This is really old news, but sauce for the goose ...
Science relies on data collection. Technology moves on year by year. As new technologies and methodologies become available scientists fall over themselves to update and correct their data.
Sometimes the new data needed for data correction comes from unexpected sources.
Anthony Watts, founder of wattsupwiththat.com set up surfacestations.org to collect data on US weather stations with the objective of showing up errors which would support his view that anthropogenic global warming isn't happening.
The idea was to show how many of these stations are in locations where the readings might be expected to be skewed by adjacent sources of warm air.
Watts' data was examined in On the reliability of the U.S. Surface Temperature Record, Aug 27 2009, revised Dec 21 2009, published in the Journal of Geophysical Research. The trends from poorly sited weather stations were compared to well-sited stations and showed a bias associated with poorly sited stations. A net cooling bias.
The authors of the report were very grateful to Anthony Watts:
Acknowledgements: The authors wish to thank Anthony Watts and the many volunteers at surfacestations.org for their considerable efforts in documenting the current site characteristics of USHCN stations. ...The irony of it!
Anthony Watts has a net-wide reputation as a denier of global climate change:
Watts publishes stuff by deniers like Roger Pielke, Sr. that is so lame, so willfully anti-scientific in its effort to confuse short-term weather with long-term climate trends, that it actually tries to dismiss the startling 30-year record of Arctic sea ice loss with the statement that “since 2008, the anomalies have actually decreased”http://climateprogress.org/.../the-video-that-anthony-watts-does-...