Gases scanned on the fly
Modified DC-8 helping to find way to beat heat
Scientists treating Earth as a feverish patient are giving it the equivalent of a CAT scan, targeting short-life pollutants that spur climate change to try to find a remedy that dials back the heat.
For the National Oceanic and Atmospheric Administration, University of Colorado and Harvard University scientists, this unprecedented airborne scan means looping around the planet in an instrument-packed NASA airliner that measures heattrapping greenhouse pollutants.
The aircraft — a modified white DC-8 with protruding tubes instead of windows — swooped over Boulder last week. From the Rocky Mountains to remote ocean skies, it is infusing huge amounts of data into the federal government’s climate-change predictions.
The pollutants include carbon dioxide, the main culprit causing long-term global warming, with concentrations reaching a recordhigh 405 parts per million this year, up from 403 ppm last year and 388 ppm in 2010, U.S. records show.
But the scientists are focusing on short-life pollutants that last for less than 10 years before breaking down, such as methane, ozone, and soot from burning forests and fossil fuels. These pollutants play
a rapid, aggressive role forcing up temperatures. By measuring them and pinpointing sources, the project leaders say, they’ll find options for mitigating the worst impacts of climate change, such as severe storms.
“They control the rate at which we are warming,” said CU atmospheric chemist Chelsea Thompson, a member of the team that endures repeated 14-hour stints in the plane.
“Reducing these shortlived gases will decrease the rate at which we are warming,” Thompson said. “That would be good. Humans need time to adapt.”
The scientists say they are exploring:
• How to develop a “quick-response knob” for the global climate by identifying sources of pollutants that cause the most warming so that these could be squelched strategically.
• The wafting of ozone pollution from Asia’s booming industrial zones, which contributes to the global “blanket” and, in particular, the deterioration of Colorado Front Range air quality that long has failed to meet federal health standards.
• Mixing of greenhouse gases and soot from different sources over oceans, which cover 70 percent of the planet, crucial for calculating temperature warming.
“The atmospheric measurements that the ATOM (Atmospheric Tomography Mission) takes are unavailable by any other means and are critically needed to improve the global chemistry climate models that society uses to make sound international policy decisions about what might minimize climate change,” Boulder-based NOAA atmospheric chemist Thomas Ryerson said. “It provides a reality check for the computer models we used to predict possible future atmospheric states.”
Until now, climate scientists have relied mostly on ground-based air monitor- ing stations around the planet, including NOAA’S network of 50 facilities. Climate scientists have gone airborne before on some regional investigations, such as a National Center for Atmospheric Research mission in northern Colorado to measure pollution from traffic and industry, including cattle feedlots and oil and gas facilities.
But this five-year Nasafunded project to scan the planet systematically is far more ambitious.
It relies on the NASA aircraft based at Palmdale, Calif. A team of 15 or so crew members and 30 scientists runs particle analyzers, spectrometers, sampling systems and filters at altitudes from 500 feet to 40,000 feet. The aircraft climbs as fast as 2,000 feet a minute; scientists say it feels as if they are constantly taking off or landing. The scientists stop for fuel at remote locations such as Greenland and the isolated volcanic Ascension Island in the South Atlantic Ocean.
A complete scan around Earth, including the poles, takes four to six weeks. They’ve completed two scans since they began the project in February.
They’ll embark on a third scan Oct. 1 and make a final run next year.
This flying lab sucks in air through 30 tubes, or probes, mostly about an inch in diameter, making up to 10 measurements per second.
Harvard professor Steven Wofsy initially proposed this airborne approach. Measurements of the thickness of the greenhouse-gas blanket over oceans have been lacking, a problem in assessing the potential for warming of waters, which causes storms, and other impacts of higher temperatures.
If the scans pan out as planned, national governments and United Nationsbacked groups will gain options to try immediately to mitigate climate change — before fully addressing the long-term challenge of reducing CO2, which can stay in the atmosphere for a century.
“We don’t define policy. We only inform the policymakers,” Thompson, the atmospheric chemist, said. “The best we can do is tell the people in charge that these are the big sources that we recommend looking at.”
“We’re trying to control the emissions from those sources,” such as oil and gas facilities that emit methane, she said. Methane over a decade plays a strong role driving warming, trapping 86 times more heat than CO2.
“This is not about stopping oil and gas,” she said. “It’s about coming up with strategies to prevent leaking oil and gas.”