In a strikingly visual demonstration of the effects of global warming, the Slims River in the Yukon area of Canada has almost disappeared overnight. Analysis of data collected by a team of scientists who documented the change shows that there is a 99.5% likelihood that this event was caused by post-industrial climate change due to human activities.
The Slims, which was previously around 3 metres deep and up to 150 metres wide, has been re-directed into the Kaskawulsh River by a period of intense glacier melting which caused an alternate channel to be carved into the ice and re-directed the river’s flow. This has resulted in a huge increase in water being carried to the Gulf of Alaska rather than into the Bering Sea. It has also left the Slims as a dried out dust bowl.
Although evidence of similar events has been detected in the distant past, this is the first instance of ‘river piracy’ to be documented in the modern era.
There have been knock-on effects for local ecosystems including Alsek River, which is part of a UNESCO World Heritage region and is now receiving significantly increased flow from the glacier. Although the area is sparsely populated and the impact on human settlements has so far been limited, the analysis points out that this kind of instant and massive restructuring of a river system could be devestating in an area where people rely on a watercourse.
Prof Lonnie Thompson, a paleoclimatologist at Ohio State University, said the observations highlight how incremental temperature increases can produce sudden and drastic environmental impacts. “There are definitely thresholds which, once passed in nature, everything abruptly changes,” he said.