Exploding methane gas bubbles

NARRATOR: This region may hold the key to the future of our climate, as global warming takes hold. It’s one of the remotest and coldest places on the planet. For much of the year, temperatures fall to –40°C, freezing everything solid, including the ground.

But hidden in this frozen ground, known as permafrost, is a potential climate disaster. It’s called methane, and it’s a far more powerful greenhouse gas than carbon dioxide. The danger is, if the permafrost was to melt as a result of global warming, it could release methane on a massive scale.

Ecologist Katey Walter believes that it’s already beginning to happen. She’s studying the lakes that cover the region. 

DR KATEY WALTER, University of Alaska Fairbanks: The permafrost contains a very large pool of organic carbon. It’s dead plant matter. And that dead plant matter, when it is thawed out in the bottoms of the lakes, it’s a food source for organisms that produce methane. They eat the dead plant matter, and they burp out methane. Methane is the by-product of their digestion. And it bubbles up from the lake sediments and gets trapped in the ice.

NARRATOR: If Katey’s right, then the ice should be full of bubbles of methane. To find out the extent of the problem, Katey and the assistant head out to the middle of the frozen lake. First they remove the snow covering the ice, before using tea from their flask to clear the surface.

DR KATEY WALTER: You can actually see the bubbles trapped in the ice. They’re beautiful. The ice can be crystal clear with little bubbles, almost like little coins stacked on top of one another. And what’s happening is that as the bubbles are released from the sediments beneath, they wobble up through the water column, and they hit the ice that’s forming and thickening overhead. And so the bubbles actually freeze in place.

NARRATOR: The trouble is, if these are bubbles of methane, it won’t stay trapped in the ice for long. When the ice thaws in spring, the gas will escape. There’s one sure way to check just how much methane is in these bubbles, because it’s highly flammable.

DR KATEY WALTER: When you poke a hole into those pillows of methane, you get this stream of gas that comes out. And depending on the size of the hole you can get a very large stream of gas. So when you light that, you get a very large flame. And you have to be careful, because sometimes you can singe your eyebrows.

NARRATOR: These bubbles can be found all over the place. There must be enormous amounts of methane being released here. And that has serious implications.

DR KATEY WALTER: The methane then heats the atmosphere, contributing to global warming, which then causes more permafrost to melt and more methane to be produced, and it’s sort of this vicious feedback cycle. We think of this permafrost here as like a time bomb waiting to go off.