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Please note!
This fact brief was originally published as an experiment to test the concepts behind fact briefs.
Readers should be aware that while there is still a lot of useful information in fact briefs like this one, not all of them reflect Gigafact's current methods and standards for fact briefs. If you come across any that you feel are out of date, don't hesitate to contact us at support@gigafact.org.
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FACT BRIEF

Do record US heat waves in the 1930s disprove global warming?

By Claire Zimmerman
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NO

The most severe heat waves in the U.S. did occur in the 1930s, but overall temperatures today are higher than they were then, both domestically and globally.

Climate is a measure of weather overtime. Global average temperatures have trended upward since the industrial revolution. There is a scientific consensus that human activities which emit heat-trapping gases into the atmosphere are the primary cause. Globally, July 2023 was the hottest month on record.

During the Dust Bowl, drought, combined with poor land use practices, eroded the soil, depriving it of its temperature-moderating moisture. Land heats up more quickly than water, which enabled already hot temperatures to soar even higher.

The EPA’s U.S. Annual Heat Wave Index is a combined measure of how many times there was a period of four or more days of unusually high temperatures in a given percentage of the country.

This brief has been updated to reflect the most up-to-date information as of July 31, 2023.

This fact brief is responsive to conversations such as this one.
Sources
US Environmental Protection Agency Climate Change Indicators: Heat Waves (Figure 3)
National Oceanic and Atmospheric Administration Climate Change: Global Temperature
Environmental Research Letters Consensus on consensus: a synthesis of consensus estimates on human-caused global warming
World Meteorological Association July 2023 is set to be the hottest month on record
National Weather Service Heat wave of July 1936
National Oceanic and Atmospheric Administration Radiative Heating of Land and Water
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Gigafact
Between 2020 and 2022, under close editorial supervision, Gigafact contracted a group of freelance writers and editors to test the concepts for fact briefs and provide inputs to our software development process. We call this effort Gigafact Foundry. Over the course of these two years, Gigafact Foundry writers published over 1500 fact briefs in response to claims they found online. Their important work forms the basis of Gigafact formats and editorial guidelines, and is available to the public on Gigafact.org. Readers should be aware that while there is still a lot of relevant information to be found, not all fact briefs produced by Gigafact Foundry reflect Gigafact's current methods and standards for fact briefs. If you come across any that you feel are out of date and need to be looked at with fresh eyes, don't hesitate to contact us at support@gigafact.org.
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About fact briefs published on Gigafact
Fact briefs are short, credibly sourced summaries that offer “yes/no” answers in response to claims found online. They rely on publicly available, often primary source data and documents. Fact briefs are created by contributors to Gigafact —a nonprofit project looking to expand participation in fact-checking and protect the democratic process. See all fact briefs here.