{"id":425529,"date":"2026-02-10T15:06:15","date_gmt":"2026-02-10T14:06:15","guid":{"rendered":"https:\/\/climatescience.press\/?p=425529"},"modified":"2026-02-10T15:06:17","modified_gmt":"2026-02-10T14:06:17","slug":"another-temperature-bias-the-shrinking-stevenson-screen-warming","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=425529","title":{"rendered":"Another Temperature Bias: The Shrinking Stevenson Screen = Warming"},"content":{"rendered":"\n
\"An<\/figure>\n\n\n\n

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From Watts Up With That?<\/a><\/p>\n\n\n\n

By Anthony Watts<\/a><\/p>\n\n\n\n

Many of you may recall that I got my start in climate skepticism back in 2006 when I started looking at the paint on\u00a0Stevenson Screens<\/a>\u00a0\u2013 because there was a change from the original lime-whitewash paint in the 1890s to modern latex paint.<\/em><\/p>\n\n\n\n

I figured there was a bias, and latex paint made the shelter warmer due its different IR signature.<\/em><\/p>\n\n\n\n

Temperature sensor tests over a month proved I was right. But in looking at temperature shelters in my area, I discovered an even bigger problem \u2013 most were sited near heat sources and heat sinks, in contradiction to NOAA\u2019s own published siting standards. <\/em><\/p>\n\n\n\n

This started my journey to uncover just how bad the temperature observing network actually was. Comprehensive reports I made\u00a0in 2009<\/a>\u00a0and\u00a0again in 2022<\/a>\u00a0showed that surface measurements were a huge warm biased mess.<\/em>\u00a0This paper is over 10 years old, but I somehow missed it. I\u2019m correcting that oversight.<\/em><\/p>\n\n\n\n

Now, to add to that mess, comes this revelation \u2013 the Australian Bureau of Meteorology changed the size of Stevenson Screens to something that had just ~ 25% of the volume of the original, and did not run parallel tests to see if the conversion mattered. \u2013 Anthony<\/em><\/p>\n\n\n\n

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Craig Kelly of the AFEE in Australia writes on X.com<\/a><\/p>\n\n\n\n

The peer-reviewed science confirms that shrinking the size of Stevenson Screens increased average temperatures across a year by 0.54\u00b0C and, on hot summer days, it can increase the maximum temperature by 1.7\u00b0C.\u00a0<\/p>\n\n\n\n

https:\/\/waclimate.net\/stevenson-sizes.pdf<\/a>\u00a0<\/p>\n\n\n\n

Yet the BOM denies the existence of this peer-reviewed science, pretends that it doesn\u2019t exist, and claims that shrinking the screens by 74% had no effect on the recorded temperatures.<\/p>\n\n\n\n

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The peer-reviewed science confirms that shrinking the size of Stevenson Screens increased average temperatures across a year by 0.54\u00b0C and, on hot summer days, it can increase the maximum temperature by 1.7\u00b0C.https:\/\/t.co\/TtOPMEa3Z7<\/a>

Yet the BOM denies the existence of this\u2026 https:\/\/t.co\/QDzdlZ4zc6<\/a> pic.twitter.com\/kjv2PtSWt0<\/a><\/p>— Craig Kelly:\ud83c\udde6\ud83c\uddfaFoundation for Economic Education (@craigkellyAFEE) February 6, 2026<\/a><\/blockquote>