Bubbles of highly-flammable methane frozen in iced-over lakes are a strange yet stunning natural phenomenon – but can be dangerous if popped. They also harbor problems for the environment.
Appearing to hang in suspended animation below the surface of frozen lakes, methane bubbles are a curious sight.
But while they may look stunning, were you to "pop" one and hold a lit match over it, explosive consequences would follow – while mostly harmless, methane is an extremely-flammable gas and would ignite.
Frozen methane bubbles can be seen in many lakes around the world, with one of the best-known places being Lake Abraham in Alberta, Canada.
In winter, wind speeds can reach 48 kilometers per hour at Lake Abraham – combined with very low temperatures, it means the ice that forms on the surface of the lake is very clear, giving visitors a fantastic glimpse of the frozen bubbles below. So how are they formed?
Frozen methane bubbles create a layered effect as they became trapped in the ice while rising to the surface
Methane bubbles are formed in water when dead organic material such as creatures or leaves sink to the bottom of the lake, which are then decomposed by bacteria. The bacteria then produce methane, which forms bubbles that rise to the surface.
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In summer, the bubbles simply pop when they reach the surface and enter the atmosphere. But in winter when the lake is frozen, the bubbles are trapped on their way to the surface.
But as beautiful as they may be, the frozen methane bubbles portend troubles ahead for the environment: as temperatures rise around the globe, more permafrost is melting – letting frozen organic matter thaw and providing more food for bacteria.
That means more methane – a powerful greenhouse gas around 25 times more effective at trapping heat than carbon dioxide - being released into the atmosphere, triggering rising levels of global warming along with it.
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