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Go to Brilliant.org/SciShow to learn how you can take your STEM skills to the next level. {♫Intro♫}. A frozen lake looks like something out of a postcard.

Snowy banks, barren trees, perfectly smooth ice — it’s a winter wonderland. But these lakes also have secrets. And one of them is that some of them can catch fire.

Weirdly enough, the culprit here is microbes. Despite what you might think, winter lakes are full of life, especially at the microscopic scale. Some of these microbes break down algae that bloom during the summer and die in the freeze.

And in the process, they produce a lot of carbon dioxide. But one group, a type of archaea called methanogens, doesn’t just stop there: It uses that carbon dioxide to create methane. And methane is a highly-flammable gas.

This means that in some cases, when you have enough archaea and enough methane, you can actually light pockets of the lake ice on fire! And this is a thing people do! Some scientists do it to test whether the lake is really off-gassing methane instead of some other, less-flammable gas.

Basically, it’s a way to study what’s going on in a lake. But this kind of research can also be brutal. Some of these lakes are above the Arctic Circle, where winter days above freezing are rare, and nights are bitterly cold.

The weather is also unpredictable, so for many of these places, winter research isn’t just uncomfortable: It’s dangerous. But these days, more and more scientists are studying what happens to lakes and their methane levels in the colder months — and for a good reason. As the climate warms, lake ice is getting scarcer and scarcer.

Fewer lakes are freezing over completely, and those that do freeze do so for shorter amounts of time. Changes like this could have huge effects on ecosystems. But they also mean that more methane could get into the atmosphere, which would pose a pretty big climate change problem.

See, methane is also a greenhouse gas, and although its potency goes down over time, it has the potential to trap up to 86 times more heat than carbon dioxide over about a 20-year period. With these lakes, that’s normally not a huge deal, because a lot of this gas is trapped beneath the ice in the winter. And the winters last long enough for bacteria to convert the methane into a form that isn’t gaseous and can’t escape when everything thaws.

But as these icy seasons get shorter, there will be more chances for methane gas to enter the atmosphere — potentially a lot of it, depending on the place. If that happened, the global climate would get warmer, so more ice would melt, so more methane would escape… you get the idea. It’s called a positive feedback loop and they are usually bad.

And this all makes it even more important that we understand what’s happening in frozen lakes — not just for the joy of exploration and lightin’ big fires, but also that we can understand these effects and how to prepare for and prevent them. If you want to learn more about the big fields that go into climate science, you might want to check out one of Brilliant’s courses after this. They have courses on things like Scientific Thinking and Solar Energy to help you grow your math and science skills.

And they’re made by educators and lifelong learners from places like MIT, Caltech, and more. If you want to check them out, you can head over to Brilliant.org/SciShow. And if you’re ready to jump in, the first 200 people to sign up there will get 20% off their annual Premium subscription.

If you find a course you love, let us know! {♫Outro♫}.