Back in 2007, climate ground station researcher, Anthony Watts came to the attention of the world’s climate scientists afer he surveyed over 75% of the 1200-plus U.S weather stations and found many to be inaccurate by more than 2°C, largely due to being located within 10 meters of an artificial heating source. But another little-reported fact that Watts uncovered was that modern paints now applied to the temperature measuring boxes (called Stevenson screens) are also seriously contaminating the measurements of global ground temperature stations.
Watts said, “You don’t read anything about this on repainting of weather shelters worldwide because there’s no maintenance record to correlate the painting, its been done ‘ad hoc’ by local operators of the stations.”
Watts had discovered that the modern paints absorb far higher levels of solar radiation than the old-fashioned whitewash traditionally used on these stations. The newer paints cause greater absorption of heat unlike the old-fashioned whitewashed variety, thus increasingly contaminating the temperature data.
So what is the temperature contamination effect of paint work? Well, paints that appear “white” and reflective in visible light have different properties in infrared. Some paints can even appear nearly “black” and absorb a LOT of infrared, and thus biases the thermometer readings. This is something easily overlooked by the casual observer because it isn’t only the energy from the sun we see in the visible spectrum that creates a heating effect on Earth, the invisible part of the light spectrum also plays a major role in warming our planet.
This is how Anthony Watts explained the issue:
“In a nutshell, nobody seems to have experimentally investigated this issue. It seems that weather station shelters known as Stevenson Screens (the white chicken coop like boxes on stilts, housing thermometers outdoors) were originally painted with whitewash, which is a lime-based paint, and reflective of infra-red radiation but its no longer available, and newer paints have been used that much [sic] different IR characteristics.”
According to Wikipedia, a Stevenson screen or instrument shelter is an enclosure to shield meteorological instruments against precipitation and direct heat radiation from outside sources, while still allowing air to circulate freely around them. It forms part of a standard weather station. The Stevenson screen holds instruments that may include thermometers (ordinary, maximum/minimum), a hygrometer, a psychrometer, a dewcell, a barometer and a thermograph. Stevenson screens may also be known as a cotton region shelter, an instrument shelter, a thermometer shelter, a thermoscreen or a thermometer screen. Its purpose is to provide a standardised environment in which to measure temperature, humidity, dewpoint and atmospheric pressure.
The standardised global weather station was perfected and commissioned in the 1890’s and the originally specification was that they be painted with whitewash. However, since the mid 1970’s whitewash was no longer freely available as modern, more versatile paints replaced traditional and less convenient longer-drying types. Like most of the major international exterior paint manufacturers, Merck, has a host of proprietary pigment families such as Iriodin®, Xirallic®, Miraval®, Colorstream®, Pyrisma® as well as Biflair®, Minatec® and Solarflair.
Merck has been manufacturing these new paints transparent to IR since the 1960’s because of their superior weather resistant properties. But an issue not uppermost in the minds of paint manufacturers was that modern synthetic paints, which dry far quicker on application, do so largely because they absorb so much extra invisible IR energy – unlike slow-drying whitewash which is very good at reflecting heat-inducing near-infrared radiation.
It seems that by pursuing the important customer-driven need for faster drying paints companies such as Merck are adding the infrared-absorbing pigment Minatec® which speeds up the drying process of the paint coating – a boon for practical purposes but giving an unintended consequence to climatologists’ ground temperature readings. As Merck states in its sales literature, the newer paint products are “geared specifically towards the goal of increased production capacities along with reduced energy costs.”
The Arizona State University department of Physics and Astronomy has reported on the problem of paint pigments and their reaction to infrared:
“Almost all the paint pigments have the same properties as Si and Gallium Arsenide. They are transparent to infrared light. This transparency to IR occurs because the paint pigments are nearly all oxides (such as titanium white, titanium oxide) or sulfides (such as the red vermilion, mercury sulfide). In pure form, they are insulators or semiconductors with almost no electrons available for light absorption in the IR.“
Anthony Watts explained in greater detail how this is bad for the Stevenson temperature stations:
“This means that the infrared radiated from the sun, ground, and nearby objects goes straight to the wood, heating it, and likely biases the thermometer inside the shelter.“
Watts maintains that the steady switch in paints has gravely distorted modern temperature records because it is not officially monitored by any of the main agencies entrusted with collecting the climate data. Mr. Watts first raised his concerns among scientists in 2007 but since then climatologists who have been aware of this problem have done nothing to account for this anomaly. It seems they would rather just shrug their shoulders and use the data anyway.
Coupled with other documented biases, skeptics of the man-made global warming theory may have stumbled on to a very important point at a time when it’s becoming clearer that the data collection methods used to get surface temperatures may be riddled with biases and errors.
Thanks to the research of analysts such as Anthony Watts it seems that the world, in the midst of the worst winter in 30 years, has been given further good cause to doubt climatologists’ findings, knowing there is the distinct possibility that significant measurement bias has crept in with this paint issue.
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