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Saturday, February 10, 2007

Global warming predates modern industry
College of Wooster speaker: Global warming predates modern industry
15 hours ago
Staff Writer
WOOSTER -- There's more to global warming than automobile emissions, factory smokestacks, aerosol cans and other industrial innovations of the last couple hundred years, according to William Ruddiman, professor emeritus of Environmental Sciences at the University of Virginia.
Ruddiman on Wednesday presented "Farmers First Altered Climate Thousands of Years Ago" to a full audience inside the Lean Lecture Room at The College of Wooster. He explained it was not the industrial, but rather early farming practices, that first altered the climate and essentially led to the concept of global warming.
"If you came to a scientist, any scientist in my field four or five years ago and (asked) when did humans start to interfere with climate, the answer would come back to it was about 1800 ... That was the conventional wisdom," he said.
But Ruddiman argued the process of change began much earlier, thousands of years earlier, with agricultural practices such as irrigation and deforestation. He reviewed with his audience diagrams of two greenhouse gasses linked to climate change, methane and carbon dioxide, and showed how gaps in their patterns correspond to periods of heavy irrigation and deforestation.
Ruddiman explained methane gas is created from swampy areas like wetlands, where water and vegetation are prevalent and methane gas bubbles out. He showed a trend of methane decreasing until about 5,000 years ago, when it instead turned and began climbing. The reason, according to Ruddiman, was the rise of irrigation, in which Chinese farmers began heavy irrigation of their rice paddies, creating human-made wetlands and thereby more methane.
"An irrigated rice paddy is a wetland," he said. "It's a human-made wetland, not a natural wetland."
As for carbon dioxide, he said some 8,000 years ago, the levels reversed from a downward direction and began climbing, which he attributed to heavy deforestation, based on the logic trees sequester and utilize carbon dioxide.
He addressed large deforestation efforts of the past several thousand years, including a survey during William the Conqueror's era that indicated 90 percent of England had been deforested.
He said deforestation continues today, in places like the Amazon, but emphasized the extreme nature of historical deforestation and the recent efforts of reforestation, which have improved modern forest conditions.
Part of his information is based on core samples of ice that date back almost a million years, he said, in which tiny pockets bubbles of dated air can be analyzed for their methane and carbon dioxide content.
His research focuses on cycles over the past 10,000 years and beyond, and anomalies of those cycles.
"If you have cycles, you have predictability, you have a reason for knowing what should be happening at any period of time," he said.
Ruddiman recognized the effect the industrial period (past 200 years) has had on climate change and said today farming probably affects the climate very little compared to industry, but still emphasized the early influence of agriculture in climate changes.
Had the climate not been altered, he figured we would be experiencing another glaciation (ice age).
"Basically, we're overdue for a glaciation," he said. "If nature had stayed in control we'd be in one right now."
He explained how periods of plagues and war also have shown changes in greenhouse gasses, corresponding to changes in human population. During a question-and-answer session, Ruddiman was asked whether society would have to "kill off half the world" to lower its greenhouse gas level, since the levels apparently decrease with population.
He admitted to being a cynic about the forecast of global warming, but did not endorse killing anyone and instead expressed optimism new technology could find a way to combat the greenhouse gasses, such as microbes that can eat carbon dioxide and omit something other than greenhouse gasses.
Another answer might be engineering an optimal climate for earth, he explained, by tuning earth's climate to an internationally acceptable level. While it may sound like science fiction, it's something he said already is "coming into our capability" and expects to be a major issue over the next decade.
"If we keep going the way that we're going, we're going to make climate roughly as much warmer 200 years from now as the last ice age was colder," he said. "It's as big a deal as the ice age in reverse, and that's absolutely mainstream science."
Asked about the future of climate change and what people can do, he explained it's serious, but said most probably won't change their ways.
"I think we're going to live with a big part of the warming ..." he said. "We just don't have the will to give up our comforts."
Ruddiman is the author of the award-winning book "Plows, Plagues, and Petroleum: How Humans took Control of Climate," which won the 2006 Phi Beta Kappa Award in Science. It's a book explaining human impact on climate, which several in the college's geology department have read.
Jessica Hark, a senior geology major, said there's much talk about whether global warming is something that even exists, but said after listening to Ruddiman, the argument for it is valid.
"Just listening to some of the work that he's done, you could definitely say, you could make the argument that yes, it's valid," she said.
She said the presentation was interesting and valuable, and said his book is very accessible to most readers.
"Anybody could understand it, even if you haven't really been studying geology or science," she said.
Greg Wiles, professor of geology at The College of Wooster and coordinator of Wednesday's presentation, said he also has read Ruddiman's book and said his point of human impact on climate is important.
"I think the main thing is that humans do impact the environment," Wiles said.
Ruddiman's presentation was part of a symposium called "Global Climate Change" and will continue Feb. 20 at 7 p.m. in McGaw Chapel with "Possibilities in Problems: The Good Side of Global Warming," presented by Richard Alley, Evan Pugh Professor of Geosciences at Pennsylvania State University. Admission is free and open to the public.

Reporter Chris Kick can be reached at (330) 287-1635 or e-mail

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