There are few things that can change the course of a river suddenly. The New Madrid earthquakes in 1811-1812 briefly reversed the course of the Mississippi by suddenly shoving millions of tons of water in northward, but that was temporary. Normally, (unless like in Chicago you do it intentionally) rivers change directions or reroute their course very slowly, through generations of erosion as it pokes and prods and tries to find the easiest way to flow, a grinding process that eventually levels everything in its path, though never on the mere scale of a human lifetime.
Thanks to climate change, that might not always be the case. Times?
In the blink of a geological eye, climate change has helped reverse the flow of water melting from a glacier in Canada’s Yukon, a hijacking that scientists call “river piracy.”
This engaging term refers to one river capturing and diverting the flow of another. It occurred last spring at the Kaskawulsh Glacier, one of Canada’s largest, with a suddenness that startled scientists.
A process that would ordinarily take thousands of years — or more — happened in just a few months in 2016.
Much of the meltwater from the glacier normally flows to the north into the Bering Sea via the Slims and Yukon Rivers. A rapidly retreating and thinning glacier — accelerated by global warming — caused the water to redirect to the south, and into the Pacific Ocean.
Last year’s unusually warm spring produced melting waters that cut a canyon through the ice, diverting more water into the Alsek River, which flows to the south and on into Pacific, robbing the headwaters to the north.
Think about that. If you lived there (or, I guess, if you are a tremendous liar), you could say “I remember the days when these waters flowed north, onward to the Bering Sea”, and you’d be talking about last summer.
Now, to be fair, this was a perfect confluence of conditions: the way the land was shaped there didn’t have to be too much melt and erosion for the higher ground to make its way to the lower; the channels cut my newly melted water didn’t have far to go. We’re not going to wake up one day and see that the Ohio is charging back toward Pittsburgh. But it is still a stark and terrifying reminder that climate change isn’t something happening in the distant future. It is happening now, and it is really unpredictable.
In essence, we’ve decided as a species to enter a vast generational experiment where we see what happens when we accelerate natural processes and introduce unnatural ones. The earth heats and cools, glaciers advance and melt, rivers change their courses. These things happen on unimaginable time spans. They don’t happen over the course of a century, or the life of a summer. But, thanks to our desire to turn nature into capital, that’s what’s happening.
We don’t know how it will turn out. Things will happen that we can barely even guess. But it seems short-sighted to say it won’t be enormous.
I’ll leave this with an example of what retreating glaciers mean. We all know that the glaciers carved out the Great Lakes and completely wiped out the landscape that came before them. And we know it was cold as hell. But I don’t think it is generally understood how much their immensity impacted geology, and not just topography.
They pressed down on the earth’s surface, slowly impacting it under their enormity. And as they retreated, the surface slowly started to rebound. This is a process that, tens of thousands of years later, is still happening. The impact of this can be felt right around here, in Chicago. When the glaciers first retreated, and the lakes took their present form, the ground was low enough that Michigan (and Lake Chicago before it) flowed southwards, toward the Mississippi Basin. But as the land rebounded, and glaciers cut more channels, eventually the whole Lakes basin made its way to the ocean.
Until, of course, the city of Chicago, disgusted with and sickened by the filth of its residents, reversed the course of the Chicago, turning southern Lake Michigan into an extension of the Mississippi Basin. That happened in a geologic instant. The reversal of the Yukon rivers was even quicker. It was instant.
Our impact on the planet might mimic the planet’s own cycles, as somewhat more sophisticated climate deniers claim, but that’s wildly misleading. It’s a gruesome imitation, at high-speed, a janky cassette player that suddenly turns your music into a screeching cacophony, with little regard for the consequences. It’s like jumping off the Empire State Building and saying you’re imitating the gentle swaying of a leaf on the wind. Same general direction maybe, and with the same end point, but brother, you’re fucked.
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