Volume 1, Issue 6
Chilling News About Glaciers
Every couple of years or so, Kurt Cuffey spends two months in Antarctica conducting fieldwork. (courtesy the researcher)
When most people look out over the Golden Gate Bridge, they're awe-struck by the majesty of the San Francisco Bay. Not UC Berkeley professor Kurt Cuffey. Staring out at the Pacific Ocean, the first thing that pops into his mind, he says, is the sea level. Meanwhile, visions of glaciers dance in his head. Cuffey, who last month was named one of Popular Science magazine's "Brilliant 10" for 2004, studies polar ice sheets to understand the history of climate change and predict future shifts in our planet's physical environment.
"The polar ice sheets are the primary control on global sea levels and also impact the temperature of the planet quite profoundly," says Cuffey, a professor in both the Department of Earth and Planetary Science and the Department of Geography.
The massive ice sheets are affected by the climate in several ways, Cuffey explains. Snowfall causes them to grow while a rise in temperature leads to melting. Meanwhile, the ice sheets flow like a viscous fluid, similar to "honey dumped on a counter," Cuffey says. For example, the Antarctic ice sheet, more expansive than the continental United States and several miles deep, moves hundreds of meters annually. While the size of the ice sheet is affected by temperature, it's also part of a climatic feedback loop.
"The snow covering the sheets causes them to be very reflective," Cuffey says. "If the climate cools and the ice sheet grows, it will reflect more sunlight causing a further cooling of the climate. With global warming, the inverse is true."
In Antarctica during the summer, there are periods of 24-hour sunlight. In winter, there are weeks where the sun does not rise. (courtesy the researcher)
Cuffey employs several techniques to gather his data, most of which involve suffering the sub-zero centigrade temperatures of Antarctica. His survey work involves mounting Global Positioning Systems on glaciers to monitor the ice flow and collecting atmospheric data from an array of weather stations. Cuffey's most interesting insights often come from ice cores, samples extracted by drilling a mile-long bore hole into a glacier. Bubbles trapped in the ice contain atmospheric air from tens of thousands of years ago.
"The ice and the bubbles act as chart recorders of climate, atmospheric composition, and other environmental properties over periods of millennia," he says.
For example, by chemically analyzing the ice cores and temperature readings taken from a Greenland bore hole, Cuffey and his colleagues determined that in the 20,000 years since the last ice age was its coldest, the Greenland ice sheet warmed approximately 15 degrees centigrade, much more than previously thought. Amazingly, 10 degrees of that warming occurred over a single decade. Cuffey's results hammered home the fact that climate change can occur much more abruptly than most scientists suspected.
When he's not trudging through the snow, Cuffey crunches his data on a computer to create numerical models of ice sheets. These mathematical models of ice flows reveal how the ice sheets behave over time in response to climate and sea level changes. The models are also essential in predicting future climate changes. For example, Cuffey asks, how would the ice sheet change if global warming raised the temperature by, say, five degrees centigrade?
The recent Hollywood blockbuster "The Day After Tomorrow" depicts global destruction caused by a nearly-instantaneous ice age. While the film is based purely on science fiction, Cuffey says that the Greenland ice sheet could plausibly melt in the next few thousand years, raising sea levels enough to drown most major coastal cities.
"What if we determine that global warming in the next century could induce a rapid climate change that will decimate some societies around the globe?" Cuffey says. "How does society act on that information? Part of what I'd like to do is provide data that can help determine public policy."