NOAA and U.S. Coast Guard Hunt for Alaskan Methane and Carbon Dioxide Sources

August 24, 2009
C-130 aircraft.

The Coast Guard personnel at Kodiak, Alaska, make ready a C-130 aircraft for a Coast Guard flight carrying NOAA instruments north to the Arctic Circle.

Recent observations have suggested that the air above Alaska may already hold the first signs of a regional increase in greenhouse gas emissions that could contribute to climate change around the globe.

To learn more about the region’s emissions, NOAA’s Earth System Research Laboratory in Boulder, Colo., has teamed up with the U.S. Coast Guard at Kodiak Island. The two partners are flying NOAA air-sampling devices aboard a Coast Guard C-130 aircraft conducting flights over the state through November.

Scientists will search for natural sources of methane and carbon dioxide — the two most important heat-trapping gases — 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 in a warming world.

“North of the Brooks Range, the tundra is not yet melting, but south of the range, partial melting is already occurring. The south will give us clues to what’s likely to happen north of the range in the coming years,” said Colm Sweeney, of NOAA’s Earth System Research Laboratory (ESRL). Sweeney is head of a NOAA aircraft project that samples greenhouse gases around the country. NOAA ESRL monitors the gases from 60 sites worldwide.

Inlets installed in a Coast Guard C-130 aircraft.

Inlets installed in a Coast Guard C-130 aircraft draw air into NOAA instruments and flasks attached inside the plane.

Billions of tons of carbon are buried in the frozen Arctic tundra, now heating up because of human-caused climate change. In the future, will the warming tundra dry out, exhaling large amounts of heat-holding carbon dioxide? Or will melting ice form pools and lakes, allowing microbes to feast on buried organic matter, burping up huge amounts of methane? Only the data will tell, say the scientists.

“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.”

When related climate affects are taken into account, methane’s overall climate impact is nearly half that of carbon dioxide.

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.

“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 Sweeney. “We’re eager to find out.”

"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."

NOAA instruments.

NOAA instruments hitch a ride aboard a Coast Guard C-130 aircraft to measure greenhouse gases across the state.

Coast Guard Arctic flights using 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. 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.

Last March, NOAA scientists replaced one of the plane’s windows with a plate for air inlets. The inlets lead to onboard instruments that measure 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.

During a recent flight, a small, driftable buoy was released from the plane. The buoy is part of the U.S. Interagency Arctic Buoy Program which collects meteorological information, tracks polar ice flows, and measures upper ocean heat content. Agencies participating in the program include NOAA, the Coast Guard, and the U.S. Navy.

The Coast Guard flights “test capabilities, build Arctic operational expertise, identify challenges, survey sea ice and monitor vessel traffic in U.S. Arctic waters,” according to a Coast Guard statement.

NOAA understands and predicts changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and conserves and manages our coastal and marine resources.