Researchers at the University of Washington have discovered the first recorded case of “river piracy,” according to a new study in the journal Nature Geoscience.
River piracy is a process that occurs when the water from one river gets taken over by another. Though the event pops up here and there in the geological record, it has never been noted in real time.
“Geologists have seen river piracy, but nobody to our knowledge has documented it happening in our lifetimes,” said lead author Dan Shugar, a geoscientist at the University of Washington, in a statement. “People had looked at the geological record — thousands or millions of years ago — not the 21st century, where it’s happening under our noses.”
The process occurred in northern Canada when a melting glacier caused the Slims river — which normally flows north — to become completely cut off from its water supply. That then made all of the water than normally feeds into it rush to the south-flowing Kaskawulsh river instead.
This strange occurrence came as a surprise to researchers, who first went to the area to see how the Slims river adjusts over the course of a year. When the team arrived to do observations they found a shallow lake where the river had once flowed, Popular Science reports.
To figure out the reason behind this phenomenon, the team traveled to the river’s source at the Kaskawulsh glacier. This revealed that, while the large sheet supplies many bodies of water in the area, it no longer feeds the Slims.
This example of river piracy is unique not only because it is occurring in modern times, but it happened as a result of the glacier’s position. The ice chunk sits directly between two drainage basins, which is why it managed to feed two rivers for such a long period of time. However, global warming has caused the glacier to steadily melt over the years.
Now that it is smaller, the ice takes up a much different place in the mountains. This caused the once-equal meltwater to now primarily flow to the Kaskawulsh river. As the glacier would need to advance to bring the Slims back — an unlikely event in the face of rising global temperatures — the river is unlikely to recover from this change. The Slims will now have much-reduced flows while the Kaskawulsh river will be much stronger.
This finding is important because it gives insight into the different ways climate change can affect our world. While most research is focused on the oceans, inland areas also can change. Shifts in climate can alter many different parts of such ecosystems, including lake chemistry, wildlife behavior, sediment transport, and fish populations.
“So far, a lot of the scientific work surrounding glaciers and climate change has been focused on sea-level rise,” added Shugar. “Our study shows there may be other underappreciated, unanticipated effects of glacial retreat.”