A Camera That Sees Methane
By Elizabeth Preston
Swedish scientists have built a camera that makes methane gas visible. The tool could help researchers study greenhouses gases and answer tricky questions about climate change. It’s also good for visualizing cow farts.
Magnus Gålfalk of Linköping University explains that the camera works using infrared spectroscopy. Called “hyperspectral imaging,” the method simultaneously captures a spectrum of infrared light for every pixel in a photo. Many gases absorb infrared light, Gålfalk says, not just methane (CH4). But the camera is fine-tuned to see the signature of methane gas.
In the picture above, the purple plume is methane the researchers released from their lab to test the camera. They also tried taking pictures of a waste incineration plant, a heap of sewage sludge, and a barn with 18 cows inside (the red area is methane):
Getting a better grasp on CH4 matters because methane is a powerful greenhouse gas. Molecule for molecule, it warms the earth 86 times more effectively than carbon dioxide does, Gålfalk says. But scientists don’t have a good understanding of how methane moves through the environment.
To measure methane gas on a very small scale, scientists can collect an air sample in one place and test it for methane back in the lab. Satellites in space can also measure methane on a regional or even global scale. But Gålfalk says the camera fills a gap between these two scales. It also lets researchers pinpoint sources of methane gas and see how it’s moving.
In the image below, methane rises off a lake called Lillsjön in Stockholm. That, or some cows have been visiting.
Images: from Gålfalk et al.
Gålfalk, M., Olofsson, G., Crill, P., & Bastviken, D. (2015). Making methane visible Nature Climate Change DOI: 10.1038/nclimate2877