Nestled in the Alberta foothills of the Rocky Mountains lies a narrow lake that has been attracting attention for a rather unusual reason: its bubbles.

In summer, Abraham Lake boasts the same tropical blue hue of other glacial lakes in the region. But in winter, the lake’s surface is pockmarked with hundreds of frozen white bubbles that appear stacked beneath the surface.

The cause? Methane gas, which is excreted by bacteria feeding on dead animal and plant matter on the bottom of the lake. The gas bubbles freeze as they reach the colder water near the surface, forming columns as the ice thickens.

This doesn’t just happen at Abraham Lake; ancient methane is present in water bodies across the Arctic in the form of a solid compound called methane hydrate.

The phenomenon is particularly prevalent at Abraham Lake because it is not a natural lake. Created in 1972 by the damming of the North Saskatchewan River, the lake boasts an abundance of organic matter such as plants and grasses on its bottom that wouldn’t ordinarily be there — plenty of extra food for methane-creating organisms.

While the frozen bubbles are beautiful, the phenomenon has a dark side: methane is a greenhouse gas, and scientists worry a warming Arctic could cause unprecedented amounts of it to be released into the atmosphere, further accelerating climate change.

Check out photos of Abraham Lake from our Photo Club members: