IN THE LATE 1970S, UC Berkeley geologist Walter Alvarez stopped in Denmark on his way home from a research trip to Italy. Alvarez was hunting for evidence to support his wild and still unproven idea that a planet-wide disaster, such as a giant meteor strike, had killed off the dinosaurs 66 million years ago. The idea that the dinosaurs (and basically all other life on Earth that was larger than a raccoon) could have been killed off by a cataclysmic event went against evolutionary dogma, which held that extinction was a long, slow process, just like evolution itself.
Alvarez, prompted by his famous father, Nobel Prize–winning physicist Luis Alvarez, had other ideas. In Denmark, Walter Alvarez and a colleague drove out from Copenhagen to Stevns Klint (klint is Danish for “cliff”), a well-known geological site on the Baltic Sea. The rough white cliffs there are one of the few places in the world where you can see the dinosaurs’ last days written in well-defined layers of limestone. About halfway up the cliffs a thin, dark line of clay is sandwiched between the limestone layers. “It was clear right away that something unpleasant had happened to the Danish sea bottom where the clay was deposited,” Alvarez later wrote. The limestone below the clay line was full of fossils, representing the teeming life of the sea. But the clay bed itself was black, smelled sulfurous, and contained no fossils but fish bones. “During the time interval represented in the clay, the sea bottom had turned into a lifeless, stagnant, oxygen-starved graveyard, where dead fish slowly rotted,” Alvarez observed. Alvarez took some samples of the fish clay and discovered that it contained iridium, a rare metal that is scarce on Earth but common in meteors. It was a key piece of evidence in one of the most dramatic scientific discoveries of our time. Today, even third graders know about the meteor that killed off the dinosaurs.
I was lucky enough to spend several weeks in Denmark while I was working on this book, mostly in Copenhagen, a city that prides itself on being one of the greenest in the world. There are bikes everywhere, and about 40 percent of the nation’s electricity comes from renewables (the Danish Energy Agency says the grid will be 100 percent renewables by 2035). I met with Lykke Leonardsen, a climate advisor for the city, who told me about some of the measures the city is taking to help drain its streets after increasingly intense rainfalls, such as building “water squares” similar to what I’d seen in the Netherlands. To protect the city from sea-level rise, city planners are already considering a barrier across each end of the main canal, closing it off from the Øresund, the strait that separates Denmark from Sweden and connects the city to the North Sea and the Baltic. In fact, Denmark is more likely to have problems caused by the flood of climate refugees from Bangladesh or Nigeria than by a flood of water from the Baltic Sea. The question of how to absorb refugees from the Syrian war is already tilting Danish politics to the right, and it’s hard to see how waves of climate refugees won’t accelerate that.
From Copenhagen, it’s about an hour and a half’s drive to Stevns Klint. Of course, given the subject of this book, I had to go see it. The highway took me out through the suburbs, then into a landscape dotted with well-kept farmhouses, some with thatched roofs. I parked my rental car at the top of a bluff, near an eleventh-century church overlooking the Baltic. A few years ago, as the cliff eroded, the back of the church tumbled into the sea. The rest of the church now hangs there precipitously, awaiting the same fate.
A long flight of metal stairs stretched down to the beach. It was like a staircase into Jurassic Park. One hundred million years ago, when the base of these cliffs was the bottom of the ocean, the world was a very different place: Europe was much closer to America, the seas were three hundred feet higher than they are today, and, of course, dinosaurs roamed the Earth.
I wandered along the curved shore, close to the chalky cliffs, looking for the fish clay. It wasn’t easy to spot. But I eventually found it—a thin, broken black layer, like a line of Magic Marker, about forty feet up. It was hard to believe that this was the last and best evidence of one of the most traumatic events we know of on Earth. The meteor that crashed into what is now the Yucatán peninsula in Mexico was the size of Manhattan, and when it hit the Earth, it released the energy of 100 million megatons of TNT. The fire incinerated everything within a thousand miles. Droplets of hot sulfuric acid and dust blocked out the sun. Then it became cold and dark for thousands of years.
It was sunny and mild when I walked on the beach, with a crisp breeze blowing off the Baltic. Flint pebbles rolled under my feet. If you were a dinosaur, I thought, this line of fish clay represented some very bad news. Dinosaurs dominated the Earth for millions of years, but they did not have the traits needed to adapt to a fast-changing world. Long before, changes in the climate, driven by volcanic eruptions, had probably stressed many species and made them vulnerable. The meteor finished them off. But it’s also true that for you and me and everyone we know, that meteor strike was a very fortunate event. It was an evolutionary reset, one that allowed mammals to thrive. It is very unlikely that we humans would have appeared and built a city like Miami, much less have submerged it by burning fuels made from dinosaur bones and other fossilized life, if the meteor had not killed off the planet’s reigning predators.
Of course, the dinosaurs did not have computer models to help them understand the likelihood of a meteor strike in their future. We humans think we’re much smarter and more adaptable than dinosaurs, and that because we have lots of sophisticated tools and big ideas about the past, present, and future, we can ride out whatever comes our way. That assumption may soon be put to the test.
If we want to minimize the impact of sea-level rise in the next century, here’s how we do it: stop burning fossil fuels and move to higher ground. We wouldn’t even have to stop burning fossil fuels tomorrow—if we did it by 2050, that would be good enough. It wouldn’t entirely halt sea-level rise, but it would avoid the worst of it. Instead of six, seven, eight feet, or more by the end of the century, we might get two or three. We would still need to retreat from the low-lying coastlines, but instead of a stampede, it could be a leisurely stroll.
Unfortunately, it’s hard to muster much faith that we will dramatically reduce CO2 emissions anytime soon—much less cut them to zero by 2050. If that’s the case, then planning for a world of rapidly rising seas will be much more difficult.
During my reporting for this book, I encountered a lot of thoughtful civic leaders and politicians who are thinking hard about how to reimagine the future in a world of fast-rising seas. In Norfolk, Virginia, city officials have collaborated with the US Navy and university researchers to come up with a comprehensive development plan for the year 2100 to help identify which neighborhoods are most at risk. The Southeast Florida Regional Climate Change Compact, which includes representatives of four counties in the region (including Miami-Dade), has pushed local and state officials to rethink zoning laws and cut bureaucratic impediments that delay aggressive measures to combat rising seas; the State of Louisiana released an ambitious and hugely expensive master plan to save its sinking coastline; in the UK, the government has encouraged a gentle retreat from the coasts through a “managed realignment” that encourages marshes and other coastal habitats to migrate inland, creating a natural buffer against the rising seas. In the Netherlands, they’ve been thinking about how to battle the sea for a thousand years and are now exporting that knowledge around the world. Wherever there is a city at risk of flooding, you’ll likely find a Dutch engineer offering—or, just as often, selling—a solution.
These initiatives are all important, but they are just the preliminary sketches of the changes that need to be made in the decades ahead. The sheer economic chaos that looms for some coastal regions is hard to grasp, much less anticipate and prepare for. Nor do these initiatives begin to grapple with the political and psychological trauma of losing entire cities and coastlines, as well as the hopes and dreams that adhere to those cities and coastlines. As our planet changes, so will we.
Maybe in our increasingly rich and human-engineered world, losing some beaches and cities won’t matter so much. If the real Venice goes under, you can always visit the fake Venice in Las Vegas. And maybe Miami Beach will be nearly as awesome in virtual reality. (Then again, maybe not.) Perhaps the best we can hope for is that living in a world of quickly rising seas will turn out to be a planetary-scale experiment in creative destruction, one that forces us to abandon a lot of stupid infrastructure and stupid ideas about how to live with water—and how to live with each other—and replace them with something smarter, more durable, more flexible. After all, other than cockroaches, humans are probably the most adaptable creatures on the planet. “To be honest, I’m looking forward to it,” one Miami developer told me. “The only way we can survive this is to knock down a lot of old buildings and build new buildings that are higher, better, stronger. I joke with my wife, ‘Hey, let’s go buy a Hummer! Let’s speed this thing up a little bit! How long do we have to wait?’”
The inundation of a modern coastal city is not something humans have ever witnessed before. We’ve seen floods and storms, but this will be nothing like what’s to come. Even if it happens fast, it will seem to happen slowly. People are likely to notice in the same way they notice aging: Oh, look how tall my kids are all of a sudden!
In a similar way, people will notice higher tides that roll in more and more frequently. Water will pool longer in streets and parking lots. Trees will turn brown and die as they suck up salt water. Then a storm will hit, and it will push an astonishing amount of water into the city. Some people will move to new, higher buildings. Others will simply move to higher ground. Roads will be raised. Solar panels will bloom on rooftops. Abandoned houses will linger like ghosts, filling with feral cats and other refugees looking for their own high ground. Water will continue to creep in. It will have a metallic sheen and will smell bad. Kids will get strange rashes and fevers. More people will leave. Seawalls will crumble. In a few decades, low-lying neighborhoods will be knee-deep. Wooden houses will collapse into a sea of soda bottles, laundry detergent jugs, and plastic toothbrushes. Human bones, floated out of caskets, will be a common sight. Treasure hunters will kayak in, using small robotic submersibles to search for coins and jewelry. Modern office buildings and condo towers will lean as the salt water corrodes the concrete foundations and eats at the structural beams. Fish will school in classrooms. Oysters will grow on submerged light poles. Religious leaders will blame sinners for the drowning of the city. Journalists will arrive on floatplanes and write about the return of nature.
But mostly the city will be forgotten, one of many places lost to the attacking sea. In some distant future, someone, or some humanlike machines, may explore the sunken city and find bowling balls, stainless steel knives, gold wedding bands, and ceramic tiles. They may wonder about the people who lived there, what their lives were like, and what they were thinking as their world went under.