To study global climate change, Kirk Johnson has looked at lots of plants, living and long dead.

He has been to the Amazon Basin 15 times, collecting leaves in a drenching-wet world where a stand of 500 trees might contain 300 distinct tree species.

He has been also to Ellesmere Island, 1,000 miles north of Barrow, Alaska, where there is exactly one species of woody plant, the Arctic willow. It grows three inches high, sprouts tiny leaves in late June and drops them to the ground - maybe an inch - in late July.

But Ellesmere Island was once a very different place. Scientists have drilled into the floor of the Arctic Sea near Ellesmere, bringing up samples of fossil azolas, which are virtually identical to floating ferns that blanket vast lakes in the Amazon Basin. Other researchers have found the fossil remains of crocodiles, snakes and turtles on Ellesmere, dating from roughly 48 million years ago.

During a speech in Billings Wednesday, Johnson also talked about finding huge fossil palm fronds near Kemmerer, Wyo., and 165 species of fossil leaves, many of them similar to those found in the Amazon, from a dig near Denver.

'See it to believe it'

It's no secret that the world has undergone dramatic shifts in climate, Johnson said, but there is nothing like collecting and analyzing the fossils yourself.

"You've got to see it to believe it," he said.

That was also his message in regard to contemporary, human-caused climate change, and he delivered his conclusions to an audience that some might regard as unreceptive. He spoke over the lunch hour Wednesday to a meeting of the Montana Geological Society in the Petroleum Club at the Crowne Plaza Hotel.

Billings was Johnson's seventh stop on a nine-city Distinguished Lecture Series sponsored by the American Association of Petroleum Geologists. Johnson, vice president of research and collection and chief curator at the Denver Museum of Nature and Science, said he has endured some tough questioning at other stops, but the 20 people at the Petroleum Club responded warmly to his spirited tour of ancient climates.

That may be because much of his speech was devoted to his exotic adventures and oddities encountered along the way. He talked of fishing in the Amazon Basin with its 3,500 species of fish, including armored catfish, giant prehistoric-looking creatures and pink freshwater dolphins.

"When you get a strike, you really don't know what's going to come out of that water," he said.

He also spoke wistfully about finding fossils, early in his career, at excavations on the site of what would become the Denver International Airport. At one point he found an 11-foot fossil palm frond, he said, but it was embedded in such a heavy hunk of rock that he couldn't remove it. It is still there, under one of the runways, he said.

Carbon dioxide levels

Easing his way into current climate change, Johnson said two of the most compelling things he's seen were a chart of carbon dioxide levels in the atmosphere between 1957 and 2005, and space photographs of Arctic Sea ice.

The CO2 measurements, made at Mauna Loa, Hawaii, showed levels of that gas increasing from 310 parts per million in 1957 to 380 ppm in 2005. Johnson earned his doctorate in geology and paleobotany from Yale University and said he is used to thinking in terms of very long periods of time.

When you see dramatic changes like the rise in CO2 levels occur on a human time scale - he was born in 1961, shortly after the measurements began - "you take notice," he said.

The photos of Arctic Sea ice, Johnson said, show the annual area of shrinkage, or how much of the sea is covered with ice in September, the warmest time of year. Since 1980, the extent of coverage has shrunk dramatically, and some scientists are predicting that the North Pole itself will be ice-free in September five years from now. Others say it won't happen for 30 or 40 years, but they all say it will happen.

Johnson said his research points to the importance of doing climate research in the polar regions. His brief history of planetary climate change showed that the earth has been through many more "greenhouse" periods than "icehouse" periods. But it has always been the case that during warm periods, temperatures rise much more dramatically in the north and south than they do in equatorial regions.

If you want to know about climate change, he said, "go to Barrow, Alaska, and ask the Eskimos what's going on."

Finding a solution

Toward the end of his talk and during a question-and-answer session, Johnson said he didn't pretend to know how to stop global warming. The important thing is to study the issue without politicizing it or playing on people's fears, he said.

That's one reason he recently wrote a children's book, "Gas Trees and Car Turds," explaining climate change in simple, unexcitable terms.

The good news, he said, is that if there is a geo-engineering solution to climate change, or a solution involving carbon sequestration, it will probably be developed by people in the oil and gas industry who understand the science. Asked what would happen if CO2 emissions were stopped at present levels, Johnson said he didn't know.

Carbon dioxide is slow to dissipate - CO2 from the first Model-T is still in the atmosphere, he said - so the effects of it will be with us for a long time in any case. It will probably be up to people the age of his children to decide whether to cap CO2 levels at, say, 500 or 1,000 parts per million, he said.

"It's going to be an interesting 20 or 30 years ahead of us," he said.

Johnson also noted that there has been some debate about whether rising temperatures increase levels of CO2 or whether rising CO2 levels bump up temperatures. In reality, he said, temperatures and CO2 are intimately related, acting on each other in ways that aren't completely understood.

But the recent dramatic spike in human-caused CO2 levels is unprecedented and points undeniably to more warming ahead, he said.

"It would seem to be foolish not to respond to that empirical observation," he said.

Contact Ed Kemmick at ekemmick@billingsgazette.com or 657-1293.

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