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California’s deadliest, most destructive fire in history leveled a city of 26,000 residents within a matter of hours. “Completely destroyed,” read the headlines. “Obliterated.” “Paradise lost.”

After a year punctuated by increasingly alarming climate reports, as well as some of the most devastating disasters for many U.S. cities, it’s been difficult to grasp the severity of what seems to be happening—and the fact that it seems to be happening faster and more frequently than anyone thought possible.

In November 2018, the Camp Fire burned 95 percent of the structures in the city of Paradise, killing 86 people.

But it was only a few weeks before the Camp Fire that a similar set of phrases were used to describe Mexico Beach, Florida, after one of the strongest hurricanes in U.S. history made landfall, killing 45 people: “It’s all gone,” “nothing left.”

No human lives were at risk, but seeing an 11-acre Hawaiian island vanish after a rare, powerful storm swept over the state elicited the same type of responses: “No one expected East Island to disappear this quickly.”

It’s clear now what the accelerated timeline of climate change really means is a swift, steady decline in the number of places where we will be able to make our homes, visit for pleasure, and, eventually, survive.

Environmentalist Bill McKibben described it this way in the New Yorker: “The planet’s diameter will remain eight thousand miles, and its surface will still cover two hundred million square miles,” he writes. “But the earth, for humans, has begun to shrink, under our feet and in our minds.”

Climate change has started taking our cities away, much sooner and more dramatically than we expected. Looking forward to 2019, it’s no longer a decision about where we want to live. The question is, how much longer will we be able to live there?

When the Intergovernmental Panel on Climate Change issued its grim, game-changing report last October, it noted that the most devastating impacts of climate change were decades, not generations, away. Just one month later, the National Climate Assessment, a report by 300 experts and 13 U.S. government agencies, snapped the looming threat into sharp, localized focus for Americans—with explicit directions for the future.

Region by region, the National Climate Assessment breaks down where the U.S. population will be exposed to the most dangerous climate impacts like storm surges, extreme flooding, or wildfire. The report then warns that U.S. cities will face dire consequences if leaders do not adapt to these risks.

Most importantly, cities must make these changes before—not after—disaster strikes.

“Communities have been less focused on reducing exposure through actions such as land-use change (preventing building in high-risk locations) and retreat,” reads the report. “Furthermore, many communities’ adaptation actions arise and are funded in the context of recovery after an event, rather than taken proactively.”

While there is now a heightened sense of urgency to reduce emissions—one year later, over 455 U.S. cities have joined the Climate Mayors—not enough of those mayors are looking at dramatically remaking their cities to address the coming crisis.

If these mayors agree that climate change threatens our cities, then they must confront the fact that some cities, their cities, must be relocated to confront climate change—or climate change will relocate them first.

The U.S.’s first climate refugees, from Isle de Jean Charles, Louisiana, and Shishmaref, Alaska, didn’t wait for a specific disaster to erase them—they’re slowly and purposefully abandoning their homes before they are erased from the map.

This is the way more cities need to be thinking. Over the next few decades, U.S. migration patterns will be almost exclusively determined by people who make an organized retreat from a known threat, but also people who are made homeless by a deadly disaster, and people who can’t continue to make a living in a devastated city.

Or a combination of all three. In addition to the almost 3,000 Americans killed in Puerto Rico after Hurricane Maria due to the complete breakdown of basic services, least 135,000 people fled the island and haven’t returned.

In the future, those who can afford to will escape Phoenix’s extreme heat or South Beach’s chronic flooding. They’ll engage in conversations about where to move to avoid climate change’s worst effects. (Chicago, probably.) Others will stay in cities for as long as they can and build second homes as a safety net.

There’s a scene in the 2018 National Geographic documentary Paris to Pittsburgh, which chronicles how cities are taking action after the U.S. withdrew from the Paris accord, where University of Miami geologist Harold Wanless is sitting on a boat in the Everglades with Chris Castro, director of sustainability for the city of Orlando.

Florida’s fresh water source is rapidly experiencing saltwater intrusion due to sea level rise, and Wanless estimates that within a century, Miami will be unlivable.

“So in reality, in South Florida, we’re just going to be leaving,” says Wanless to Castro. “We don’t have the problem. You, up in Orlando, you better set aside your groundwater resources and you better plan for us. You really better plan, because we are coming... we will be coming.”

Among the more stunning stories we reported here at Curbed in 2018 were those that described the shrinking real estate map. More than 1 in 10 homes just in California are located in the highest-risk zones for wildfire. Over 300,000 homes and businesses across the country could be permanently underwater by 2045.

Yet there’s been no concerted effort by the federal, state, or local governments to stop people from building more homes in these places. And there are even fewer efforts to work with the neighboring cities that will need to absorb these new residents in the face of catastrophic losses.

Mayors say they’re committed to climate action. Yet if the climate disaster happens to them—when it happens to them—mayors instead claim publicly that they will rebuild, ignoring the conversations about how they shouldn’t.

The city of Malibu, for example, is one of the 455 cities that joined the Climate Mayors, committing to “demonstrate leadership on climate change through meaningful action.”

But in December, Malibu mayor Rick Mullen, who is also a full-time captain with the Los Angeles County Fire Department, said that his priority after the Woolsey Fire was to rebuild the 400 homes destroyed as fast as possible—not to make the community more fire-resistant or climate-resilient.

“It could be this is a wonderful time to say we’ve got some serious issues,” he told Curbed. “I’m more interested in getting people moving forward.”

It’s no longer a decision about where we want to live. The question is, how much longer will we be able to live there?

As Democrats regained control of the House of Representatives during the midterm elections, many incoming congressional leaders sworn in this month made a Green New Deal a central part of their platforms.

A Green New Deal would put Americans to work running the industries that can dramatically lower emissions and building the infrastructure to mitigate the now-unavoidable impacts. Adaptation, and how cities could work together to prepare for the inevitable population shifts on the horizon, could be a central part of this conversation.

After the past year, there’s no doubt that cities working together can have an outsize impact on climate action. In fact, carbon emissions have already peaked in 27 cities worldwide, no small feat when 2018 ended with the news that global emissions—including U.S. emissions—actually increased.

Committing to climate goals has become a powerful symbol of unity. But the tougher decisions are ahead of us now. As a society we must focus on reshaping our cities quickly—so Americans will be able to coexist with the consequences.