Can historical temperature data records be trusted? Haven't they been skewed by non-climate factors like instrument changes and "urban heat islands"?

October 29, 2020

Yes, we can trust NOAA's Global Historical Climatology Network (GHCN) data for three key reasons:

  1. NOAA uses quality control measures to ensure the temperature data are of the highest quality and accuracy for research purposes. NOAA is open and transparent about its quality control measures and anyone can read all about them in the published literature or on the NOAA website. Learn more.
  2. Both the temperature data record and NOAA’s analyses of the temperature data have been peer-reviewed by other, independent teams of scientists in the U.S. and internationally. No reasons have been found to question the integrity or the quality of the GHCN dataset. Learn more here and here and here.
  3. Perhaps most compelling reason: Mother Nature herself offers many lines of corroborating evidence that our world is warming—from melting ice sheets and glaciers, to the rising global sea level, to the earlier arrival of spring and longer warm seasons, to plant and animal species migrations. It is easy to conclude our world is warming even without the GHCN data. Learn more.

Okpilak Glacier

The marked retreat of Okpilak Glacier in Brooks Range, Alaska, is one example of glacier retreat worldwide. Images from the National Snow and Ice Data Center (NSIDC) Glacier Photograph Collection.


NOAA National Centers for Environmental Information, State of the Climate: Global Climate Report for Annual 2019, published online January 2020, retrieved on June 18, 2020, from

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