Anthony Watts, proprietor of the website Watts Up With That has issued a press release announcing the result of a 5-year study of US temperature data for the period 1979-2008.
The major conclusions are:
Many factors, combined with station siting issues, have led to a spurious doubling of U.S. mean temperature trends in the 30 year data period covered by the study from 1979 – 2008.
Poorly sited station trends are adjusted sharply upward, and well sited stations are adjusted upward to match the already-adjusted poor stations.
Well sited rural stations show a warming nearly three times greater after NOAA adjustment is applied.
The raw data Tmean trend for well sited stations is 0.15°C per decade lower than adjusted Tmean trend for poorly sited stations.
Airport USHCN stations show a significant differences in trends from other USHCN stations, and due to equipment issues and other problems, may not be representative stations for monitoring climate.
What this means is that the U.S. temperature record is warm-biased and does not reflect the true temperature record.
Watts and co-authors Evan Jones of New York, Stephen McIntyre of Toronto, Canada, and Dr. John R. Christy from the Department of Atmospheric Science, University of Alabama, Huntsville, have submitted their findings for publication and have released a pre-publication draft for all to see. The paper is titled “An area and distance weighted analysis of the impacts of station exposure on the U.S. Historical Climatology Network temperatures and temperature trends.” Read the draft paper here and see the accompanying charts here.
Watts writes of the study:
A re-analysis of U.S. surface station temperatures has been performed using the recently WMO-approved Siting Classification System devised by METEO-France’s Michel Leroy. The new siting classification more accurately characterizes the quality of the location in terms of monitoring long-term spatially representative surface temperature trends. The new analysis demonstrates that reported 1979-2008 U.S. temperature trends are spuriously doubled, with 92% of that over-estimation resulting from erroneous NOAA adjustments of well-sited stations upward. The paper is the first to use the updated siting system which addresses USHCN siting issues and data adjustments.
I suspect that the timing of Watts’ announcement is to counter a new re-analysis by Richard Muller who founded the Berkeley Earth Surface Temperature (BEST) project. In Watts’ opinion that study contained many errors. Prof Judith Curry, a climatologist at the Georgia Institute of Technology, a consulting member of the BEST team, said that the method used to by BEST to attribute human emissions to the warming was “way over simplistic and not at all convincing in my opinion.”
The graph below shows some of Watts et al. results. The bars show temperature trend per decade by region. The blue bars are raw data from well-sited stations, i.e., those without circumstances that influence the temperature. The yellow bars of from less-well sited stations, i.e., those with urban encroachment or other factors that compromise true temperature. Notice that in every case, the yellow bar trends are higher than the raw data of well-sited stations, indicating a warming bias due to site conditions. The red bars are the NOAA “adjustments” to the data. The red bars go into the official record.
Let the games begin.