Tuesday, May 22, 2007

What makes our current climate extraordinary?

Nothing in particular, says Dr. Reid Bryson, a highly respected climatologist in Wisconsin. Here is an extended quote from the article referenced by Boortz in the previous post:

Bryson is a believer in climate change, in that he’s as quick as anyone to acknowledge that Earth’s climate has done nothing but change throughout the planet’s existence. In fact, he took that knowledge a big step further, earlier than probably anyone else. Almost 40 years ago, Bryson stood before the American Association for the Advancement of Science and presented a paper saying human activity could alter climate.

“I was laughed off the platform for saying that,” he told Wisconsin Energy Cooperative News.

In the 1960s, Bryson’s idea was widely considered a radical proposition. But nowadays things have turned almost in the opposite direction: Hardly a day passes without some authority figure claiming that whatever the climate happens to be doing, human activity must be part of the explanation. And once again, Bryson is challenging the conventional wisdom.

“Climate’s always been changing and it’s been changing rapidly at various times, and so something was making it change in the past,” he told us in an interview this past winter. “Before there were enough people to make any difference at all, two million years ago, nobody was changing the climate, yet the climate was changing, okay?”

“All this argument is the temperature going up or not, it’s absurd,” Bryson continues. “Of course it’s going up. It has gone up since the early 1800s, before the Industrial Revolution, because we’re coming out of the Little Ice Age, not because we’re putting more carbon dioxide into the air.”

Little Ice Age? That’s what chased the Vikings out of Greenland after they’d farmed there for a few hundred years during the Mediaeval Warm Period, an earlier run of a few centuries when the planet was very likely warmer than it is now, without any help from industrial activity in making it that way. What’s called “proxy evidence”—assorted clues extrapolated from marine sediment cores, pollen specimens, and tree-ring data—helps reconstruct the climate in those times before instrumental temperature records existed.

We ask about that evidence, but Bryson says it’s second-tier stuff. “Don’t talk about proxies,” he says. “We have written evidence, eyeball evidence. When Eric the Red went to Greenland, how did he get there? It’s all written down.”

Bryson describes the navigational instructions provided for Norse mariners making their way from Europe to their settlements in Greenland. The place was named for a reason: The Norse farmed there from the 10th century to the 13th, a somewhat longer period than the United States has existed. But around 1200 the mariners’ instructions changed in a big way. Ice became a major navigational reference. Today, old Viking farmsteads are covered by glaciers.

Bryson mentions the retreat of Alpine glaciers, common grist for current headlines. “What do they find when the ice sheets retreat, in the Alps?”

We recall the two-year-old report saying a mature forest and agricultural water-management structures had been discovered emerging from the ice, seeing sunlight for the first time in thousands of years. Bryson interrupts excitedly.

“A silver mine! The guys had stacked up their tools because they were going to be back the next spring to mine more silver, only the snow never went,” he says. “There used to be less ice than now. It’s just getting back to normal.”