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Apply Official WMO Methods, Warming Shrinks Massively

If new techniques endorsed by the World Meteorological Organisation are applied to official figures, over half of the global warming reported by US land-based thermometers between 1979 and 2008 simply disappears, researchers have found.

The new study used the same raw temperature measurements as US government federal scientific agencies, but the team deployed a revised metric that was better at taking into account the quality of the weather stations that housed the thermometers.

Previous studies have used a cruder metric to gauge station quality, which has to be taken into account so as to allow for the effect of asphalt, urban development and other local factors on the readings at any given thermometer. The new station-quality metric improves on older methods, not merely relying on distance but also the density of heat sinks and sources near the thermometers.

When the more sophisticated classification system is used, some dramatic results are seen. The new study reveals that the US National Oceanic and Atmospheric Administration (NOAA) discarded the temperature trend from the higher quality weather stations in favour of a warming temperature trend from low quality weather stations.

But the most extraordinary aspect is that this improved metric for categorising weather station quality has been endorsed by the World Meteorological Organization since 2010. It was proposed by Michel Leroy of Météo-France, the French state weather service, who devised its cruder predecessor in 1999.

Yet it has been left to a group largely outside the climate establishment to first do the field work and then the maths, and apply the new metric to the data. The official agencies and climate academics have been able (some would say, required) to use the latest WMO-endorsed categorisation method for 18 months, but have failed to do so.

Enter Watts et al

The new paper is co-authored by TV weatherman and blogger Anthony Watts, the Climate Audit blog’s Evan Jones and Stephen McIntyre, and Dr John Christy from the Department of Atmospheric Science at the University of Alabama, Huntsville. Only Christy, who maintains the US satellite temperature monitoring network, can be considered part of the scientific climatology establishment.

The paper, titled An area and distance weighted analysis of the impacts of station exposure on the US Historical Climatology Network is detailed on Watts’ blog here. The paper [PDF] relied on physical field work by hundreds of volunteers, who created a sample of US weather stations using the new WMO classification system.

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