Here is an interesting discussion about how "scientists" arrive at the global average temperature. I have always suspected that the historical records are highly suspect. Back around 1900 and until recently communities had a thermometer situated in some convenient place, not necessarily an appropriate place, and sometime every afternoon some guy named 'Old Stumpy' went out and recorded the "official high" for the day. Sometimes around 6 AM he recorded the "minimum." This was not done with any scientific rigor.

Recently I have been reading that 2006 was the hottest year on record for the US. It turns out that was not true. In addition, not mentioned in the article below, worldwide 2006 was about 0.15 F cooler than 2005. I don't read much about that either. Of course, the true believer scientists don't worry about that. They are certain that carbon dioxide is causing the global average temperature to go up, so they fall back on the error bound of the measurements which is about 0.5 F. (I would argue that the historical record has a much larger error margin.)

Here is the article:

By Bill Steigerwald
TRIBUNE-REVIEW
Sunday, June 17, 2007

Remember in January when the National Oceanic & Atmospheric Administration (NOAA) and its good friends in media trumpeted that 2006 was the warmest year on record for the contiguous United States?

NOAA based that finding - which allegedly capped a nine-year warming streak "unprecedented in the historical record" - on the daily temperature data that its National Climatic Data Center gathers from about 1,221 mostly rural weather observation stations around the country.

Few people have ever seen or even heard of these small, simple-but-reliable weather stations, which quietly make up what NOAA calls its United States Historical Climatology Network (USHCN).

But the stations play an important role in detecting and analyzing regional climate change. More ominously, they provide the official baseline historical temperature data that politically motivated global-warming alarmists like James Hansen of NASA plug into their computer climate models to predict various apocalypses

NOAA says it uses these 1,221 weather stations -- which like the ones in Uniontown and New Castle are overseen by local National Weather Service offices and usually tended to by volunteers -- because they have been providing reliable temperature data since at least 1900.

But Anthony Watts of Chico, Calif., suspects NOAA temperature readings are not all they're cracked up to be. As the former TV meteorologist explains on his sophisticated, newly hatched Web site surfacestations.org, he has set out to do what big-time armchair-climate modelers like Hansen and no one else has ever done - physically quality-check each weather station to see if it's being operated properly.

To assure accuracy, stations (essentially older thermometers in little four-legged wooden sheds or digital thermometers mounted on poles) should be 100 feet from buildings, not placed on hot concrete, etc. But as photos on Watts' site show, the station in Forest Grove, Ore., stands 10 feet from an air-conditioning exhaust vent. In Roseburg, Ore., it's on a rooftop near an AC unit. In Tahoe, Calif., it's next to a drum where trash is burned.

Watts, who says he's a man of facts and science, isn't jumping to any rash conclusions based on the 40-some weather stations his volunteers have checked so far. But he said Tuesday that what he's finding raises doubts about NOAA's past and current temperature reports.

"I believe we will be able to demonstrate that some of the global warming increase is not from CO2 but from localized changes in the temperature-measurement environment."

Meanwhile, you probably missed the latest about 2006. As NOAA reported on May 1 - with minimum mainstream-media fanfare - 2006 actually was the second- warmest year ever recorded in America, not the first. At an annual average of 54.9 degrees F, it was a whopping 0.08 degrees cooler than 1998, still the hottest year.

NOAA explained that it had updated its 2006 report "to reflect revised statistics" and "better address uncertainties in the instrumental record." This tinkering is standard procedure. NOAA always scientifically tweaks temperature readings for various reasons -- weather stations are moved to different locations, modernized, affected by increased urbanization, etc.
NOAA didn't say whether it had adjusted for uncertainties caused by nearby burn barrels.