Independent Audit Supports Official
U.S. Surface Temperature Record

By Zeke Hausfather

Measuring the temperature of an entire country is no easy undertaking.

Numerous factors such as the heat island effect of urban areas and poor quality measuring sites mean that any aggregate temperature calculation must adjust for potential biases.

A recent effort by Anthony Watts and a team of dozens of volunteers at SurfaceStations.org succeeded in surveying and photographing more than one third of the 1,221 temperature measuring stations in the US Historical Climatology Network (USHCN). An analysis of the temperature trend in the stations identified as well sited and rural corresponds surprisingly well with the official NASA GISTEMP temperature record of the United States. The similar findings suggest that, despite a number of poor quality measuring stations, the official temperature record for the U.S. appears to be quite accurate.

The SurfaceStations effort was born out of the Climate Audit community managed by Steve McIntyre, a former mining executive and economist. McIntyre's site provides an outlet for those interested in challenging methodologies underlying various aspects of climate science. His work has been largely responsible for the widely reported controversy surrounding the "hockey stick", and also for the recent and widely publicized NASA revision of the continental U.S. temperature record.

SurfaceStations began as a project by Anthony Watts, a meteorologist and TV weatherman for more than a decade. He and a team of volunteers have been scouring the country to photograph and categorize all of the sites in the USHCN temperature monitoring network.

Each of those sites is rated on a scale of one through five based on site quality and conformity with siting rules, with one being the best site type and five the worst. Sites are further divided into urban and rural sites.

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Surface stations surveyed as of October 10th, 2007. Figure from SurfaceStations.org.

The figure to the right shows the 421 sites surveyed as of October 10, 2007, as red dots and the remaining 800 unsurveyed sites as blue dots. Watts and his volunteers approached the project deeply skeptical of the official temperature record, with Watts stating that the results will likely "demonstrate that some of the global warming increase is not from CO2 but from localized changes in the temperature-measurement environment."

Watts's efforts have generated considerable media coverage, with many reporting on his effort as a serious challenge to the conventional wisdom that the United States has experienced significant anthropogenic warming over the last century.

After Watts and his team released the data from the sites surveyed so far, John Vliet, a Canadian software developer and mathematician, decided to compare to the official NASA GISTEMP record the temperature record from the sites identified as both good quality (rated one, two, or three) and rural. The results were surprising to many in the Climate Audit community, as they found that the GISTEMP record matches the best site rural record quite well.

"For the USA lower 48, there is excellent agreement between GISTEMP and my results using only the best stations," Vliet explained. Vliet has published the code he used in an open source project called OpenTemp.org, and his calculations have so far stood up to the rigorous analysis of the community at Climate Audit.

As Gavin Schmidt from NASA Goddard explained, "That fact that his analysis is very similar to GISTEMP is a validation of both approaches." The comparison between the good rural station record (CRN123R) and the official U.S. record (GISTEMP) are shown in the figure below, with the difference between the two records shown as blue bars.

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Continental U.S. temperature record comparison. Figure from John Vliet and OpenTemp.org.

So what is the lesson for journalists in this somewhat esoteric discussion?

Sites like Climate Audit can do valuable work to poke holes and challenge the somewhat insular world of climate scientists. However, the media should be aware of the risks in mistaking these holes for actual cracks in the underlying science of anthropogenic climate change. Imprecise reporting in these cases can lead to a reporter’s blowing things completely out of proportion.

Independent efforts such as these certainly bear watching, but responsible reporters may best serve their audiences' interests by awaiting results in the published peer-reviewed literature before declaring that they pose substantive challenges to the broadly scientific view of climate change.

In this case, at least, it appears that the official temperature record did a good job in correcting for factors like urban heating and bad site characteristics. A challenge facing the Climate Audit community now is to review the temperature record from around the globe, as many places lack the rigorous standards that U.S. surface stations are supposed to meet.

AUTHOR

Zeke Hausfather is a regular contributor to the Yale Forum (zeke@yaleclimatemediaforum.org).