Just thermometers, indicating since the 1880 that the Earth is warming due to climate change.
Source: Dr. Richard Somerville. Video interview on ABC news.
The reporter asked him, "Are there questions about the data with the thousands of thermometers showing the Earth is warming?"
Dr. Somerville: "There are no Democratic or Republican Thermometers. Thermometers are thermometers. The world has been analyzing to death. People know how to read thermometers, treat the data, how to massage the numbers, check for errors, etc. They have done that in several different countries, and it shows that the world is unambiguously warming.
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