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Temperature Data Still Riddled With Errors.



Temperature Data Still Riddled With Errors.

On Point No. 17

With the evidence for man-made global warming becoming more tenuous each year, green activists like Vice President Al Gore have been reduced to the environmental equivalent of ambulance chasing. Every notable weather event and every temperature anomaly, whatever the cause, is linked to man-made global warming. Such behavior denotes desperation and a willingness to say anything to promote the global warming agenda.

Summer has passed, and once again, Vice President Al Gore made an appearance to tell us that it was the hottest one ever. "The trend is up, and it will keep going up," said Gore. His figures are provided by the National Climatic Data Center – the NCDC is the record-keeping division of the Commerce Department’s National Oceanographic and Atmospheric Administration. They show that August’s global average temperature was 61.4 degrees Fahrenheit. According to the NCDC, the previous August record was set in 1997 at 61.1 degrees F.

Furthermore, according to the surface temperature record, 1997 was the hottest year in the last century, and 1998 is shaping up to be even warmer. El Niño is the most plausible scientific explanation for the recent temperature spike, which deflates Gore’s rhetoric, but there is also reason to be skeptical of the long-term temperature trend being observed in the surface-based, as opposed to satellite-based, record.

Developed for Political Impact. The temperature data that the Vice President relies on has never been peer-reviewed. The un-refereed material was "developed for political impact" by the NCDC, according to University of Virginia climatologist Patrick Michaels. An e-mail distributed by the NCDC admits, "our methodology was not documented in the open refereed literature," and states that "This [memorandum] is an attempt to provide documentation."

The data cited, says Michaels, is not a record of global temperatures, but rather an "index" combining three different measures. These measures include land surface temperatures, sea surface temperatures taken from ships, and temperatures taken from a network of buoys deployed in the 1980s. The sea surface temperatures were adjusted upward by 25 percent after 1982 in order to calibrate it with land surface temperatures. The result of this unorthodox adjustment is that recent years appear warmer in "indexed" terms.

Hot Times in Sacramento. The hype over record setting temperatures may also have more to do with the location of thermometers than with man-made global warming. Sacramento, California, for example, experienced a record 16 days of 100-degree plus temperatures, but it turns out that Sacramento’s temperatures were probably a lot cooler than thermometer readings showed. According to Channel 13 (KVOR) meteorologist Tom Loffman, "the National Weather Service has its thermometer on a roof where the sun hits and makes it too hot. I’ve been pestering those people for years with little success." The NWS is finally going to move the thermometer to a different location, leading Loffman to predict that "next year there won’t be any more record highs."

Roger Papas, an NWS meteorologist agrees. The rooftop is "not a good place," he said. "It’s particularly bad because there’s a tar roof, and where [the thermometer] sits there’s like a penthouse structure near it."

"One thing I find a little suspicious is that in the seven years I’ve been in Sacramento there have been maybe 30 record highs and no record lows," adds Mark Finan, chief meteorologist at Channel 3 (KCRA). "It stays so much warmer in the downtown area, you’re not going to get record lows. If we do get a cold snap this winter, we might set some records."

Those who study weather and track the earth’s temperature are well aware of this phenomenon, known as the urban heat-island effect. As cities grow they become warmer because vegetation is replaced with asphalt, concrete and steel, which effectively absorb and retain heat. Temperature records that have been taken from thermometers located in cities will display a false warming trend over time. Attempts to remove this bias have been made, but there will always be some bias in the record.

San Francisco Bias. Apparently, Sacramento isn’t the only city with poorly located temperature gauges. A similar move in San Francisco lowered temperature readings considerably, and the NWS has just ordered all rooftop sites to be move to "more representative locations." Just how many rooftop sites exist is unclear.

What is becoming increasingly clear, however, is that the surface temperature record is greatly flawed, which casts doubt on claims that the earth is warming up. Until these many deficiencies are remedied, we should remain skeptical of claims from global warming activists.


Paul J. Georgia ( is a Research Associate at CEI.I


1Randolph E. Schmid, "August Sets High Temperature Record," The Associated Press, September 11, 1998.2Id.3"Hot air vs. warm temperatures," The Washington Times, August 31, 1998.4Id.5Dan Vierra, "The big cooling off: New thermometer site should lower the highs," The Sacramento Bee, September 12, 1998.6Id.