Climate scientist Dr. Michael Mann won a defamation lawsuit against two conservative writers last week.

The verdict was 12 years in the making. In 2012 writers Rand Simberg and Mark Steyn accused Mann of manipulating his data related to his famous 1998 “hockey stick” graph, which depicts rising global temperatures after the industrial revolution. Simberg compared him to former Penn State football coach and convicted child sex abuser Jerry Sandusky in a blog post for a libertarian think tank. Steyn later referenced Simberg’s article in a National Review piece, calling Mann’s work “fraudulent.”

Reviews by Penn State (Mann’s home institution at the time) and the National Science Foundation, found no scientific wrongdoing. And in fact the iconic graph has since been supported by numerous studies.

What does this ruling signal about the public’s understanding of climate change research? And the limitations of free speech?

Ira talks with Dr. Michael Mann, professor of Earth & environmental science at the University of Pennsylvania and author of Our Fragile Moment: How Lessons from Earth’s Past Can Help Us Survive the Climate Crisis.

Transcripts for each segment will be available after the show airs on sciencefriday.com.

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