Methane, Permafrost, and CARVE Mission Update
June 11, 2013
I had interviewed CARVE mission scientist Dr. Charles Miller at last year’s AGU Fall Meeting. The resulting video is one of my most unsettling, above.
June 11, 2013 — Flying low and slow above the wild, pristine terrain of Alaska’s North Slope in a specially instrumented NASA plane, research scientist Charles Miller of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., surveys the endless whiteness of tundra and frozen permafrost below. On the horizon, a long, dark line appears. The plane draws nearer, and the mysterious object reveals itself to be a massive herd of migrating caribou, stretching for miles. It’s a sight Miller won’t soon forget.
“Seeing those caribou marching single-file across the tundra puts what we’re doing here in the Arctic into perspective,” said Miller, principal investigator of the Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE), a five-year NASA-led field campaign studying how climate change is affecting the Arctic’s carbon cycle.
“The Arctic is critical to understanding global climate,” he said. “Climate change is already happening in the Arctic, faster than its ecosystems can adapt. Looking at the Arctic is like looking at the canary in the coal mine for the entire Earth system.”
Aboard the NASA C-23 Sherpa aircraft from NASA’s Wallops Flight Facility, Wallops Island, Va., Miller, CARVE Project Manager Steve Dinardo of JPL and the CARVE science team are probing deep into the frozen lands above the Arctic Circle. The team is measuring emissions of the greenhouse gases carbon dioxide and methane from thawing permafrost — signals that may hold a key to Earth’s climate future.
Over hundreds of millennia, Arctic permafrost soils have accumulated vast stores of organic carbon — an estimated 1,400 to 1,850 petagrams of it (a petagram is 2.2 trillion pounds, or 1 billion metric tons). That’s about half of all the estimated organic carbon stored in Earth’s soils. In comparison, about 350 petagrams of carbon have been emitted from all fossil-fuel combustion and human activities since 1850. Most of this carbon is located in thaw-vulnerable topsoils within 10 feet (3 meters) of the surface.
But, as scientists are learning, permafrost — and its stored carbon — may not be as permanent as its name implies. And that has them concerned.
“Permafrost soils are warming even faster than Arctic air temperatures — as much as 2.7 to 4.5 degrees Fahrenheit (1.5 to 2.5 degrees Celsius) in just the past 30 years,” Miller said. “As heat from Earth’s surface penetrates into permafrost, it threatens to mobilize these organic carbon reservoirs and release them into the atmosphere as carbon dioxide and methane, upsetting the Arctic’s carbon balance and greatly exacerbating global warming.”
The CARVE science team is busy analyzing data from its first full year of science flights. What they’re finding, Miller said, is both amazing and potentially troubling.
“Some of the methane and carbon dioxide concentrations we’ve measured have been large, and we’re seeing very different patterns from what models suggest,” Miller said. “We saw large, regional-scale episodic bursts of higher-than-normal carbon dioxide and methane in interior Alaska and across the North Slope during the spring thaw, and they lasted until after the fall refreeze. To cite another example, in July 2012 we saw methane levels over swamps in the Innoko Wilderness that were 650 parts per billion higher than normal background levels. That’s similar to what you might find in a large city.”