Thomas R. Karl

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Thomas R. Karl (born November 22, 1951, in Evergreen Park, Illinois) is a former director of NOAA’s National Centers for Environmental Information (NCEI). He joined the National Climate Centre in 1980, which later became the National Climatic Data Center. He worked there as a researcher, then Lab Chief, Senior Scientist, and eventually Director. When the center merged with others to form NCEI in 2015, he became its first director. He retired on August 4, 2016.

Karl led a study about whether there was a pause in global warming, a topic raised by the IPCC Fifth Assessment Report. The study, published in Science in June 2015, used existing data and newer corrections for biases in ocean and land temperature measurements. It found no real slowdown, even for 1998–2012—the period often cited. The study used updated ocean data (Extended Reconstructed Sea Surface Temperature v4) and land data (International Surface Temperature Initiative integrated with NOAA’s Global Historical Climatology Network). Some scientists welcomed the results, though others noted the short-term warming rate could be slower than in some other comparable periods.

After the results were published, Karl faced criticism from climate change denialists, including Lamar Smith, then chair of the House Science Committee. In 2017, another group of scientists using different methods confirmed Karl’s findings.