Oak Ridge National Laboratory researchers and director deliberate on disappearing glaciers
Glaciers thrice as tall as the Empire State building calve, crumble, and careen into the sea during Chasing Ice, a film in which National Geographic photographer James Balog chronicles the rapid disappearance of Arctic ice as Earth’s average temperature rises. In 2007 Balog launched his Extreme Ice Survey by placing time-lapse cameras in Alaska, Montana, Iceland, and Greenland to compress years into seconds and capture the death throes of ancient glaciers. Because atmospheric carbon dioxide cannot be seen with the naked eye, Balog chose to photograph ice, the first place the effects of greenhouse-gas increases could be witnessed, “to make the invisible visible and tangible,” said Chasing Ice director/producer Jeff Orlowski. After the February 1, 2013, screening of the movie at a Knoxville theater, Orlowski was on hand with four scientists from the Climate Change Science Institute (CCSI) at Oak Ridge National Laboratory (ORNL) to answer a range of audience questions from how a gas that makes up less than 1 percent of the atmosphere can exert such a powerful effect to whether glaciers are goners.
When asked about the consequences of Greenland greening with the disappearance of ice sheets, CCSI Deputy Director Benjamin Preston, who moderated the discussion, replied that the complete melting of the Greenland ice sheet would unlock about 7 meters (22 feet) of global sea-level rise. “That’s basically a level of oceans that none of us has ever seen,” Preston said.
Last year CCSI’s Kate Evans, who develops high-resolution models of continental-scale ice dynamics, simulated the behavior of all of Greenland’s glaciers on ORNL’s Jaguar supercomputer. She told the audience that massive meltwater from Greenland can affect the salt density and temperature gradients that drive global ocean circulation patterns. “If you have a lot of ice-sheet melt into the North Atlantic, you can shut down the warm-water conveyor belt and thus shut down warm-air transport up to northern Europe,” she said. “So you can actually see cooling in that region even though the global warming itself is happening.”
Orlowski said the consequences of climate change encompass more than just ice. If a sequel to Chasing Ice ensues, time-lapse photography may also reveal evidence of climate change in declining forests, advancing deserts, raging wildfires, shifting croplands, and migrating species. Meanwhile, Balog plans to expand his ice survey by adding cameras in Antarctica, Argentina, and Mount Everest as well as additional sites in the Arctic.
The higher sea levels produced by melting glaciers increase the devastation of storm surges. “Events like [Hurricane] Sandy are going to really start waking people up,” said Orlowski, pointing out once-in-100-years megastorms may happen every few years. Preston, who explores potential impacts of climate change on society, noted, however, that such events may prompt local rather than global action: “The lessons we’re going to learn from Sandy are going to be lessons learned by New York and New Jersey, and they’re going to be built around questions like how do we build a more resilient community so that when these events happen, we don’t see tens of billions of dollars in losses?”
An audience member asked how carbon dioxide, which makes up less than half of 1 percent of the atmosphere, can exert such a dramatic effect. “[Greenhouse] gases are transparent to incoming ultraviolet radiation, and they trap outgoing infrared radiation, and they’re very good at that,” responded CCSI’s Tom Boden, who leads ORNL’s Carbon Dioxide Information Analysis Center, which collects, archives, and analyzes data about greenhouse-gas sources and concentrations on behalf of the international community. “Even though they’re only present in the atmosphere in small amounts, relatively speaking, to more common, abundant elements, they’re incredibly powerful heat trappers.”
Another theatergoer asked what fields students interested in climate change should pursue. “There’s this whole diversity of folks who are working on this particular issue, from the science—whether it’s biology or chemistry or physics—to economics and social science and moral philosophy,” said Preston. “Climate change is truly a multidisciplinary and interdisciplinary endeavor,” Boden agreed. “Oceanography, climatology, chemistry, biology, political sciences, social sciences, computer sciences—we need talent in all of those areas to continue to tackle not only climate change, but also the next generation of environmental problems that are associated, like the acidification of the oceans.”
It’s never too early to learn about climate, climate variability, and climate change. Third-grade classes in Knoxville and Barrow, Alaska, are among the followers of a blog by climate scientists conducting large-scale field studies in Alaska. CCSI’s Stan Wullschleger leads the Next-Generation Ecosystem Experiment to model, from bedrock to vegetative canopy, an ecosystem containing vast stores of trapped carbon. As permafrost thaws, organic matter decomposes and releases carbon dioxide and methane, which is approximately 25 times more powerful than carbon dioxide as a warming agent.
“Ice is a prevalent form of all Arctic systems, even terrestrial systems that we see in the boreal forests and the Arctic tundra,” Wullschleger told the audience. “We have high amounts of ground ice and permafrost and ice-wedge polygons that dominate the tundra on the north slope of Alaska. These too are systems that are vulnerable to increases in temperature.” He described the fate of ponds that form in low-lying areas when ice melts. “These thaw lakes over the last 50 years are shrinking and disappearing,” he said.
“Are we at the point of no return?” asked an audience member. Boden noted background tropospheric carbon dioxide levels have risen to more than 390 parts per million, mainly due to burning of fossil fuels, and global emissions of carbon are now about 10 billion tons annually. Keeping global warming below 2 degrees Celsius (approximately 4 degrees Fahrenheit) over the next century is unlikely, he said. “We’re on an emissions trajectory where 3, 4, possibly 5 degrees Celsius [about 6, 8, or 10 degrees Fahrenheit] is probably more likely,” Boden said. “Are we at the point of no return? Don’t know. But it would be very, very difficult right now to get ourselves off our current trajectory, especially as we’re seeing very large growth in fossil fuel emissions from countries that are sitting on vast reserves of coal right now with very large populations and very daunting future energy requirements.”
The National Geographic Channel recently purchased the television rights to Chasing Ice and is scheduled to air the documentary in April. The movie is now showing in theaters worldwide.—by Dawn Levy