Methane bubbles, beautiful and dangerous
Take a look at this beautiful photograph:
Photo: Corey Tran / Unsplash
It was taken at Lake Abraham in Canada. The lake is a tourist attraction famous for the gas bubbles that can be seen frozen inside crystal clear ice in the winter. Today, we will tell you where these bubbles come from, and how they are related to shipwrecks and the end of the world.
What are they?
The bubbles are made up of methane, produced by archaea, primitive single-celled bacteria. While humans inhale oxygen and exhale carbon dioxide, archaea can inhale hydrogen, carbon dioxide or methanol, and exhale methane. Initially, the methane produced by archaea is dissolved in water, like sugar in tea. But under certain conditions, it can become gaseous.
The coloured plaque on the rocks is archaea. They are famous for their ability to live in extreme environments such as salt lakes, underwater volcanoes and geysers. Photo: Amy Hamerly / Unsplash
Solid gas
Methane, which is exhaled by archaea, can be found contained within the entire water column. But at high pressure (i.e. at great depths) and at low temperature, it can «stick» to water at a molecular level, and form a new substance: methane hydrate. The texture of methane hydrate resembles dense snow. However, there is a «small» difference: methane hydrate burns if it is set on fire.
Methane hydrate usually forms at the bottom of oceans and northern lakes, and can sit there for thousands of years. But if the conditions change, (e.g. the water gets warmer), the hydrate can warm and break up to form methane gas bubbles, which then rise to the surface.
The fate of the bubbles
A bubble of methane rising from the bottom can safely rise to the surface, and end up in the atmosphere. But if the lake is covered with ice, it will crash into the ice crust and stay underneath. If tit stays cold enough, the ice layer grows and gradually forms around the bubble. This is how the bubbles get trapped in the ice one by one. As they freeze, stuck inside the ice, they end up flat rather than round.
People who find such bubbles can not only take beautiful pictures of them, but can also experiment with burning bubbles.
Methane «pancakes» at Lake Abraham. It’s far from the only lake with methane bubbles, but it’s definitely the most famous. Photo: David Wirzba / Unsplash
The fate of the planet
And there are several scary stories associated with methane bubbles. The most pressing one today is their impact on climate change. We already know that one of the causes of methane hydrate collapse is rising water temperatures. But we also realize that methane is a greenhouse gas, and its effect on rising temperatures is 30 times greater than carbon dioxide.
These two features can lead to an avalanche-like effect of warming in the atmosphere: water heats up, methane hydrate breaks down, methane gas ends up in the atmosphere, the air gets warmer due to the greenhouse effect, water heats up in the air. Roughly speaking, once the lake is heated up, it will continue to heat up on its own.
Some scientists believe that with global warming, at some point, methane will be released at such an enormous rate that an ecological catastrophe will occur. Up to and including the threat of the end of the world: «the seas will boil, random lightning will ignite the atmosphere and destroy all life, and the sun will disappear behind black smoke.»
Of course, this is an unlikely scenario. But the role of methane hydrate in climate change may indeed be much greater than we expect.
The mystery of the Bermuda Triangle
But methane has a knack for scaremongering on a smaller scale, too. For example, methane gas hydrate is associated with one of the most popular scientific explanations for the phenomena of the Bermuda Triangle.
Abnormal zone... Abnormally beautiful. Photo: Ivaya Valcheva / Unsplash
But this theory has a few problems:
- No one has ever seen bubbles of a size or number large enough (according to modeling data) to sink a ship.
- Methane hydrate in the Bermuda Triangle is reported to be in a stable state, and has not collapsed in the last 15,000 years.
- There are methane hydrate deposits all over the world—the Bermuda Triangle is not unique in this respect.
By the way, methane can also lead to airplane crashes. Since it is less dense than air, when an airplane hits a methane cloud, an «air pocket» effect occurs. But, as we have already realized, all of this works only in theory. There are no proven cases of methane being at fault right now.
Methane bubbles are a perfect illustration of how little we know about nature. Some see them as just a beautiful frosting on lakes, while others see them as the culprits behind missing ships and a possible cause of humanity’s demise. Science should separate facts from rumors, but for now, the data is clearly not strong enough to fully support these radical conclusions. So, many more interesting discoveries are waiting for us in the future!
Text: Eugenio Monti, a meteorologist and a climatologist
Cover photo: Alex Pugliese / Unsplash
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