A recent Forbes column alleges that federal scientists are “doctoring” temperature data to fabricate a warming trend, after the National Oceanic and Atmospheric Administration announced that the last 12-month period was the warmest on record for the continental U.S.

But what the column paints as a nefarious conspiracy is actually just proper science -- NOAA painstakingly applies peer-reviewed adjustments to account for errors and gaps in the raw data from thousands of temperature stations across the country. The resulting temperature record has been independently evaluated and corroborated.

The column is by James Taylor of the Heartland Institute, the libertarian group that recently made headlines with a short-lived billboard campaign tastelessly invoking the Unabomber. This is not the first time Taylor has used his platform at Forbes to malign scientists and spread bad information about climate research.

At issue are the corrections NOAA uses to eliminate errors and known sources of bias from the raw weather station data (which Taylor likes to call “the real-world data”). Keep in mind that the U.S. represents just 2% of the Earth's surface so the data we're talking about are a small part of the evidence of global climate change.

The scientists (Taylor calls them “bureaucrats”) know that the raw data have flaws -- stations are moved, natural disasters knock stations offline, measuring instruments change -- so NOAA performs quality control using methods that are published in peer-reviewed papers. Taylor concedes that “it is, of course, possible that certain factors can influence the real-world temperature readings such that a correction in real-world temperature data may be justified.” But when he doesn't like the results, he concludes that the adjustments aren't valid corrections but “doctored data.”

Against NOAA's rigorous science, Taylor offers his “common sense,” which tells him that any corrections should, in fact, reduce warming:

Common sense indicates that if the real-world data need adjustment, the proper adjustment is to further reduce recent temperature readings. Yet the bureaucrats who oversee the data have instead doctored the data to show a false, long-term warming pattern.

How does Taylor, a lawyer, know what “the proper adjustment” is? He simply asserts that if there are factors biasing the data, “The most important such influence is the growth of towns and cities around temperature stations.” The urbanization would cause the raw data to show more warming than actually occurred and the adjustment should decrease that warming, according to Taylor. But a quick search on NOAA's website shows Taylor is wrong. The most important bias is not urbanization, as Taylor assumed, but a change in observation times. NOAA explains:

The most important bias in the U.S. temperature record occurred with the systematic change in observing times from the afternoon, when it is warm, to morning, when it is cooler. This shift has resulted in a well documented increasing cool bias over the last several decades and is addressed by applying a correction to the data.

It may not be common sense, but if common sense were good enough, we wouldn't need science.

NOAA's David Easterling also said via email that “Urban warming is a very small part of the overall warming, which also has been documented in the peer reviewed literature.” Easterling added, “The conclusions of the column sound like pure speculation on the part of the writer.”

Still suspect a giant conspiracy or massive incompetence at NOAA? Take it from physicist Richard Muller, who led an independent assessment of the surface temperature record last year. The study was partly funded by the Koch family, the oil tycoons who, incidentally, have also supported the Heartland Institute. Muller said via email that “it would be ridiculous” not to adjust the raw data. While noting that “some of the adjustments were made by humans using criteria that are somewhat subjective,” Muller said his own study produced “results that are very similar to those of the NOAA and NASA groups,” which indicates that the corrections are “done in an unbiased way.”

Muller's research also showed the effect of urban heat on the data “is minuscule because the urban heat islands are very small in area, and they contribute little to the overall land average.”

As outlined by a comprehensive report commissioned by the George W. Bush administration, climate change in the United States shows up in several other observations aside from the temperature data:

Climate-related changes are already observed in the United States and its coastal waters. These include increases in heavy downpours, rising temperature and sea level, rapidly retreating glaciers, thawing permafrost, lengthening growing seasons, lengthening ice-free seasons in the ocean and on lakes and rivers, earlier snowmelt, and alterations in river flows. These changes are projected to grow.

If we're in a “long-term cooling trend” as Taylor claims, he's got a lot to explain, and flimsy charges of “doctored data” aren't going to cut it.