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. Graphics by Derek Watkins and Jeremy White.
Design by Matt Ruby and Rumsey Taylor. 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.
And they spread outward, defying borders. Around the world, extreme weather and water scarcity are accelerating repression, regional conflicts and violence. And nowhere does this apply more obviously than in cities. By that time, according to another study, there may be more than million climate refugees on the move.
For many cities around the world, adapting to climate change is a route to long-term prosperity. But adaptation can also be costly and slow. It can run counter to the rhythms of political campaigns and headlong into powerful, entrenched interests, confounding business as usual. This is, in effect, what happened in New Orleans, which ignored countless warning signs, destroyed natural protections, gave developers a free pass and failed to reinforce levees before Hurricane Katrina left much of the city in ruins.
It is certainly not what residents in Mexico City talk about every day. But it is like an approaching storm, straining an already precarious social fabric and threatening to push a great city toward a breaking point. Sign up to receive our in-depth journalism about climate change around the world. But over the decades, the whole neighborhood around the monument sank, like a receding ocean at low tide, gradually marooning the Angel.
Fourteen large steps eventually had to be added to the base so that the monument still connected to the street. Buildings here can resemble Cubist drawings, with slanting windows, wavy cornices and doors that no longer align with their frames. Pedestrians trudge up hills where the once flat lake bed has given way. Loreta Castro Reguera is a young, Harvard-trained architect who has made a specialty of the sinking ground in Mexico City, a phenomenon known as subsidence. The whole city occupies what was once a network of lakes. Over time, they expanded the city with landfill and planted crops on floating gardens called chinampas, plots of arable soil created from wattle and sediment.
The lakes provided the Aztecs with a line of defense, the chinampas with sustenance. The idea: Live with nature. Then the conquering Spaniards waged war against water, determined to subdue it. The Aztec system was foreign to them. They replaced the dikes and canals with streets and squares.
They drained the lakes and cleared forestland, suffering flood after flood, including one that drowned the city for five straight years. Castro said.
Mexico City, Parched and Sinking, Faces a Water Crisis
We now have 21 million. Mexico City today is an agglomeration of neighborhoods that are really many big cities cheek by jowl. During the last century, millions of migrants poured in from the countryside to find jobs. Highways and cars choke the atmosphere with heat-inducing carbon dioxide — and development has wiped out nearly every remaining trace of the original lakes, taxing the underground aquifers and forcing what was once a water-rich valley to import billions of gallons from far away.
The system of getting the water from there to here is a miracle of modern hydroengineering. But it is also a crazy feat, in part a consequence of the fact that the city, with a legacy of struggling government, has no large-scale operation for recycling wastewater or collecting rainwater, forcing it to expel a staggering billion gallons of both via crippled sewers like the Grand Canal. Mexico City now imports as much as 40 percent of its water from remote sources — then squanders more than 40 percent of what runs through its 8, miles of pipes because of leaks and pilfering.
For some residents, water comes only once a week, or once every several weeks, and that may mean just an hour of yellow muck dripping from the faucet. Those people have to hire trucks to deliver drinking water, at costs sometimes exponentially higher than wealthy residents pay in better-served neighborhoods. The problem is not simply that the aquifers are being depleted.
Mexico City rests on a mix of clay lake beds and volcanic soil. Areas like downtown sit on clay. Other districts were built on volcanic fields.elezojehiwih.ga
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Volcanic soil absorbs water and delivers it to the aquifers. Picture a bucket filled with marbles.
You can pour water into the bucket, and the marbles will hardly move. For centuries, before the population exploded, volcanic soil guaranteed that the city had water underground. This is part of the sprawl problem. Now, picture layered sheets of plastic.
On a molecular level, clay acts sort of like that. Instead, water settles between the sheets. When the water is drained, the sheets can collapse and crack. Aguirre said. But because the city is built on a mix of clay and volcanic soil, it sinks unevenly, causing dramatic and deadly fissures. Fifteen thousand houses in the area, he said, had been damaged by sinking ground. Deep below the historic center, water extracted from aquifers now can end up just beyond the city limits, in Ecatepec, at one of the largest pumping stations along the Grand Canal.
The pump, completed in , was built to move 11, gallons per second — essentially water that now needs to be lifted up from where the canal has collapsed, just so that it can continue on its way. According to Mr. Salgado, the Grand Canal today is working at only 30 percent of capacity because of subsidence. Parts of the canal around Ecatepec have sunk an additional six feet just since the plant was built, he said.
He showed me around one morning. The canal is wide open, a stinking river of sewage belching methane and sulfuric acid. Apartment blocks, incongruously painted cheerful Crayola colors, hug the bank. Salgado asked if I wanted a tour of the filters.
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The district of Tlalpan is on the opposite side of Mexico City. She has the slightly impatient, defensive mien of someone wrestling with an impossible mission. Heat waves mean health crises and rising costs for health care in a city where air-conditioning is not commonplace in poor neighborhoods. You can plug leaks in your home insulation to save power, install a smart thermostat, switch to more efficient light bulbs, turn off the lights in any room where you are not using them, drive fewer miles by consolidating trips or taking public transit, waste less food and eat less meat.
Perhaps the biggest single thing individuals can do on their own is to take fewer airplane trips ; just one or two fewer plane rides per year can save as much in emissions as all the other actions combined. If you want to be at the cutting edge, you can look at buying an electric or hybrid car, putting solar panels on your roof, or both. If you want to offset your emissions, you can buy certificates, with the money going to projects that protect forests, capture greenhouse gases and so forth.
You can also buy offset certificates in a private marketplace, from companies such as TerraPass ; some people even give these as holiday gifts. In states that allow you to choose your own electricity supplier, you can often elect to buy green electricity; you pay slightly more, and the money goes into a fund that helps finance projects like wind farms. Leading companies are also starting to demand clean energy for their operations.
You can pay attention to company policies, patronize the leaders, and let the others know you expect them to do better. In the end, though, experts do not believe the needed transformation in the energy system can happen without strong state and national policies. So speaking up and exercising your rights as a citizen matters as much as anything else you can do. In the best case that scientists can imagine, several things happen: Earth turns out to be less sensitive to greenhouse gases than currently believed; plants and animals manage to adapt to the changes that have already become inevitable; human society develops much greater political will to bring emissions under control; and major technological breakthroughs occur that help society to limit emissions and to adjust to climate change.
Some technological breakthroughs are already making cleaner energy more attractive. In the United States, for instance, coal has been losing out to natural gas as a power source, as new drilling technology has made gas more abundant and cheaper; for a given amount of power, gas cuts emissions in half.
In addition, the cost of wind and solar power has declined so much that they are now the cheapest power source in a few places, even without subsidies. Unfortunately, scientists and energy experts say the odds of all these things breaking our way are not very high. The Earth could just as easily turn out to be more sensitive to greenhouse gases as less.