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Natural Rerouting

April 27th, 2017 in News by admin

DAN SHUGAR/UNIVERSITY OF WASHINGTON TACOMA

A river vanished in just four days after the glacier it flowed from retreated due to climate change.

The Slims River in Canada is the first in modern history to have disappeared at such a speed. Normally a river takes thousands of years to expire, as tectonic forces, natural damning or erosion reroute the water into a different path. But at the end of May 2016, the Kaskawulsh Glacier retreated so far that its meltwater was diverted into another river in an event described by researchers as “geologically instantaneous”.

Photograph shows the meltwater stream along the toe of the Kaskawulsh Glacier seen on the left that is diverting fresh water from one river to the other.

“Geologists have seen river piracy, but nobody to our knowledge has documented it happening in our lifetimes,” lead author Dan Shugar, a geoscientist at the University of Washington Tacoma, said 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.”

As a result of the event, glacial meltwater that for hundreds of years ran into the Bering Sea will now will flow into the Pacific.

The rerouting of the river has already taken its toll on both regional ecosystems, with disruptions to lake chemistry with variations in acidity, fish populations and the behaviour of wildlife such as moose migration and wolf behaviour.

jim-best

JIM BEST/UNIVERSITY OF ILLINOIS

Such changes of river channel highlight the power of climate change to redraw landscapes. In the UK such events supported the rerouting of rivers such as the River Trent which prior to the last ice age flowed from the mountains of North Wales eastwards to its outfall into the North Sea at The Wash. With the retreat of Welsh ice sheet and its meltwater this source dried up and water from the West Pennines replaced it.

The River Trent’s route changed further with the debris of melting ice blocking its exit towards the east and forcing its route northward to cut a new channel to the Estuary of the Humber.

All rivers when allowed to evolve naturally change and reroute themselves. The courses shaped by such events are brought about by natural processes: meanders that are cut through, floods cutting away land and washing away obstructions, these are the primeval results of erosion and shifting weather patterns. The speed of these changes today appear swifter than the eons of geological time that one might expect and major transformations to the landscape ‘do not happen’ today except if it is be blamed on global warming and climate change. The climate has always varied but it is the concern of humankind that the rapidity which is now accepted has been brought about by human action which needs to be curbed.

The slowing down of climate change is though hard to achieve due to nature: as mankind tries to control it in one direction natural reactions bite back in another way. Cutting air pollution seems harder to limit as most people are individually responsible for polluting the atmosphere on a day to day basis, many more than those able to directly pollute water. But if air is polluted water suffers. This is a major issue for all but to understand nature there needs to be a more holistic approach that anyone is fully appreciating today.

 

Author: admin

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