Editor’s note: Today we welcome guest blogger Chapter 1.
“The only thing Antwan ever touched of mine was my hand, when he shook it at my wedding… But when you little scamps get together, you’re worse than a sewing circle.” Mia Wallace in Pulp Fiction
This diary follows a rumor’s spread through the conservative blogosphere. It begins with a story about how a persistent conservative blogger found a minor (but genuine) error in a NASA dataset, and how that error was promptly acknowledged and corrected. This story was told by the original blogger a few days ago, and then retold by other bloggers (with improvements) and again by other bloggers (with more improvements).
By yesterday, we could read on A-List conservative blogs that “global warming hype” is largely derived from a Y2K bug, that the the new information is being suppressed by the media, and that someone had possibly launched an attack on the original blogger’s web site to prevent the truth from getting out.
We’ll start at the beginning by looking at the underlying science; what the error was, and why it matters. And we’ll see how that science got lost in successive retellings, even as sensational (but false) details were added.
US Temperature Records
Various government agencies have been keeping temperature records on a large portion of the country since about 1880. In principle, one can examine these records to see if the country is getting warmer. However, there are all sorts of complicating factors.
For one thing, you have to properly account for the Urban Heat Island affect– cities get warmer as more concrete and buildings appear for reasons unrelated to Global Warming. This issue is explained in detail here.
And there can also be problems in with instruments. As Gavin Schmidt wrote yesterday on RealClimate
Last Saturday, Steve McIntyre wrote an email to NASA GISS pointing out that for some North American stations in the GISTEMP analysis, there was an odd jump in going from 1999 to 2000. On Monday, the people who work on the temperature analysis (not me), looked into it and found that this coincided with the switch between two sources of US temperature data. There had been a faulty assumption that these two sources matched, but that turned out not to be the case. There were in fact a number of small offsets (of both sign) between the same stations in the two different data sets. The obvious fix was to make an adjustment based on a period of overlap so that these offsets disappear.
This was duly done by Tuesday, an email thanking McIntyre was sent and the data analysis (which had been due in any case for the processing of the July numbers) was updated accordingly along with an acknowledgment to McIntyre and update of the methodology.
The net effect of the change was to reduce mean US anomalies by about 0.15 ÂºC for the years 2000-2006. There were some very minor knock on effects in earlier years due to the GISTEMP adjustments for rural vs. urban trends. In the global or hemispheric mean, the differences were imperceptible (since the US is only a small fraction of the global area).
Got it? Let’s review:
First, NASA sent McIntyre an email thanking him and publicly acknowledged the issue (their web site says “We wish to thank Stephen McIntyre for bringing to our attention that such an adjustment is necessary to prevent creating an artificial jump in year 2000.”)
Second, small problems were found in comparing pre-2000 and post-2000 datasets. These changed post-2000 temperatures by about .15 degrees, and pre-2000 temps by much less.
Following is a graph of the 11 warmest years (data source is here) using the old (red) and yellow (new) temperature records. (I only show the data for these years because I couldn’t find the old data for the other years.)
Third, although its not obvious from the above graph which cherry-picks the warmest years, the graph continues to have a strong upload slope. You can see the original here (scroll down)
Fourth, this only affected the US temperature data, not the rest of the world. If you want to see worldwide temperatures over the rest of the world, look at the graphs presented here.
Finally, and perhaps most importantly, changes in US temperatures are only a small part of the reason we believe the world is getting warmer. The US only covers ~3% of the globe, so the other 97% is kind of important, too. Also, there is a tremendous amount of other evidence– direct satellite measurements, isotope studies from frozen bubbles of ancient air, evidence from fossilized vegetation, tree-ring studies, coral-growth studies, evidence from former location of coastlines, etc. etc.
Steve apparently details his experience and correspondence on his blog, climateaudit.org. I say “apparently”, because his blog has been inaccessible for over 24 hours, meaning that neither I nor any other blogger can verify his story.
On August 9th, Bill Hobbs wrote a post at Ecotality entitled “Oops!”
NASAâ€™s much-ballyhooed data showing that 1998 was the warmest year on record for the Earth was, uh, wrong. A blogger found a Y2K bug in the data algorithm, NASA climatologist James Hansen, and NASA has now issued corrected data. The warmest year on record for the Earth: 1934 – 1998 was the second-warmest. The third warmest: 1921. Michael Asher at DailyTech.com tells the story of how blogger Steve McIntyre, who operates the site climateaudit.org, found the error and forced NASA to admit it.
This passage contains several errors. As noted, the data set is for the US, not the Earth. Although the error did involve datasets that began and ended in 2000, I haven’t seen any evidence that the data was a “Y2K bug.” Most of the the zillions of bugs in zillions of lines of code written or used in the year 2000 had nothing to do with Y2K.
Both the old and new datasets show a generally upward trend (although with a bump during the dustbowl years), and both plots are nearly the same. But instead of mentioning that, Hobbs chose to emphasize that 1934 now appeared warmer than 1998. He did not mention anywhere that before the revisions, 1998 had been in a statistical tie with 1934 (+1.24 degrees vs +1.23). After the revisions, it still was (+1.23 vs +1.25). (To see this graphically, scroll up again to the graph– you won’t be able to tell the difference between 1934 and 1998 without a magnifying glass– before or after the revision.
Michael Asher noted that,
after the revision, 5 of the 10 warmest years on record now all occur before World War II.
Unfortunately, he didn’t note that before the revision, 4 of the 10 warmest years occurred before World War II. In fact, only 1 year dropped out of the top ten because of the revisions.
Off to the races
The story began rapidly spreading through the conservative blogosphere. In most tellings, it contained the following elements:
a) NASA was forced to admit an error. (Truth: NASA promptly corrected the error and acknowledged it)
b) The revised data were dramatically different than the unrevised data (false)
c) The error was a Y2K bug (I can’t confirm or refute this, but I doubt it)
d) The uncorrected data were a big part of the case for global warming (wildly false. As noted, worldwide temperature records are far more important. And direct temp measurements are only a part of the reason we think the world is warming.)
e) The Mainstream media are burying the story (Er, there isn’t a story to report)
This is how it appeared in the Wall Street Journal’s Best of the Web Today blog.
Global Warming Is a Hoax*
Now it turns out that there was a Y2K bug–and it contributed to global warming hype. Michael Asher of DailyTech.com has the story…
This almost sounds too good to be true: The one Y2K bug that happened to slip through was the one that contributed to another alarmist narrative. But when you think about it, it makes sense. NASA’s faulty findings didn’t look faulty to global warmists, who saw exactly what they were expecting to see…
*But Y2K turns out to have a kernel of truth.
ACE WONDERS WHY NOBODY’S TALKING ABOUT the NASA climate data revision.
UPDATE: Well, here’s a bit of notice.
ANOTHER UPDATE: More here: “Will the mainstream media report the corrected story with as much gusto as they initially reported the claim that 1998 was the warmest on record? Doubtful. But they should. Good public policy can not be made on bad data.”
MORE: This comment at Ecotality distinguishes hottest years in America from hottest years globally, but I always understood this to be about American, not global, records. And I think I was right…
Plus, reports of Denial-of-Service attacks.
Some big environmental news that you havenâ€™t heard much about: NASA has revised much-publicized US temperature data that have been used to claim 1998 as a record-breaking hottest year in the millenium.
(Does Michelle Malkin really believe that NASA has been recording US temperature data for a millenium? Really?)
It even found its way to a comment on a rec-listed diary.
You’re all over-reacting as usual. (0 / 0)
Stop scaring your damn kids.
The other development today was that a lot of the data generated for US temperatures was off by a rather large percentage(in a good way) due to a stupid Y2k bug. Apparently there was a similar temperature increase trend in the 30’s that went away, hell if I know what any of this means, but chances are neither do you.
I’ve taken enough of your time already without going through the many things wrong with these. It (probably) wasn’t a Y2K bug. The revisions have very little affect on the temperature record for the US. The temperature record for the US is a very small part of the reason why we believe the world is warming.
And then Rush picked it up.
One of the central tenants of the global warming hoaxers today is that 1998 was the hottest year in history on record. And that five of the top ten hottest years have been in the last ten years. Five of the hottest years have been in the last ten. It turns out that the statistics, the temperature data that NASA used to compile the temperatures in 1998 is wrong. 1998 was not the hottest year on record. 1934 was. In fact, five of the top ten, I believe, I’m going to have to check this, five of the top ten warmest years on record are in the 30s, during the Dust Bowl era and so forth.
In fact, this Reuters story talks about how global warming is going to be off the charts starting in 2009 and in this story they actually say that the global warming scientists are really frightened now because 2009 is going to just blow 1998 out of the water in terms of breaking records, and 1998 is now shown to be not true. A blogger discovered this. I’ll give you the details as the program unfolds today in a more, shall I say, systematic way. The thing to remember is that 1998 is not the warmest year on record. It forms one of the central theses about the current global warming hoax.
Rush probably has a far bigger audience than everyone else I’ve cited put together. So this is the version that will enter the public record.
The Sewing Circle Blogosphere
I can’t tell you how many times I’ve followed links on an Instapundit story back to its source and seen how Instapundit’s telling of the story bears no resemblance to the original. This appears to be a widespread phenomenon on the right.
All blogs will cite other blogs for clever opinions or turns of phrase. And these do get more extreme as they travel along. But it seems to me that only right-wing blogs cite other right-wing blogs for basic facts.
I suspect this happens in part because of differences in blog design. If I want to comment on an arctic ice loss diary, I will do so in the comments. And the game of telephone ends there because no other blog will cite my comment as a source of factual information. By contrast, many right-wing blogs don’t have comments– so someone who wants to comment on blog X must do so as a post on blog Y– and it would be rude to simply ignore blog X, so you retell blog X’s point (with improvements). Then blog Z comments on blog Y (but it would be rude to cite blog X, when the story came from blog Y), and the story grows a bit with the next retelling.
There are other, less charitable explanations involving intellectual integrity, but I won’t go there. Whatever reason, this example illustrates that the right-wingers don’t have a self-correcting blogosphere. They have a Sewing Circle Blogosphere.