Canada's Saraswati: Massive river flowed into oblivion in just 4 days!

It takes decades, or centuries even, for rivers to merely change their course. But one river in Canada vanished into thin air — quite literally — in only four days last year, with climate experts blaming a rapidly melting glacier in the river's headwaters for the abrupt disappearance.

The Slims river was immense in scale and stretched to 150 m at its widest points. For hundreds of years, it carried melt water northwards from the Kaskawulsh glacier in the country's Yukon territory into the Kluane river, and then into the Yukon river towards the Bering Sea.

But in what is believed to be the world's first-ever case of 'river piracy' — which denotes the flow of one river being suddenly diverted into another — the drainage gradient of the Slims river was tipped in favour of a second river, redirecting the melt water towards the Gulf of Alaska, and causing the Slims river to do its disappearing act.

This, scientists say, is a worrying sign of how climate change could be changing the geography of the world.

They add that the Slims river only began flowing around the year 1700, when the so-called "Little Ice Age" caused the Kaskawulsh glacier to advance, and then divert most of its melt water from the Kaskawulsh River to the Slims Valley. So in a sense, the river was only ever just a temporary variance in the landscape — a 300-odd year hydrological whim.

Nonetheless, the continental-scale rearrangement is ringing alarm bells among climate scientists. "Nobody to our knowledge has documented it (river piracy) happening in our lifetimes," Dan Shugar, a geoscientist at the University of Washington Tacoma, was quoted as saying in the Guardian. "People had looked at the geological record, thousands or millions of years ago, but not the 21st century, where it's happening under our noses," he added.

The river's disappearance highlights how incremental temperature increases can produce sudden and drastic environmental impacts — how, in a geological instant, a local landscape can be redrawn. The journal Nature Geoscience, in fact, concludes definitively that this particular instance of river piracy was due to post-industrial climate change.

It raises concerns about villages, towns and cities that spring up around available water sources, since such disappearances could affect a huge number of people.

It also brings to memory the disappearance of the river Saraswati in India. But that was a long time ago, and the answers about that disappearance are still a subject of conjecture.