Earlier this year, the National
Oceanic & Atmospheric Administration reported 2006 as ”the warmest
year on record" for the United States-- a statement the media trumpeted
from coast to coast. A few months later, the NOAA revised their figures,
saying it was actually the second warmest on record. Unsurprisingly, the
correction drew little attention.
But just how accurate are these figures? The NOAA generates them from a network of 1,221
simple weather stations, usually no more a thermometer inside a tiny wooden
hut, most operated by volunteers, not scientists. The network has been in
operation since 1900, and provides the official baseline data for both the NOAA
and global warming modelers. To ensure accurate data, the sites are
supposed to conform to several guidelines, such as minimum distance from other
buildings, hot pavement, etc.
California meteorologist Anthony Watts began surveying these sites recently, to
see just how well they're being maintained. His site, surfacestations.org,
has detailed a surprising number being operated in a manner guaranteed to
compromise their data. The problem is recent development, which has
placed many sites next to direct or indirect sources of heat.
In a prime example,
a site in Orland, CA (which meets good guidelines) has shown a pattern of
declining temperatures for many years. A few miles away, a station in
Marysville has shown a rising pattern...but the station is now next to
dark asphalt, and only a few feet from the exhaust vent of a commercial AC unit. Another site is near a large barrel used for
burning trash. One site even had a light bulb burning inside the tiny
enclosed hut, effectively warming the thermometer by several degrees.
Surfacestations.org has only surveyed 48 of the total sites, but problems
abound. Watts says this raises serious doubts about the accuracy of the
network, the only source of long-term historical data for US temperature data.
The NOAA did not return a request for comments on the accuracy of their
monitoring network.