Heavily adjusted temperature dataset shows a warming trend, but can we trust it?

gavinNASA climatologist Gavin Schmidt, who has come under fire for being more activist than scientist, sent out a tweet yesterday predicting that 2016 would be the hottest year on record and said he was 99 percent sure of that claim. According to land-and-sea-based temperature stations, July 2016 was 0.1 degrees Celsius warmer than the 1950 to 1980 timeframe. But when compared to the 1930s, July still is not a record breaker. But only if you don’t rely on an adjusted temperature dataset.

Schmidt, a director for the National Aeronautics and Space Administration Goddard Institute for Space Studies (NASA GISS), is disseminating a chart on Twitter from a dataset that has been heavily adjusted to show a much larger warming trend than is actually occurring.

The adjustment bureau

The adjustments have also come under heavy criticism because it uses a temperature dataset that wiped away the strong 1998 El Niño:

Most of the world’s top meteorological organizations rely on the National Oceanic and Atmospheric Administration (NOAA) and NASA for data prior to 1982. According to Tony Heller at Real Climate #Science, the 1930s will still go down as the hottest decade in U.S. history, long before carbon dioxide (CO2) levels started to rise. Temperatures across the country were over 100 degrees F across the country the week of July 25, 1936. And July 9, 1936, is still one of the hottest days in U.S. history.

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