If this comes to pass, we can anticipate increased fire severity and an even greater area burned annually, causing a further rise in the release of carbon dioxide.” Last August, Williams co-authored a New York Times editorial that warned of a multidecade “megadrought” in the American West if fossil-fuel emissions go unchecked. He wrote, “[T]here can be little doubt that what was once thought to be a future threat is suddenly, catastrophically upon us.”
spring 2013
Treading on thin ice
clark alumni magazine
18
The relationship between a warming atmosphere and wildfire outbreaks is just one example of climate-change impacts. Global warming is contributing to a very different, but equally complex response in the cryosphere — regions of the globe normally characterized by snow, ice and extreme cold. While Clark geographer Karen Frey developed an interest in climate change at an early age, colleague Alex Gardner had already completed his training as a civil engineer before he became fascinated with glaciers during a hiking trip to the ice fields of Patagonia in South America. A desire to assess the rate and volume of melt from glaciers and ice caps in polar and mountainous regions has spurred Gardner to camp out on remote, ice-covered islands in northern Canada; Frey undertakes much of her field research on melting sea ice aboard U.S. and Canadian icebreakers, and on thawing permafrost from remote field stations in East Siberia and the Alaskan North Slope. Global warming is having its greatest impact in the far northern latitudes, and understanding where and how rapidly ice is melting there, and in other frigid regions, is critical to predicting the magnitude of future environmental change across the globe. Using computer programs he writes himself, along with remotely sensed data from two satellites, Gardner can determine the amount of ice lost to melting. A Canadian by birth, Gardner is especially interested in ice melt in the Canadian Archipelago. This cluster of islands northwest of Greenland had received little attention, but a study led by Gardner
found that, outside of Greenland and Antarctica, it was the largest contributor to sea-level rise from 2007 through 2009. Results of the study were published in the prestigious journal Nature in 2011. Frey calls permafrost, which covers approximately one quarter of Northern Hemisphere land areas, “a ticking time bomb,” because of the carbon locked inside. Defined as soil or rock whose temperature remains below 0 degrees Celsius (32 degrees Fahrenheit) for at least two consecutive years, permafrost can extend several hundred meters below the earth’s surface. When permafrost thaws, it provides food for bacteria, which in the feasting process release carbon into the atmosphere as either carbon dioxide or methane. Thawing permafrost also enables the leaching of soil carbon into local streams and beyond, ultimately making its way to the coastal Arctic Ocean and impacting biophysical processes in the marine realm.
stays cool. That’s the difference between a sea ice-covered ocean and open ocean.” Last year witnessed record lows for sea ice coverage in the Arctic — and as the relative balance between ice and open water shifts in favor of the latter, increased availability of the sunlight needed for photosynthesis spurs the growth of algae. Scientists once thought that algae could not flourish under ice for lack of sunlight, but Frey was among a group of NASA scientists making recent headlines with their discovery of a huge bloom of algae doing just that. Publishing in the journals Science and Geophysical Research Letters, they found that as air warms, small pools of meltwater form atop the ice, acting as skylights to channel sunlight to the underside. “Sea ice is the huge story for these [polar] ecosystems,” Frey says. “Everything is so tightly linked in the food chain, from microscopic algae all the way to the seal, walrus, whale, and polar bear.”
Frey calls permafrost, which covers approximately one quarter of Northern Hemisphere land areas, “a ticking time bomb,” because of the carbon locked inside. Frey and Gardner also study how ice and snow function as the earth’s thermostat by reflecting the sun’s rays, thus keeping the earth from getting too hot. But as snow and ice cover contracts, and that vast whiteness is replaced by the darker, less reflective surfaces of soil, vegetation and open water, the earth absorbs more heat, which leads to more melting. “When sea ice melts,” Frey explains, “it effectively replaces some of the brightest surfaces on the planet with some of the darkest. And that amplifies the warming. It’s like standing in the middle of a black asphalt parking lot. It’s hot. But if you stand in the middle of a bright white surface, sunlight is reflected rather than absorbed and that surface
People living in Arctic regions are part of that ecosystem, too, and must scramble to adapt. “Indigenous communities in these regions are experiencing climate change and certainly know far more about climate warming firsthand than we do down here,” she notes. “It’s impacting their safety. For generations, people have understood the way to navigate sea ice in safe ways. Now environmental conditions have become incredibly unpredictable.” Frey characterizes the earth’s varied responses to climate change as an intriguing scientific experiment. “People think, ‘Oh, climate change, you’ve got it all figured out,’” she says. “But the more you learn, the more measurements you take,