SUMMIT STATION, Greenland -- At first glance, this research station on the highest point of Greenland's vast ice sheet doesn't look like much.
A scattering of trailers perch on stilts high above the snow, with a neat grid of small yellow tents off to one side. There's a tall metal tower, a few outhouses. A pile of fuel bladders stands in stark contrast next to the carefully groomed ice runway.
But this nondescript outpost is a magnet for scientists trying to answer some very big questions. Do clouds and tiny aerosol particles help warm or cool Greenland's ice and the air above it? How fast is the climate here changing? How quickly is Greenland's ice sheet melting?
Researchers established the first camp here in 1989, at the start of an international effort that drilled the 3,053-meter-long Greenland Ice Sheet Project-2 ice core, retrieving a record of climate over the previous 110,000 years.
That project ended in 1993. It wasn't until nearly a decade later, in 2000, that the National Science Foundation turned the camp perched on the apex of Greenland's ice, 2 miles above bedrock, into a year-round research hub. The station, manned by a six-person crew in winter, hosts up to 50 people at a time during the bustling summer research season.
This year, Summit's list of long-term visitors includes Brandon Strellis, an environmental engineering graduate student from the Georgia Institute of Technology studying how aerosols influence how much energy is reflected and absorbed by Greenland's ice -- and where those particles are coming from.
One aerosol, black carbon, is of increasing concern for Arctic nations worried about the pace of climate change in the far north, which is warming twice as fast as the global average. Sooty particles of black carbon, produced by burning fossil fuels, wood and dung, warm the atmosphere by absorbing heat from the sun. And when they land on Greenland's snow and ice, their ability to absorb heat from sunlight increases surface melting.
Probing mysteries of soot and clouds
A study released in May by the Arctic Council suggests that, while countries below 40 degrees north latitude collectively contribute the lion's share of the world's black carbon output, Nordic countries' soot is the most damaging, because it has the shortest distance to travel to the Arctic.
Strellis said the project he's working on, organized by Georgia Tech professor Michael Bergin, seeks to determine whether black carbon is reaching the interior of Greenland's ice, and how it gets there.
"Long term, policy-wise, if we can say what percentage is from [man-made] sources, policymakers can see where to cut pollution," said Strellis, who spent most of May, June and July at Summit collecting and analyzing snow samples for the project.
Across camp, in a trailer on skis known as the "Mobile Science Facility," researchers are training their eyes to the sky. The tiny shelter is jammed with expensive science equipment designed to measure the clouds high above.
"Clouds are one of the major feedbacks in cooling and heating the surface" of the ice, said Nate Miller, an atmospheric science graduate student at the University of Wisconsin, Madison. But it's not clear which effect predominates in the Arctic, he explained, since different types of clouds have different effects on climate, depending on whether they're made of ice or snow, whether they're thick or thin, and how high they sit in the atmosphere.
Next door, in the "Temporary Atmospheric Watch Observatory," or "TAWO," the National Oceanic and Atmospheric Administration tracks the level of greenhouse gases and ozone-depleting chemicals in the atmosphere.
"When we figure out how to measure to our standards, we never stop measuring," said Brian Vasel, field operations manager for NOAA's global network of observatories, explaining his agency's philosophy. "We're the world standard for tracking carbon dioxide, carbon monoxide, methane and sulfur hexafluoride."