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Showing posts with the label bias correction

Correcting for Time of Observation Bias

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You'll frequently see contrarian influencers on social media showing the differences between "raw" and "adjusted" temperatures for the United States that indicate that CONUS warming in the "adjusted" temperatures is greater than in the "raw" data. We're often told this indicates that scientists have adjusted CONUS temperatures to make them cooler in the past, thus making the amount of warming that has occurred in the US larger in the "adjusted" temperature data than in the "raw" data. It's then frequently just assumed that this is because "liberal" scientists need are conspiring with nefarious intent to tamper with and manipulate temperature data to create artificial warming trends in US temperatures. In another post I share some dishonest way in which contrarians exaggerate the difference between the "raw" and adjusted temperatures, but even in properly plotted comparisons, the final "adju...

Sniff Test Regarding Urbanization Biases

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In another post , I covered some of the many reasons why scientists have concluded that urbanization biases are not responsible for any significant fraction of global warming. In order to avoid too much duplication with that post, I'll only briefly summarize the reasons: Homogenization Corrects Urbanization Bias. While cities are warmer than rural areas, they warm at about the same rate as rural areas. The bias is caused by urbanization. That is, as rural areas become more urban, they will warm at a faster rate than rural and urban areas. This bias is effectively removed by homogenization. Very Rural Stations Warm at Least as Rapidly as All Stations. Wickham et al 2013 compared the most rural land stations globally and compared them to all land stations. The study found that "very rural" stations were warming at least as rapidly as all stations. If urbanization biases were making a significant contribution to global warming, then the most rural stations would warm more sl...

Data Tampering by Shewchuk and Heller

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If you follow climate discussions on X, you're bound to see John Shewchuk and/or Tony Heller show graphs that reportedly show that NOAA is tampering with temperature data to fabricate global warming with spurious warming trends. I've gone over many of the reasons why this is nonsense before in posts about bias correction and so-called  ghost stations . I think it's good to show what's actually going on with the graphs they present as "proof" of data manipulation, though. I think it can be easily demonstrated here that it's actually Shewchuk and Heller that are tampering with data. Shewchuk (Top) and Correct (Below) Above are two graphs. The top graph shows what John Shewchuk claims shows that NOAA is manipulating data. It shows USHCN "raw" and "altered" Tmax data for 1900 to 2023. The bottom graph above is the correct plot of NOAA's published data from the current and correct dataset (nClimDiv) with a 5-year running mean to match S...