When greenhouse gas meets ice age
Sep 18, 2009 10:54 AM, By Elton Robinson, Farm Press Editorial Staff
Could global warming one day create beachfront property in Clarksdale, Miss.? Or cotton production in Ames, Iowa? Or is it just as likely, as some scientists believe, that in the future a large glacier will occupy much of North America — 2 miles thick in some places?
In geologic time, glacial periods dominate warming periods, lasting up to 10 times longer. Scientists say the current warming trend began about 11,000 years ago. No one can deny that during this time, humankind has flourished, and agriculture’s development has been nothing short of phenomenal.
However, since 10,000 years is about the average duration of a warming trend, scientists believe the planet is now past-due for another ice age. And this begs a very important question about man-made global warming. What happens (drum roll, please) when greenhouse gas meets ice age?
Let’s start with James A. Hansen, director of NASA’s Goddard Institute for Space Studies. In an article just last week in the New York Times, he says man is now firmly in the planet’s driver’s seat. “We have taken over control of the mechanisms that determine the climate change.”
Okay, but can we take on Big Ice?
Yes, says Lorraine Lisiecki, of the University of California, Santa Barbara, in an interview with National Geographic News. She implies that man is now more powerful than the geological and cosmological forces that have reigned since time began. “Current greenhouse gas concentrations are probably similar to those that occurred three million years ago and are high enough to prevent an ice age for hundreds of thousands of years.”
Well, based on that analysis, I’d have to give Round One to global warming.
Other scientists firmly believe that no matter how much carbon dioxide we pump into the atmosphere today, an ice age is still going to happen. They believe small wobbles in the earth’s orbit have much more of an impact on the earth’s climatic cycles than piddly men.
“Orbital changes are in a slow dance leading to a peak (in glacial ice) 80,000 years from now,” said Eric J. Barron, director of the National Center for Atmospheric Research. “I can hardly imagine that human influences won’t have run their course by that time.”
Round Two — the ice age. It cometh.
The point of all this is that scientists have proven that there is a link between carbon dioxide and the earth’s surface temperatures, although that relationship may not as linear as once thought. But do we really understand how geologic forces impact the climate? Have we studied how proposed solutions for controlling carbon dioxide emissions stand up in geologic time? And I wonder. Is staving off another ice age — if it’s possible — such a bad idea? I say, let’s don’t take another step until we have a better idea of where we’re going, and at least try to answer these questions.
e-mail: erobinson@farmpress.com
