Ok, now this is classic.  Bloggers have now debunked the myth that 1998 was the hottest year on record:

My earlier column this week detailed the work of a volunteer team to assess problems with US temperature data used for climate modeling. One of these people is Steve McIntyre, who operates the site climateaudit.org. While inspecting historical temperature graphs, he noticed a strange discontinuity, or "jump" in many locations, all occurring around the time of January, 2000. 

These graphs were created by NASA’s Reto Ruedy and James Hansen (who shot to fame when he accused the administration of trying to censor his views on climate change). Hansen refused to provide McKintyre with the algorithm used to generate graph data, so McKintyre reverse-engineered it. The result appeared to be a Y2K bug in the handling of the raw data.

McKintyre notified the pair of the bug; Ruedy replied and acknowledged the problem as an "oversight" that would be fixed in the next data refresh.

NASA has now silently released corrected figures, and the changes are truly astounding. The warmest year on record is now 1934. 1998 (long trumpeted by the media as record-breaking) moves to second place.  1921 takes third. In fact, 5 of the 10 warmest years on record now all occur before World War II.  Anthony Watts has put the new data in chart form, along with a more detailed summary of the events. 

Guess someone just did.

Meanwhile go check out some of the comments left at Roger Pielke’s blog:

It appears that the historians busily re-writing history in the novel “1984″ have modern competition. Does the well-meaning possession of an agenda excuse such excess of professional scientists?

GISS may well have to adjust 2006 down a bit further [as Steve M observes, it’s only been adjusted down by 0.10 as compared to 0.15 for all other years].

As it stands, we are looking at a bladeless “Hockey Stick”, and for all intents and purposes at the falsification of the anthropogenic warming hypothesis for North America.

Of particular note is that the Climate Audit piece indicates that GISS has erased the old [unadjusted] data, giving it the makings of an excercise in covering one’s tracks. The legality of this must be questionable given that we are dealing a federally funded agency. Astounding.

Yesterday they completely overwrote their US data set, changing virtually every number prior to 2000, explaining this only with a cursory comment on their webpage. In addition, they have changed their UHI adjustments so that in many cases the changed UHI adjustments offset the error in their “raw” data.

Even before these change, I was unable to track their pre-2000 data to any archive. It was sort of like USHCN adjusted data in the 1990s but diverged in earlier periods. I’ve requested a copy of the original data set or information on its provenance.

I would welcome letters to GISS urging them to fully disclose their source code.

The unravelling of the GISS temperature story has only just begun and is bound to have repercussions. You can fool all of the people some of the time, some of the people all of the time, but not both. The non-scientific, professional press have been airing questions about the IPCC “science” for some time now, and the mainstream media are picking up on the fact that some things don’t smell all too good in the AGW/Climate Change larder.

And this great comment rounds up the timeframe of events:

The whole issue came up because of some photos Anthony Watts volunteers took of the Detroit Lakes, MN USHCN site in July.

http://gallery.surfacestations.org/main.php?g2_itemId=3891

Climate Audit first commented on the Detroit Lakes site on July 26th.

http://www.climateaudit.org/index.php?paged=3

The debate/discussion continued with a post at
http://rabett.blogspot.com/ on August 1st.

With a further look at the data, Steve McIntyre discovered the Y2K error and announced it on August 3rd.

http://www.climateaudit.org/index.php?paged=2

And NASA corrected it’s GISTEMP data on August 7th. I believe.

http://data.giss.nasa.gov/gistemp/

All happened very fast.

And this commenter explains why this change in data is so important:

the USA has been the single biggest source of CO2 emissions in the world over the past 100 years. We have for 20 years or so been asked to accept as the fundamental hypothesis the postulate that an increase in CO2 is the primary and single most important independant variable forcing increased temperatures. CO2 ppmv has continued to increase, temperatures have not. The hypothesis has been falsified for North America.

[…]The overarching question in all of this is: why have publicly funded research organizations [in the US, UK and elsewhere] been getting away with publishing increasingly questionable climate data that is turned into government policy as if gospel, without subjecting themselves the most basic of scientific scrutinies, that of publishing their respective “materials and methods” sections?

if CO2 is a so called greenhouse gas, it was supposed to force an increase in temperatures. This has not happened and is not happening. 1934, during the Depression and the ensuing economic downturn [= less use of hydrocarbons = less CO2] is the warmest year on record since 1900. There is no post-1998 Hockey Stick as forecast by the IPCC. The CO2 based AGW hypothesis has been falsified. Back to the drawing board.

The error noted by Steve M. was obvious, its source was obvious, and the fix was obvious. The keepers of the data could not argue against it and so they caved in and adjusted their data in less than a week. The fact that one error had such a profound impact on a key piece of hype that is used to push the need for drastic action should make everybody pause and wonder what the eventual outcome will be of the broader issues being looked at by Anthony Watts and his volunteer observers. What happens if there is another tenth of a degree (or more) taken out of the dataset by errors and biases uncovered there? Doesn’t that begin to call into question the whole theory of AGW? If the models can account for warming up to the 1950s with natural forcings, but not all of the warming since 1980, then what happens if that chunk of the post-1980s warming is found to be error or measurement artifacts? Will the experts admit that the models can account for all warming with natural forcings? Then what? The wheels fall off the Al Gore snake-oil-mobile…

For all who were sarcastic, etc., about that .1C. As pointed out that is 16.7% of a total phenomena claimed to be valid. Not only is it significant, considering that IPCC claimed that the correctness was about 99% and now part has been shown to be at best 83.3%, should cause an appreciation that potential (not actual) problems have been proven. The correction has falsified an important claim of at least the significance, if not the relation itself.

Crossposted from Flopping Aces