By Steve Goddard
h/t to reader “Phil.” who lead me to this discovery.
In a previous article, I discussed how UAH, RSS and HadCrut show 1998 to be the hottest year, while GISS shows 2010 and 2005 to be hotter.
But it wasn’t always like that. GISS used to show 1998 as 0.64 anomaly, which is higher than their current 2005 record of 0.61.
You can see this in Hansen’s graph below, which is dated August 25, 1999
But something “interesting” has happened to 1998 since then. It was given a demotion by GISS from 0.64 to 0.57.
The video below shows the changes.
Note that not only was 1998 demoted, but also many other years since 1975 – the start of Tamino’s “modern warming period.” By demoting 1998, they are now able to show a continuous warming trend from 1975 to the present – which RSS, UAH and Had Crut do not show.
Now, here is the real kicker. The graph below appends the post 2000 portion of the current GISS graph to the August 25, 1999 GISS graph. Warming ended in 1998, just as UAH, RSS and Had Crut show.
The image below superimposes Had Crut on the image above. Note that without the post-1999 gymnastics, GISS and Had Crut match quite closely, with warming ending in 1998.
Conclusion : GISS recently modified their pre-2000 historical data, and is now inconsistent with other temperature sets. GISS data now shows a steady warming from 1975-2010, which other data sets do not show. Had GISS not modified their historic data, they would still be consistent with other data sets and would not show warming post-1998. I’ll leave it to the readers to interpret further.
BTW – I know that you can download some of the GISS code and data, and somebody checked it out and said that they couldn’t find any problems with it. No need to post that again.