Anja Rutishauser

Canadian ice cap conceals supersalty lakes

At least two large, supersalty lakes lie deep beneath an ice cap in far northeastern Canada, a new radar survey shows. The survey traced the mountainous terrain underlying the Devon Ice Cap (pictured), a frozen mass almost the size of Connecticut. But in a couple of places, the researchers also saw strong, mirrorlike reflections.

The radar was apparently bouncing off the surfaces of subglacial lakes hundreds of meters down, one covering about 5 square kilometers and the other a little more than 8 square kilometers, the researchers report today in Science Advances.

How does the water remain liquid at temperatures estimated at –14°C and –15°C, well below freezing? The researchers credit a fluke of geology: The lakes apparently sit atop thick salt deposits laid down hundreds of millions of years ago, which act like road salt to keep the water liquid. The water must be at least four or five times as salty as the ocean, the researchers estimate. That’s not too salty to host microbial life, as a similarly briny subglacial lake in Antarctica proves. But if these Canadian lakes host an ecosystem, it has likely been isolated since the beginning of the last ice age about 120,000 years ago.