by Rachel Shockley | May 31, 2015 3:15 pm
Scientists from several agencies, including NASA and the National Oceanic and Atmospheric Administration, are taking a closer look at the Four Corners after a European satellite detected the largest concentration of methane in the United States hovering in the region.
Teams of researchers recently traveled to the area to confirm the findings, and to pinpoint the specific sources of the potent greenhouse gas.
The initial field campaign, called TOPDOWN (Twin Otter Projects Defining Oil Well and Natural gas emissions) 2015, was planned by scientists from the Cooperative Institute for Research in Environmental Sciences at the University of Colorado-Boulder, the University of Michigan and NOAA. Scientists from NASA and other organizations later joined in the study, lending additional equipment, funding and expertise.
From 2003 and 2009, a European Space Agency satellite measured a persistent atmospheric hotspot of methane above the intersection of Colorado, New Mexico, Arizona and Utah. The isolated cloud of methane was much larger than any other source of methane in the United States observed by the satellite, but the satellite images did not reveal the sources of the methane gas. Researchers suspect that some of the methane did not originate in the Four Corners, but was blown in from neighboring regions.
Eric Kort, a leading climate expert and a professor of atmospheric science with the University of Michigan, was the lead author of the study that revealed the methane hot spot. Kort is now part of the TOPDOWN 2015 study and traveled to the area to help gather new data.
“I like having environmental discussions based on actual observations,” said Gabrielle Pétron, a scientist from the Cooperative Institute for Research in Environmental Sciences at CU-Boulder, working in NOAA’s Earth System Research Laborator y. As part of the ground cmapaign, Pétron captured original data on methane seeping from the ground in the Four Corners. Eryka Thorley, a graduate student intern for NOAA, joined her.
Methane leaks into the air from both natural sources and human activities. “The largest natural sources of methane in the world are wetlands,” Pétron told the Free Press. However, human activities now make up more than half of all methane emissions.
NOAA wants to better understand human-caused methane emissions, and monitoring has intensified in the United States in the past 10 to 15 years, said Pétron.
In the United States, the main anthropogenic sources of methane include natural-gas and petroleum development; ranch animals, which produce methane as they digest food; landfills; and coalmining, according to the Environmental Protection Agency.
In a recent joint press release about the TOPDOWN 2015 study, scientists stated that likely sources for the methane hot spot in the Four Corners are oil and gas activities, including those related to extracting coalbed methane. They also suspect that active coal mines and natural methane seeps, such as the Fruitland coal outcrop at Carbon Junction in Durango, contribute to the elevated methane levels.
Locally, there are more than 20,000 active oil and gas wells, and there are easily as many inactive wells, Pétron said. There are also several active coal mines, coal-burning power plants, natural-gas compressors and processing plants, gas seepages from coal outcrops, landfills, farms and ranches, all potentially contributing methane emissions.
Pétron is quick to point out that the hot spot does not pose an immediate human health risk. Methane is naturally present in the air and is not toxic. Although methane is not entirely harmless, the situations that would endanger human health do not apply to the hot spot.
According to the U.S. National Library of Medicine, methane, the primary component of natural gas, is a colorless, odorless and tasteless gas. When concentrated, it is highly flammable and explosive and can cause suffocation if inhaled, by displacing oxygen in the lungs. Methane gas is one of the reasons miners traditionally brought canaries into coal mines.
However, when methane is released into the atmosphere it traps heat like glass in a greenhouse. Methane accounts for approximately 15 percent of global annual greenhouse-gas emissions, according to figures cited in President Obama’s recent Climate Action Plan. The lighter-than-air gas, along with other greenhouse gases such as carbon dioxide, ozone and water vapor, captures heat from the sun’s rays before it can radiate into space. The more greenhouse gases that are in the atmosphere, the more earth’s temperature rises.
According to the EPA, methane traps significantly more heat than carbon dioxide. If compared directly over 100 years, methane would trap 25 times more heat than carbon dioxide.
In addition to methane’s role as a heat-trapping gas, scientists have additional concerns. The gas contributes to ground-level ozone, a major cause of smog and an EPA-regulated pollutant that causes coughing, breathing difficulty and lung damage.
Also, air pollutants such as benzene and hydrogen sulfide often seep out along with methane. When the air samples from the TOPDOWN 2015 study are analyzed, scientists will be able to identify if additional compounds such as these are escaping into the air in the Four Corners.
Conversely, when natural gas, which is mostly methane, is burned, it produces fewer nitrogen oxides and carbon dioxide than coal or oil for each unit of heat released, according to the EPA. These qualities make it a popular fuel for heating, cooking, generating electricity and for industry.
Thorley admits that the dynamic between people and climate change is complex. “The challenge is finding a specific focus that you can work on.”
“I’m really interested in air quality because [air] is the most essential thing to life,” Thorley said.
The Four Corners Air Quality Group organized a public science forum in Farmington, N.M., on April 17 to coincide with the new research. The group held the event to inform the public on what research has been done and what scientists have learned about the hot spot. Representatives from NASA, NOAA, the University of Michigan, the Western States Air Resources Council and the Western Regional Air Partnership — two regional groups focusing on air-quality issues — shared information about ongoing studies and what they hope to discover by gathering additional scientific measurements.
Attendees were invited to ask questions and to inspect the instruments in the NOAA and Institute for Arctic and Alpine Research (INSTAAR)- designed mobile labs. As part of the study, scientists used the vehicles to investigate large methane plumes observed by aircraft, and assist in attributing the methane to a specific source and measuring it near the surface.
Scientist drove the mobile labs on public roads throughout the San Juan Basin in April, conducting surveys. The special equipment measured methane, water, carbon dioxide and carbon monoxide in the air every two seconds. Onboard computer screens displayed the real-time measurements.
When scientists encountered a methane source, they positioned their mobile lab downwind and allowed their instruments to collect data. They also gathered samples of air in glass vials to be analyzed later for chemical compounds and isotopic chemical fingerprints at the NOAA and INSTAAR laboratories in Boulder.
According to Pétron, chemical isotopes vary depending on the source of methane, and are unique. For example, the isotopes found in a methane plume at an animal feed lot will be different from the isotopes from a landfill, or an oil and gas operation.
By isolating isotopes, scientist can more closely trace methane back to a specific point source. The isotopic signature of the Fruitland coal outcrop is a well-documented example that can be used to determine what is in the air, said Pétron.
In order to better understand what is coming from where, several aircraft from NOAA and NASA made a second set of measurements from the air during the month of April. The planes collected information about methane, air quality and climate. The planes were set to cover the 2,500 square miles of the San Juan Basin, and flew in a variety of conditions, collecting data from varied elevations throughout the study.
Kort said they had a number of good flight days, and that allowing for bad weather was one of the reasons they allotted for a full month in the air.
“We can see indications of different chemical fingerprints,” Kort said. “Often sources for methane emissions are co-located, so geographically they are hard to distinguish. It’s tricky to pull it apart.”
Kort went on to explain that many coalbed methane and gas wells are near each other, but are drilled to different depths to extract the different fuels, which yield different fingerprints.
The team wrapped up its research at the end of April, and expects the results of the study to be published, after a peer review, in a little over a year. “We have such a rich data set, there might be studies coming out for sometime afterward,” Kort said.
Kort said all of the data collected will go to the public. “If someone wants to use data I collected, that’s great.”
“The air is a shared resource — with everyone in the world.” Pétron said. “When we talk about methane, it is a long-term problem.”
The team of scientists hopes that tracking and measuring methane emissions more accurately in the United States will give stakeholders and decision- makers the information they need to plan for the future.
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