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.
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.
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.