They say recent observations indicate that the air above Alaska "may already hold the first signs of a regional increase in greenhouse gas emissions" that could contribute to global climate change.
"Recent observations could be isolated cases or part of a vast regional change in emissions that could accelerate climate warming to a more dangerous pace. We don't know yet," said Colm Sweeney, of NOAA's Earth System Research Laboratory in Boulder, Colorado. "We're eager to find out."
Sweeney heads a NOAA aircraft project that samples greenhouse gases around the country. In addition, the lab monitors the gases from 60 sites worldwide.
"It's important to locate natural sources and measure how much methane and carbon dioxide are being released now so we can watch for signs of increasing emissions," said Sweeney. "Methane is 25 times more powerful than carbon dioxide as a greenhouse gas, though its lifetime in the atmosphere is significantly shorter. We're especially interested in those sources."
Coast Guard personnel at Kodiak, Alaska, prepare a C-130 aircraft for a flight carrying NOAA instruments north to the Arctic Circle. (Photo courtesy NOAA)
"North of the Brooks Range, the tundra is not yet melting, but south of the range, partial melting is already occurring," Sweeney said. "The south will give us clues to what's likely to happen north of the range in the coming years."
Sweeney and his team want to know if in the future the warming tundra will dry out, exhaling large amounts of the greenhouse gas carbon dioxide. Or, they wonder, will melting ice form pools and lakes, allowing microbes to eat buried organic matter, burping up huge amounts of methane, another greenhouse gas.
Earlier research documented large bubbles of methane near Arctic lakes. Satellite sensors revealed similar lakes in other areas, but whether those lakes produce methane is unknown.
Last year research vessels in the Arctic Ocean observed methane vents releasing the gas from the ocean floor. Perhaps these vents have been there all along, undiscovered, say the scientists, or they could have developed recently.
Coast Guard Arctic flights using a C-130 maritime surveillance aircraft began in the fall of 2007. When the base in Kodiak offered to carry air-sampling instruments on the twice-monthly flights out of Kodiak over the Brooks Range to Barrow in the Arctic Circle, NOAA scientists jumped at the chance.
NOAA scientists replaced one of the plane's windows with a plate for air inlets that lead to onboard instruments measuring greenhouse gases and ozone in real time. One instrument will measure methane and carbon dioxide every other second.
Air is also stored in glass flasks that are sent back to the lab in Boulder. There, scientists will analyze the air to understand the distribution of almost 40 other pollutants and trace gases.
The flights will typically stop in Galena, south of the mountain range, and at Kivalina on the north coast, ending up at Prudhoe Bay. NOAA has operated an atmospheric observatory at Barrow, about 200 miles west of Prudhoe, for decades.
"So far profiles north of the Brooks range indicate significant enhancements in methane emissions near the surface," said Sweeney, "but it's uncertain whether those are local emissions from human activities or outgassing from natural sources."
Scientists will search for natural sources of methane and carbon dioxide as well as methane sources from human activities, such as oil drilling in Prudhoe Bay.
Gathered over three seasons, the data will help NOAA map out natural emissions sites, estimate their outflow, and set benchmarks for future changes.
The Coast Guard said in a statement that the flights "test capabilities, build Arctic operational expertise, identify challenges, survey sea ice and monitor vessel traffic in U.S. Arctic waters."
Copyright Environment News Service, ENS, 2009. All rights reserved.