PROVIDENCE, R.I. [Brown University] — When it comes to greenhouse gases, methane is one the biggest contributors. Not only is it massively abundant — it’s about 25 times more potent than carbon dioxide at trapping heat in the atmosphere.
That makes tracking methane emissions critically important, and nowhere more so than in the Arctic, which is now the fastest warming part of the globe. A new study conducted at Brown University helps shed light on the actual atmospheric methane emissions from Arctic lakes and wetlands, which are major producers of the gas but remain largely unmapped.
Using unprecedented high-resolution satellite and airborne imagery from NASA — harnessing the technology to overcome barriers posed by the region’s sheer size and numerous natural land formations that are major methane producers — a pair of researchers produced new estimates and found that these unmapped lakes are not the great methane emitters that previous research has made them out to be. Instead of contributing about 40% of the region’s methane emissions, small unmapped lakes contribute only about 3%, according to the study.
“What the research has shown is that these smaller lakes are the greater emitters of methane on a per area basis, which means even that though they take up a small amount of the landscape they have a disproportionate level of emissions,” said Ethan D. Kyzivat, who led the study as part of his Ph.D. at Brown. “Traditionally, we haven't had a good picture of how much area they take up, but this new high-resolution dataset helped us scale it up to finally make those estimations much more accurately.”
These new findings, described in Geophysical Research Letters, contradict close to 15 years of research based on older datasets with much lower resolution quality. In the older data, the number of small lakes that could be seen were statistically extrapolated to produce estimates for the region on the total number of small unmapped lakes and how much methane they emitted.
The new analysis of the aerial imagery showed the researchers, including Brown professor Laurence C. Smith, that there are far fewer small, unmapped lakes than were previously estimated, greatly reducing the cumulative amount of methane they were thought to emit.