Casey Campbell/Gazette-Times Ed Brook holds up a small section of an ancient ice core filled with tiny bubbles of trapped air from when it was originally frozen. Scientists hope to better understand the Earth’s climate patterns by studying these atmospheric samples.

OSU researcher studies cylinders of ancient ice to learn about greenhouse gases from the past, make predictions for the future

Understanding the Earth’s historical climate patterns helps scientists put today’s temperatures and levels of greenhouse gases in perspective — and make predictions about the future.

But when looking back in time before the advent of the thermometer, scientists must rely on environmental clues to gauge the weather 100,000, 200,000, even 650,000 years ago.

Ed Brook, professor of geosciences at Oregon State University, looks at the tiny air bubbles trapped in ice core samples to conduct his climate analyses.

“(Ice coring is) pretty unique in the climate research world because we can tell without a doubt that greenhouse gases are higher today than they were prior to the Industrial Revolution,” Brook said. “You start to really see that the modern atmosphere is really different from the natural atmosphere.”

Brook, who serves as co-chairman of the International Partnerships in Ice Coring Sciences, recently gained worldwide attention for his article in the November issue of Science.

Brook reviewed for the journal the research conducted by scientists in the European Project for Ice Coring in Antarctica.

These researchers studied gases trapped in 650,000-year-old ice, which added 210,000 years of data about the Earth’s atmospheric patterns and changes to the already existing bank of information.

Brook, along with colleagues at OSU and the University of California, San Diego, studies ice cores in Antarctica and Greenland.

To obtain ice cores, scientists drill and extract tubular samples of ice. They then cut off slices, usually about 2 inches thick and 3 inches in diameter, to study. The ice is transported to places such as OSU in refrigerated containers.

When Brook holds a slice up to the light, tiny bubbles trapped in the ice sparkle. The bubbles are actually ancient air that he isolates and studies.

First, Brook places the sample inside a vacuum chamber. He inundates it with alcohol chilled to 40 degrees below zero Celsius. This keeps the ice frozen.

Then, he uses a vacuum pump to suck the lab air out of the chamber. Now all that remains is the ice and the ancient air trapped inside it.

Next, Brook surrounds the chamber with warm water to melt the ice, causing the air to release and hover above the water.

Using a gas chromatograph, Brook can then measure the levels of greenhouse gases such as carbon dioxide and methane present in the ancient air.

One of his current projects focuses on the Pakitsoq Site on the west coast of Greenland. He hopes to find samples large enough that he can measure levels of carbon-14, a radioactive isotope used by archaeologists and geologists for dating purposes.

Ice core research has demonstrated that greenhouse gases have increased since humans started building land fills, burning fossil fuels and cutting down forests, Brook said.

The studies have also demonstrated a relationship between high temperatures and high levels of greenhouse gases.

Warm periods naturally occur on the Earth every 100,000 years or so, and last anywhere from 10,000 to 30,000 years, Brook said. The globe is about 10,000 years into the latest hot phase.

During these temperature peaks, greenhouse gases increase, which in turn seems to drive temperatures even higher, Brook said. Current levels of methane and carbon dioxide far exceed those found in historic ice samples, and this trend shows no signs of reversing.

“We should be paying attention,” Brook said, adding that if increased greenhouse gases lead to more global warming, then the world could face obstacles such as sea level changes, dangerous heat waves, the extinction of some heat-sensitive species and possibly more frequent storms and hurricanes.

Andreas Schmittner, assistant professor of oceanography at OSU, said ice core research, which allows scientists to look farther into the past, will aid him in creating computer-generated climate models.

“Past records are very important for us because they tell us the exact carbon dioxide and methane levels in relation to climate changes,” he said, adding that understanding the past helps him make predictive models for the future.

Schmittner said today’s greenhouse levels of unprecedented highs will likely lead to global warming, of which the exact consequences on the ocean biosphere, the land and its vegetation and the Earth’s water cycle are not yet known.

Another view

Not all scientists view global warming as an impending danger for which humans are primarily responsible, though.

State climatologist George Taylor, who also works at OSU, calls Brook’s research “commendable.” However, Taylor believes natural factors such as changes in sunlight, ocean circulation and volcanoes play a more dominant role in rising temperatures than do human-produced greenhouse gases.

Taylor said ice core research gives proxy climate measures that indicate a general correspondence between increased greenhouse gas emissions and increased temperatures, but he points to the 1950s, ’60s and ’70s — decades when greenhouse gases were on the rise, but temperatures declined — as flaws in an absolute cause-and-effect argument.

Brook hopes to make his next trip to Greenland during the summer of 2007. He’s also working to develop a method of crushing ice, rather than melting it, to more-effectively analyze the carbon dioxide in ice core samples.

Mary Ann Albright covers higher education. She can be reached at maryann.albright

@lee.net or 758-9518.

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