Dr. Katey Walter Anthony is known for her methane studies. You’ve probably seen a picture or a video of her and a colleague or two poking a hole in lake ice and lighting the escaping gas on fire. Very Alaskan.
So about six years ago, when KUAC reporter Ravenna Koenig called Walter Anthony to confirm that a gas bubble under the grass at a local golf course was actually methane, she got her tools and went to the site.
“So, I collected some of the methane and radiocarbon dated it and found out that it was thousands of years old. And that tells us the source of the methane is thawing permafrost,” said Walter Anthony.
As the ground thaws, the stored organic matter in the soil breaks down and becomes accessible to carbon-eating microbes that produce methane.
The bulb of gas under a lawn was a surprise to Walter Anthony, because scientists had concluded that if you want to see a lot of methane leaking out of thawing permafrost, you have to go to a wetland.
“Usually we think of these anaerobic microbes as living in waterlogged environments -- lakes and wetlands. So, what was so shocking here is that we were seeing methane coming out of dry ground surfaces,” she said.
She was curious to see how widespread these “turf bubbles” might be across Alaska’s permafrost region, so when Russia’s invasion of Ukraine shelved a planned permafrost study in Siberia, she used the equipment here at home.
“So, I went into other grasslands, farm fields that had been cleared in the past, spruce forests, deciduous forests, all these places where there were signs that permafrost thaw was happening, but no water at the surface. And I repeatedly found methane coming out of these environments,” said Walter Anthony.
Walter Anthony found that these bulbs or balloons of gas were forming where the permafrost had thawed dozens of feet deep, making the stored carbon in the soil easier for the microbes to get to.
“The type of permafrost we looked at is called Yedoma, and it's the permafrost that people would associate the mammoth ecosystem from the past, from the last ice age,” said Walter Anthony.
The Yedoma soils are composed of many meters deep of decaying ancient grasslands, so there is a lot of carbon there.
“It's a unique type of permafrost. It's only about 7 percent of the permafrost region in the north, but the amount of carbon it stores is closer to 25 percent,” said Walter Anthony.
"So, Yedoma is kind of a hotspot bank account for permafrost carbon.”
In the study published last month in the journal Nature Communications, Walter Anthony and her UAF colleagues identified some upland places are actually surprisingly large methane sources.
“And in winter at a time of year, when most other methane systems are shutting down, these ones really start emitting a lot of gas.”
Walter Anthony thinks the next step is to build these new data in to climate change models and to looking for more methane-emitting Yedoma soils across the Arctic.
“It’s particularly important. We need to understand what the fate of Yedoma permafrost thaw is, if we're going to accurately predict climate feedbacks,” she said.
Starting locally, Walter Anthony plans to design a new study to asses dry land methane at the same local golf course.
