When William Ruddiman stepped away from the classroom in 2001, he expected to be more retired by now. But eight years later, the UVA emeritus professor of environmental sciences just can’t seem to stop working, all because of a little idea of his that humans haven’t just been changing the planet’s climate over the last 200 years—but starting 7,000 years ago.
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UVA Professor Emeritus William Ruddiman has recently published a paper that argues that anthropogenic climate change began thousands of years earlier than the first coal plant or combustion engine. “I’m really certain that I’m right,” Ruddiman muses. “And I usually wouldn’t say that.”“My hypothesis is drawing a lot of attention,” says Ruddiman, who though retired, co-authored a paper published in August that further refines his notion that anthropogenic climate change happened thousands of years earlier than the first coal plant or combustion engine. “A good bit of [the attention] is favorable, and some of it is decidedly not favorable.”
Ruddiman isn’t the stereotypical kooky old professor trying to stir the pot. He’s decidedly not Pat Michaels, the retired UVA professor who regularly bashes global warming alarmists and doesn’t think climate change is so bad. Ruddiman holds mainstream scientific beliefs about climate change over the last 200 years, and thinks it’s “risky,” but avoids policy issues. As an author of one of the most popular textbooks on the earth’s climate, he treads lightly around the controversial political subject. “The last thing I want to do is write a book that misleads thousands of students with a biased case, so that’s given me reason to track the global warming issue very carefully,” he says.
Nevertheless, Ruddiman has become entangled in the fray by virtue of his recent work. Originally, he was simply trying to make sense of polar ice core samples, which provide a sort of historic record of the earth’s climate through the air bubbles they trap. Ruddiman couldn’t understand why methane levels went up several thousand years ago when the natural trend was down. Looking for reasons why, he stumbled on literature about what humans were up to starting 7,000 years ago—clearing forest, flooding rice paddies, and producing enough food to explode the populations of both people and domestic animals—and a lot more people and animals meant a lot more methane and carbon dioxide.
“They weren’t just putting a little methane and a little CO2 in the atmosphere, they were putting enough to reverse a natural downward trend in those gases,” says Ruddiman. “They had a huge effect. …Natural cycles don’t explain that.”
Ruddiman believes that those raised levels were enough to offset a cooling trend that would have made life nastier for humans at that time. That aspect of his work attracted the attention of the global warming skeptics, who have alternately cheered and disparaged Ruddiman’s work.
“The climate skeptics at first loved my theory, because the way they boiled it down was, ‘Greenhouse gases must be our friend because they saved us from oncoming glaciation. Greenhouse gases are good,’” says Ruddiman. “That’s the stupidest argument I can imagine.”
It was quickly pointed out that if humans 5,000 years ago had such a large impact on the global climate with relatively little methane and CO2, then imagine what an impact we’re currently making with all of our emissions. “They’re admitting that the climate system is as sensitive as mainstream scientists think it is. That’s exactly the last thing that the skeptics would want to do.”
The skeptics soon turned on him; Ruddiman recently collected a Top 10 list of insults.
“Number 2 was ‘Gore lemming,’” Ruddiman says with a chuckle. “The winner was ‘Fetid minded warminista.’ It’s helpful with this stuff to have a sense of humor and not take anything personally.”
It helps that he has the fortitude of conviction. “I’m really certain that I’m right,” Ruddiman muses. “And I usually wouldn’t say that.”
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