Year 4, Month 5, Day 25: Castles Made Of Sand

The Ottowa Citizen tells its readers that the ground is shifting beneath their feet:

OTTAWA — We learn from Saturday’s paper that carbon dioxide, the main greenhouse gas, is at its highest concentration in the atmosphere in three million years.

Over shouts of “We’re No. 1!”, it might be opportune to mention an unexplored consequence of climate change: our houses are cracking up.

Ottawa is built, with some exceptions, on a vast stretch of what the experts call “sensitive clay soil”, usually referred locally as leda, the old basin of the Champlain Sea.

During a prolonged drought in an urban area, here is the shorthand version of what happens: the band of clay dries out and shrinks, thirsty trees go deeper and further looking for water, buried voids begin to form, the footings of houses begin to slip and sag, and the hapless homeowner arrives home one day asking: “That’s funny, wonder why the front door is sticking?”

Here is a more scientific description from Canada Mortgage and Housing Corp.

“Sensitive clays have a higher proportion of water among their small particles. These tiny plate-like particles are arranged like a house of cards, holding each other up when the spaces between them are filled with water.

“When there is a severe loss of water, they collapse, leading to a reduction of soil volume and soil shrinkage.”

Everything’s an analogy these days. May 13:

As the clay upon which they’re constructed dries and shrinks, corresponding fault lines appear in Ottowa’s buildings themselves, as walls and foundations attempt to compensate for deep fundamental transformations happening under the surface. On a local level, this may be just a story about houses and soil — but the settling and cracking of ground and concrete is a potent metaphor for the profound and potentially devastating changes now under way everywhere around the world.

The grand edifice of human civilization was made possible by a stable and benign climate which permitted agriculture to flourish, helping us move from a simple struggle for daily survival to the grand and inspiring sweep of our species’ achievements. This complex and interdependent society rests upon countless environmental factors which we have long taken for granted, but which are now threatened by global climate change. If we do not act promptly and responsibly to address the crisis, we will find that the Earth has shifted beneath our feet, leaving our mansion unable to stand.

Warren Senders


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