Like most glaciers worldwide, Kaskawulsh Glacier in the Kluane National Park and Reserve of southwestern Yukon Territory, Canada, has retreated over the past several decades. An article in the journal Nature Geoscience confirms that this glacier’s retreat caused a rare instance of “river piracy”—the diversion of the headwaters of one stream into another one.

The end of Kaskawulsh Glacier lies at a drainage divide. Before spring 2016, the majority of the glacier’s meltwater flowed north by way of the Slims River into Kluane Lake, and from there into the Yukon River and to the Bering Sea. As the 2016 Landsat 8 image shows, the majority of the meltwater now flows toward the east into the Kaskawulsh River, which makes its way to the Alsek River and to the Pacific Ocean.

The meltwater from the glacier previously had brought a large supply of sediment to Kluane Lake. With this sediment supply ending, the ecosystem of the lake could change. On the other hand, increased sediment and a higher volume of water now flowing into the Kaskawulsh River may increase its bank erosion. For both rivers, the sediment changes, varied timing of flows from the glacier, and amount of water in the channels could affect fish populations and habitats downstream.

The researchers point out that this change is likely long-term, so downstream ecosystems could be permanently altered. Landsat can help study these changes to the habitats of the region.