Every year, 6,000 flasks arrive at a laboratory in Boulder, Colorado. Inside each is a sample of air, taken from one of a chain of 50 monitoring stations that spans the globe. Together, these samples could help answer one of the most important questions facing the planet: why is there so much methane in the atmosphere?
Blue and black canisters filled with air from Algeria, Alaska, China and Samoa are lined up ready for testing. “We collect these flask samples, then they come back here,” says Ed Dlugokencky, a chemist at the Global Monitoring Laboratory, run by the US National Oceanic and Atmospheric Administration.
The laboratory measures the levels of different gases inside the samples, from carbon dioxide to nitrous oxide and sulphur hexafluoride, compiling a meticulous record that forms the basis for major climate models. About 15 years ago, its researchers observed an uptick in atmospheric methane, a potent greenhouse gas with a warming impact 80 times greater than CO₂.