GISS Adjustments Since 2008

By Paul Homewood

Following the pause busting adjustments made by RSS, we need to keep in mind how GISS have been up to the same tricks for years.

Last year, of course, they instituted the same massive set of adjustments that NOAA had done, following Thomas Karl’s efforts. However, although these were by far the largest ones, in recent years other adjustments had been made, gradually cooling the past and warming the present.

One of the problems in trying to keep track is that, unlike RSS, they don’t archive old data. Also, because they only report anomalies, it is impossibly to identify which years have been adjusted in absolute terms.

Fortunately, bloggers have been archiving their own GISS records, and we also have the Wayback Machine, so we can piece together some of the recent alterations.

First, let’s take the GISS LOTI dataset produced for April 2008, as archived by Climate4You here, and compare with the current version here.

We see in the latest version that the past has been cooled, particularly the 1930s, and recent decades warmed.

But let’s now take a closer look at the recent period since 1998.

We have the pre-Karlised version from February 2015 archived in the Wayback Machine here.

If we compare this with the latest Karlised version, an extra 0.05C has been added to 2014 anomalies, when compared with 1998. The actual anomalies are shown in Appendix A, but, as an example, in the old version 2014 was 0.06C warmer than 1998, but in the new 0.11C warmer – in other words an extra 0.05C.

However, the Feb 2015 version had itself been adjusted in comparison with the 2008 one. We can see below that by 2007 an extra 0.01C was being added on, relative to 1998.

These may only be small amounts, but cumulatively they gradually add up, and over such a short period of time can be quite significant.

Also we don’t know what other changes took place prior to 2008, or what 2014 would have looked like if the 2008 methodology was still being used.

But if we add the 0.01C adjustment. made between the 2008 to 2015 versions, to the 2014 discrepancy of 0.05C, we get a total of 0.06C. This is more than half of the claimed increase from 1998 to 2014.

APPENDIX A – GISS LOTI Anomalies (Hundredths of Degree C)

Current Version 2008 Version 2015 1998 63 57 61 1999 41 33 40 2000 42 33 40 2001 54 48 53 2002 62 56 61 2003 61 55 60 2004 54 48 51 2005 68 62 66 2006 63 54 59 2007 65 57 62 2008 53 49 2009 64 59 2010 71 66 2011 59 55 2012 62 57 2013 65 60 2014 74 67