What Is the Hottest Year on Record? 1

Posted by Brad Johnson Fri, 10 Aug 2007 17:23:00 GMT

A story on Daily Tech yesterday, with the headline “Years of bad data corrected; 1998 no longer the warmest year on record”, was immediately picked up by Rush Limbaugh:
I’ve got a story here from Reuters that is embargoed until 2 o’clock. I’m tempted to break the embargo, but I probably won’t because I play by the rules. But the basic story – and I’m going to give you the details of this as the program unfolds – one of the central tenets 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.
and thence to dozens of conservative websites; Michelle Malkin has a helpful list of links to the dozens of websites repeating the story. Today New York Times’s Opinionator blog repeated the claim, calling the general scientific community “Cassandras”:
A blogger’s recalculation of NASA data puts 1934, not 1998, as the warmest year on record…. Among global warming Cassandras, the fact that 1998 was the “hottest year on record” has always been an article of faith.

These stories are grossly misleading. Steve McIntyre’s correction applied to the surface temperature record of the contiguous lower 48 United States, not the global mean surface temperature record. 19 of the hottest twenty years on record for the planet have come in the last 26 years. 2005 is the hottest year on record, not 1998 (number 2) or 1934 (number 64).

Correcting the US data record was genuine accomplishment by an individual blogger, but of no qualitative consequence.

Addendum It should be clear that everyone here is talking about surface air temperature anomaly figures, which are deviations from the mean temperature of the 30-year period of 1951-1980. These numbers are not absolute temperature. For more, see Hansen et al. 1999. The abstract from that paper shows how absurd the claim that McIntyre has rocked the scientific world is:
We describe the current GISS analysis of surface temperature change for the period 1880- 1999 based primarily on meteorological station measurements. The global surface temperature in 1998 was the warmest in the period of instrumental data. The rate of temperature change was higher in the past 25 years than at any previous time in the period of instrumental data. The warmth of 1998 was too large and pervasive to be fully accounted for by the recent El Nino. Despite cooling in the first half of 1999, we suggest that the mean global temperature, averaged over 2-3 years, has moved to a higher level, analogous to the increase that occurred in the late 1970s. Warming in the United States over the past 50 years has been smaller than in most of the world, and over that period there was a slight cooling trend in the eastern United States and the neighboring Atlantic Ocean. The spatial and temporal patterns of the temperature change suggest that more than one mechanism was involved in this regional cooling. The cooling trend in the United States, which began after the 1930s and is associated with ocean temperature change patterns, began to reverse after 1979. We suggest that further warming in the United States to a level rivaling the 1930s is likely in the next decade, but reliable prediction requires better understanding of decadal oscillations of ocean temperature.

Update See Real Climate and Media Matters for more.


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  1. Simon D Mon, 13 Aug 2007 13:50:42 GMT

    The distortion of this is I’m sure a frustration to many climate scientists. The US error alone is small; it is quite negligible when you look at the global average (the best analysis I’ve seen is at Open Mind). And even if the global 1998 data were wrong, it would not change the volumes of other evidence for the human role in observed warming or for projected warming in the future.