Cities are first and foremost about water: No water, no city. And the consequences of urban water crises can be global.
The New York Times illustrates that effectively in this story about Mexico City:
It is a cycle made worse by climate change. More heat and drought mean more evaporation and yet more demand for water, adding pressure to tap distant reservoirs at staggering costs or further drain underground aquifers and hasten the city’s collapse. …
Always short of water, Mexico City keeps drilling deeper for more, weakening the ancient clay lake beds on which the Aztecs first built much of the city, causing it to crumble even further.
Colored areas show how quickly the ground sank from October 2014 to May 2015
Much is being written about climate change and the impact of rising seas on waterfront populations. But coasts are not the only places affected. Mexico City — high in the mountains, in the center of the country — is a glaring example. The world has a lot invested in crowded capitals like this one, with vast numbers of people, huge economies and the stability of a hemisphere at risk.
One study predicts that 10 percent of Mexicans ages 15 to 65 could eventually try to emigrate north as a result of rising temperatures, drought and floods, potentially scattering millions of people and heightening already extreme political tensions over immigration.
The effects of climate change are varied and opportunistic, but one thing is consistent: They are like sparks in the tinder. They expose cities’ biggest vulnerabilities, inflaming troubles that politicians and city planners often ignore or try to paper over. And they spread outward, defying borders.
Maybe the message is that sometimes cities just need to be left to die. Never a good location, the staggering population has made it that much worse. Start by establishing a new governmental capital on a greenfield site more logical.
The second message is that maybe we shouldn’t be encouraging such rampant urbanization around the globe. There’s a point where such metropolitan areas become unwieldy unsustainable and unworkable.
Can you clarify how “we” encourage rampant urbanization? Don’t successful cities grow because the offer opportunity and people want to move there?
Do you propose social engineering as your solution?
I hesitate to engage this discussion: hydraulic subsistence is not my expertise. I nevertheless have been a regular visitor to Mexico City since the sixties and lived in Centro Historico for nearly two years in the late nineties.
The last time I was there, about three years ago, an extensive re-paving program was underway in Centro so, clearly, there is confidence yet.
The current Mexico City was the Aztec Capitol Tenochtitlan, an island in Lake Texcoco: the Aztecs made of the city their capitol. It has always been subject to inundation and I doubt the current AGW hysteria can help.
A pendulum hangs inside the main tower of the Metropolitan Cathedral showing the progression of the angle of subsistence, at least, in that area of that magnificent structure. Which gives me cause to believe the city has known of the problem for a long time and seems confident, whatever the imminent danger, it is manageable.