by R. Pielke Jr, June 16, 2022 in TheHonestBroker

It’s hot. Real hot. Heat waves in the United States surely must be the most visible and impactful sign of human caused climate change, right? Well, actually no. Let’s take a look at what the U.S. National Climate Assessment and the Intergovernmental Panel on Climate Change say about heat waves in the United States. What they say may surprise you.

Before proceeding, let me emphasize that human-caused climate change is real and significant. Aggressive policies focused on both adaptation and mitigation make very good sense. So too does being accurate about current scientific understandings. The importance of climate change does not mean that we can ignore scientific integrity — actually the opposite, it makes it all the more important. So let’s take a close look at recent assessment reports and what they say about U.S. heat waves.

The figure below comes out of the most recent U.S. National Climate Assessment(NCA). It shows the frequency (top) and intensity (bottom) of heat waves in the U.S. since 1900. The bottom figure is actually based on a paper that I co-authored in 1999, which serves as the basis for an official indicator of climate change used by the Environmental Protection Agency.

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