Piracy on High Waters
Not Your Typical Swashbucklers
“Piracy” undoubtedly will prompt many to think of the eighteenth century swashbucklers that roamed the Mediterranean and Caribbean seas, pillaging and looting both coastal towns and merchant ships; the duplication and distribution of copyrighted material; or even identity theft. A recent phenomenon, however, shines the spotlight on an unseen piracy: river piracy.
River piracy, or the diversion of headwater from one stream or river to another, is an infrequent phenomenon; and when it does occur, such a process is ordinarily caused by erosion and tectonic shift and will take centuries, if not millennia, to complete. The piracy of the Slims River in Canada’s Yukon territory, however, startled scientists and geologists with its short completion time of a few months, a geological nanosecond .
For thousands of years, the Kaskawulsh Glacier (standing 8000 feet above sea level) in Canada’s Yukon territory has fed the Slims River and Kaskawulsh River with its meltwater. While the Slims River (which then flows into the Yukon River), carries the meltwater from the glacier west to the Bering Sea, the Kaskawulsh River (which flows into the Alsek River) carries the meltwater south into the Gulf of Alaska.
Scientists have been documenting the thinning and retreat of the Kaskawulsh Glacier for years, but beginning in 2016, scientists noted that the intense melting rate of the Kaskawulsh Glacier (which scientists attribute to global warming) was causing the redirection of meltwater from the Slims River to the Kaskawulsh. “We found that all of the water that was coming out from the front of the glacier, rather than it being split between two rivers, it was going into just one,” said James Best, geologist at the University of Illinois.
The Slims River, which was once measured as being 150 meters across its breadth, is now nearly gone. “The water was somewhat treacherous to approach, because you’re walking on these old river sediments that were really goopy and would suck you in. And day by day we could see the water level dropping” said Dan Shugar, assistant professor of geoscience at University of Washington, Tacoma. Whereas the Kaskawulsh and Slims Rivers had been comparable in size only two years before, flow measurements have shown that the Kaskawulsh River is now at least sixty to seventy times larger than the Slims.
Though the effects of the dramatic meltwater redirection are still unknown, many predict that the consequences will be catastrophic — after all, an entire river has disappeared. “If a river changes course so drastically that the drainage basin no longer reaches its original outlet, this change might eventually impact human and biological communities that have grown around the river’s original outlet,” said Rachel Headley, a geologist at the University of Wisconsin-Parkside. “While one remote glacial river changing its course in the Yukon might not seem like a particularly big deal, glacier melt is a source of water for many people, and the sediments and nutrients that glacier rivers carry can influence onshore and offshore ecological environments, as well as agriculture.”
However, the Slims River piracy may not be an isolated event, as the disappearance of the Slims may be the first of many river-related geomorphological phenomenon. Other similar events are likely to already be in progress, though Shugar argues that as the Kaskawulsh Glacier itself serves as a high point in its landscape and as a drainage divide for the meltwater, it is unlikely for other instances of river piracy to be as dramatic as that of the Slims River and thus such processes may remain undetected for the time being.
“We may be surprised by what climate change has in store for us — and some of the effects might be much more rapid than we are expecting,” says Shugar. This is the beginning of a new era; with our world changing so quickly, the future remains uncertain. One thing is for certain, though: the attention the environment deserves is long overdue.
