Cities in the Flood Zone

[Image: New Orleans after Hurricane Katrina; photographer unknown].

One of very many interesting points made by Jan Zalasiewicz in his new book The Earth After Us is that rising sea levels in an era of global climate change might actually – ironically – increase humanity’s long-term chances of urban fossilization.
“If we and our children are very unlucky over the next few decades,” he writes, “and the waters rise swiftly, then many of our cities may be as well preserved as Pompeii, as though in aspic.”
After all, he adds, “if the sea rises quickly enough, and there is not time for the waves to do their work, landscapes may be drowned entire. Only a few meters beneath sea level, and what was the land now lies below the destructive surf zone. A hundred meters below sea level, and even the most violent storm waves can scarcely be felt. So, let the sea flood in, with its level jumping by meters over centuries or decades – or perhaps even years – and there simply will not be time for this wave energy to erode the landscape.”

[Image: The aquatic aftermath of Hurricane Ike, photographed by Carlos Barria for Reuters; via The Big Picture].

Then, once everything’s underwater, the silting will begin. The planet’s submerged coastal and river-delta cities will thus be “covered with sand and mud,” entombed within the very landscapes upon which they once rested.

    This would immediately put these regions beyond the reach of erosion – except perhaps for a little localized scouring by strong tidal currents – and into the kingdom of sedimentation. Our drowned cities and farms, highways and farms, would begin to be covered with sand, silt, and mud, and take the first steps towards becoming geology. The process of fossilization will begin.

And then, like some gigantic ribcage from a species no one will fully comprehend, bits of New Orleans and Amsterdam and Hanoi will be unearthed amidst the mudstones of a future geography.
So might rapid climate change mean not the complete erasure of humanity’s material traces but, with fantastic irony, civilization’s geologically long-term preservation?

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