Well, it turns out, according to the NASA GISS database, that 1998 was not even the hottest year of the last century. This is because many temperatures from recent decades that appeared to show substantial warming have been revised downwards. Here is how that happened (if you want to skip the story, make sure to look at the numbers at the bottom).
One of the most cited and used historical surface temperature databases is that of NASA/Goddard’s GISS. This is not some weird skeptics site. It is considered one of the premier world temperature data bases, and it is maintained by anthropogenic global warming true believers. It has consistently shown more warming than any other data base, and is thus a favorite source for folks like Al Gore. These GISS readings in the US rely mainly on the US Historical Climate Network (USHCN) which is a network of about 1000 weather stations taking temperatures, a number of which have been in place for over 100 years.
Anyway, McIntyre suspected that one of these adjustments had a bug, and had had this bug for years. Unfortunately, it was hard to prove. Why? Well, that highlights one of the great travesties of climate science. Government scientists using taxpayer money to develop the GISS temperature data base at taxpayer expense refuse to publicly release their temperature adjustment algorithms or software (In much the same way Michael Mann refused to release the details for scrutiny of his methodology behind the hockey stick). Using the data, though, McIntyre made a compelling case that the GISS data base had systematic discontinuities that bore all the hallmarks of a software bug.
Today, the GISS admitted that McIntyre was correct, and has started to republish its data with the bug fixed. And the numbers are changing a lot. Before today, GISS would have said 1998 was the hottest year on record (Mann, remember, said with up to 99% certainty it was the hottest year in 1000 years) and that 2006 was the second hottest. Well, no more. Here are the new rankings for the 10 hottest years in the US, starting with #1:
1934, 1998, 1921, 2006, 1931, 1999, 1953, 1990, 1938, 1939
Three of the top 10 are in the last decade. Four of the top ten are in the 1930′s, before either the IPCC or the GISS really think man had any discernible impact on temperatures. Here is the chart for all the years in the data base.
1998 used to be considered the hottest year in “1000 years”. It’s now at number two behind 1934. 2001 was the eighth – it’s not even in the top ten anymore. 2006 wasn’t as hot as 1998. 1934 was the hottest year in not only the last 100 years, but as far back as NASA can find.