On Thin Ice: Big Northern Lakes Are Being Rapidly Transformed
As temperatures rise, the world’s iconic northern lakes are undergoing major changes that include swiftly warming waters, diminished ice cover, and outbreaks of harmful algae. Now, a global consortium of scientists is trying to assess the toll.
For more than 25 million years, Lake Baikal has cut an immense arc from southern Siberia to the Mongolian border. The length of Florida and nearly the depth of the Grand Canyon, Baikal is the deepest, largest in volume, and most ancient freshwater lake in the world, holding one-fifth of the planet’s above-ground drinking supply. It’s a Noah’s Ark of biodiversity, home to myriad species found nowhere else on earth. It’s also changing fast, due to heat-trapping greenhouse gases that are increasingly disrupting the climate.
Baikal’s surface waters are warming at an accelerating pace, rising at least 2 degrees Celsius (3.6 Fahrenheit) over the past quarter century — twice as fast as global air temperatures, new research shows. The ice season, which typically covered the lake from January through May, has been shortened by nearly three weeks since the mid-1800s, and the ice has thinned nearly 5 inches since 1949. By the end of the century, scientists say that Baikal could be ice-free a month or more longer than today.
This rapidly changing climate threatens the lake’s unique, cold-adapted creatures, including the iconic nerpa — the world’s only true freshwater seal — whose fertility drops in warmer winters. Fishermen complain that the omul — a once-bountiful species of whitefish — has already grown scarce. Rising temperatures may also factor into some mysterious new problems plaguing the lake in the past few years. The brilliant green underwater forests of endemic Baikal sponges are dying, victims of an unknown pathogen. And dense algal mats choke wide swaths of bottom near shore.
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