recently about GISS’ “dancing data”, and it just so happens that as GISS data is updated monthly, I’ve been downloading it monthly since 2008. In addition, I’ve captured some older versions via “The Wayback Machine“. Between those 2 sources, I have 94 monthly downloads between August 2005 and May 2014, but there are somegaps in the 2006 and 2007 downloads. Below is my analysis of the data.

Data notes

I´ve focused on the data to August 2005, in order to try to make this an apples-to-apples comparison. The net adjustments between the August 2005 download and the May 2014 download (i.e. the earliest and latest available data). I originally treated 1910-2005 as one long segment (the shaft of the “hockey-stick”). Later, I broke that portion into 5 separate periods. A month-by-month comparison of slopes of various portions of the data, obtained from each download.

Those of you who wish to work with the data yourselves can download this zip file, which unzips as directory “work”. Please read the file “work/readme.txt” for instructions on how to use the data.

GISS lists its reasons for adjustments at two webpages: This page lists updates from 2003 to June 2011. It is in chronological order is from the top of the page downwards. This page lists more recent updates, up to the present. It is in chronological order is from the bottom of the page upwards.

The situation with USHCN data, as summarized in Anthony´s recent article , may affect the GISS results, as GISS global anomaly uses data from various sources including USHCN.

In the graph below, the blue dots are the differences in hundredths of a degree C for the same months between GISS data as of May 2014 versus GISS data as of August 2009. GISS provides data as an integer representing hundredths of a degree C. The blue (1880-1909) and red (1910-2005) lines show the slope of the adjustments for the corresponding periods. Hundredths of a degree per year equal degrees per century. The slopes of the GISS adjustments are…

1880-1909 -0.520 C degree per century

1910-2005 +0.190 C degree per century

The next graph is similar to the above, except that the analysis is more granular, i.e. 1910-2005 is broken up into 5 smaller periods. The slopes of the GISS adjustments are…

1880-1909 -0.520 C degree per century

1910-1919 +0.732 C degree per century

1920-1939 +0.222 C degree per century

1940-1949 -1.129 C degree per century

1950-1979 +0.283 C degree per century

1980-2005 +0.110 C degree per century

The next graph shows the slopes (not adjustments) for the 6 periods listed above on a month-by-month basis, from the 94 monthly downloads in my possession.

1880-1909 ; dark blue; From August 2005 through December 2009, the GISS data showed a slope of -0.1 C degree/century for 1880-1909. From January 2010 through October 2011, the GISS data showed a slope between +0.05 and +0.1 C degree/century for 1880-1909. From November 2011 through November 2012, the GISS data showed a slope around zero for 1880-1909. From December 2012 through latest (May 2014), the GISS data showed a slope around -0.6 to -0.65 C degree per/century for 1880-1909.

; dark blue; 1910-1919 ; pink; From August 2005 through December 2008, the GISS data showed a slope of 0.7 C degree/century for 1910-1919. From January 2009 through December 2011, the GISS data showed a slope between +0.55 and +0.6 C degree/century for 1910-1919. From January 2012 through November 2012, the GISS data showed a slope bouncing around between +0.6 and +0.9 C degree/century for 1910-1919. From December 2012 through latest (May 2014), the GISS data showed a slope around 1.4 to 1.5 C degree per/century for 1910-1919.

; pink; 1920-1939 ; orange; From August 2005 through December 2005, the GISS data showed a slope between +1.15 and +1.2 C degree/century for 1920-1939. From May 2006 through November 2011, the GISS data showed a slope of +1.3 C degree/century for 1920-1939. From December 2011 through November 2012, the GISS data showed a slope around +1.25 C degree/century for 1880-1909. From December 2012 through latest (May 2014), the GISS data showed a slope around +1.4 C degree per/century for 1880-1909.

; orange; 1940-1949 ; green; From August 2005 through December 2005, the GISS data showed a slope between -1.25 and -1.3 C degree/century for 1940-1949. From May 2006 through December 2009, the GISS data showed a slope between -1.65 and -1.7 C degree/century for 1940-1949. From January 2010 through November 2011, the GISS data showed a slope around -1.6 C degree/century for 1940-1949. From December 2011 through November 2012, the GISS data showed a slope bouncing around between -1.6 to -1.7 C degree/century for 1940-1949. From December 2012 through latest (May 2014), the GISS data showed a slope bouncing around between -2.35 to -2.45 C degree per/century for 1940-1949.

; green; 1950-1979 ; purple; From August 2005 through October 2011, the GISS data showed a slope between +0.1 and +0.15 C degree/century for 1950-1979. From November 2011 through November 2012, the GISS data showed a slope bouncing around between +0.2 and +0.3 C degree/century for 1950-1979. From December 2012 through latest (May 2014), the GISS data showed a slope around +0.4 C degree per/century for 1950-1979.

; purple; 1980-2005 ; brown; From August 2005 through November 2012, the GISS data showed a slope of +1.65 C degree/century for 1980-2005. From December 2012 through latest (May 2014), the GISS data showed a slope around +1.75 to +1.8 C degree per/century for 1980-2005.

; brown; 1910-2005 ; red; This is a grand summary. From August 2005 through December 2005, the GISS data showed a slope of +0.6 C degree/century for 1910-2005. From May 2006 through December 2011, the GISS data showed a slope of +0.65 C degree/century for 1910-2005. From January 2012 through November 2012, the GISS data showed a slope bouncing around +0.65 to +0.7 C degree/century for 1910-2005. From December 2012 through latest (May 2014), the GISS data showed a slope of +0.8 C degree per/century for 1980-2005. In 7 years (December 2005 to December 2012), the rate of temperature rise for 1910-2005 has been adjusted up from +0.6 to +0.8 degree per century, an increase of approximately 30%.

; red;

Commentary

It would be interesting to see what the data looked like further back in time. Does anyone have GISS versions that predate 2005? Can someone inquire with GISS to see if they have copies (digital or paper) going further back? Have there been any versions published in scientific papers prior to 2005?

Given how much the data has changed in the past 9 years, what might it be like 9 years from now? Can we trust it enough to make multi-billion dollar economic decisions based on it? I find it reminiscent of George Orwell’s “1984” where;

“Winston Smith works as a clerk in the Records Department of the Ministry of Truth, where his job is to rewrite historical documents so they match the constantly changing current party line.”

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