Addressing the Inevitable: How To Prepare for the Climate Change Flood

A few weeks ago, Ioane Teitiota, a resident of the island nation of Kiribati, climbed into a fishing boat with six other men for a trip to visit relatives in London, Paris and Poland. The passage took eight days, and when they arrived, London, Paris and Poland were virtually empty.

The three settlements on Kiribati's eastern atoll Kiritimati were once given those names by the British explorer James Cook. Now, London, Paris and Poland are halfway submerged. The strip of land has become so narrow that waves rolling in from one side crash into the sea on the other.

The dikes, the mangrove breakwaters and the cement walls weren't enough, leading the residents to abandon their homes to the ocean. London, Paris and Poland have gone under.

The country that Teitiota calls home has a population of around 110,000 people spread across 32 atolls and an island, small dots in the vast blue ocean distributed across an area as large as India. The country's average altitude isn't even 2 meters above sea level.

Fourteen-thousand kilometers away from Teitiota's fishing boat, on the other side of the world, London, Paris and Gdansk are located safely and securely above sea level. It is a completely different world. There is, in fact, only one thing connecting Europe's coastal cities with the Pacific atoll of Kiritimati.

The sea.

There is only one of them. It is the same water in Miami, Shanghai or the North Sea island of Hallig Hooge. And the sea is rising. Nobody knows for sure how quickly or how high the ocean level might ultimately rise. But rise it will.

On Monday, the United Nations Climate Change Conference began in the Polish city of Katowice, the focus of which is the implementation of the Paris Agreement -- following a summer of possibly record-breaking droughts and extreme hurricanes.

Three years ago, the international community agreed in Paris to limit the average global temperature increase to significantly below 2 degrees Celsius relative to pre-industrial levels. But the deluge has already begun. And it won't go away after 150 days like the one in the Bible. This one is here to stay.

It will take millennia for the polar ice caps to completely disappear, and perhaps they never will. But the fact that the sheet of ice covering Greenland is melting and the ice sheets of Antarctica are shifting, their edges breaking off more quickly, all of that can already be measured today.

There is a point of no return for the climate, and that point already lies behind us. The carbon dioxide is already in the atmosphere and it will remain there for longer than human civilization exists. And it will continue to warm the Earth's climate.

It is all really quite simple and follows the laws of physics: Water expands when it warms. Since industrialization, the Earth has warmed by about 1 degree Celsius, with the pace of warming having increased over the last several decades. Without an immediate and significant reduction in greenhouse gas emissions, NASA calculations indicate that an average temperature rise of 1.5 degrees Celsius will have been reached by the middle of this century. A further increase to 3 degrees above pre-industrial temperatures, according to a report compiled by the German Advisory Council on Global Change, would result in sea levels rising by 5 meters (16.5 feet), though it might take hundreds of years for that level to be reached. The uncertainties inherent in such calculations are, of course, significant. But determined action taken by the international community would render such uncertainties superfluous.

Every coastline is in danger of flooding, whether in Kiribati, Manhattan, Dhaka or Rotterdam. We are all, if you will, in the same boat.

Memories of vast floods are deeply embedded in human memory. For the Mesopotamians, floods were a punishment, an apocalypse that would swallow up all that was impure. Christians transformed the flood into a kind of global baptism, a vision of hope: Noah didn't sit around bemoaning his fate, he grabbed his tools and started preparing.

Building an Ark

That's what this text is about. Around the world, coastal residents, municipal authorities, urbanists, insurance underwriters and port engineers are hard at work building an ark. They are evaluating such concepts as floating homes and salt-resistant seeds, intelligent dikes and porous roads.

They are wondering whether it really makes sense that a quarter of the 100 busiest airports in the world are fewer than 10 meters above sea level. In Indonesia, they are making plans to move the capital city while the residents of Micronesia are buying land to ensure that they don't disappear. All are looking for ways to escape the water.

But what do we actually know today? What do we expect to happen and when? Who will be hit hardest? What can, what must, be done now? Is it sufficient to rely on technical solutions or do we have to radically change our approach?

A team of eight DER SPIEGEL reporters traveled to New Orleans and Bangladesh, to Venice and the Dutch island of Texel, and to Ioane Teitiota in the Pacific. Not to document the end of the world, but to emulate Noah's dove and its search for an olive branch. To search for models, initiatives, experiments and, ultimately, hope.

South Tarawa (Kiribati), 2 meters above sea level

Wearing nothing but shorts, Ioane Teitiota is lugging sandbags on the beach to stop the water that threatens his life and his country. He heaves them on top of each other, one after the other, constructing a wall together with tree-trunks and leaves in the hopes of protecting all he has from the ocean.

His home is a shack made of boards and bamboo, built in the shadow of a trio of screw pines. His wife, Angua Erika, sits out front in the sand wearing shell earrings and a Coca Cola T-shirt. She sings as she feeds the pigs.

It was once a paradise, says Teitiota, but the sea is angry, as though it has been bewitched. "It forces us to starve, to go thirsty and, in the end, to drown."

He's talking about the contaminated farmland and contaminated drinking water, and of the diseases that are spreading. Behind his home, he points into the stone well which provided them with fresh water for years -- but which now, with the seawater seeping ever further into the groundwater, is nothing but a salty puddle.

He points up into the breadfruit trees and to the palm orchards, from which they used to harvest large, sumptuous nuts, nourishing themselves from the copra, the coconut meat, inside. Now, for kilometer after kilometer along the coast, the leaves in the treetops are brown and dead.

Once he has finished building the protective wall, Teitiota kneels in the sand. He looks to the turquoise lagoon and says a quiet prayer, imploring God to spare his homeland for a bit longer, to keep the great flood away. His hands folded before him, he prays that before the water buries everything, his family might find shelter elsewhere.

Teitiota doesn't know for sure why the water surrounding the island he lives on keeps coming closer, nor has he calculated how much of his beach disappears under the waves each year. He doesn't know how much time he has left before Tarawa sinks beneath the waves for good.

But he has a plan.

Potsdam, 94 meters above sea level

The Potsdam Institute for Climate Impact Research (PIK) can be found on Telegraph Mountain, a terminal moraine deposited here in the last ice age. The institute is one of the world's leading climate change research centers and the way the brick building, with its trio of domes, perches on the hilltop is reminiscent of a spaceship that has just landed. Or perhaps an ark.

It's the right place to go to learn what the future holds. Researchers from PIK have been warning of the consequences of global warming since 1992. They have advised the German government and provided expertise to the European Commission and other national governments. They are part of international boards, panels and working groups.

Their voices are heard. And, sometimes, they are even listened to.

Currently, around 200 climate researchers show up every morning, most of them by bicycle, to switch on their computers and begin producing models, projections and concepts. They write code and draft scenarios highlighting the fragility of our societies and the interconnectedness of global systems. And they come up with possible solutions. Through the half-open office doors, you can see young scientists at their computers and the only clue to the region they are focusing on is provided by a photo on display or the occasional screen saver flitting across the screens: the Ganges Delta, the Amundsen Sea or deep in the granite of Svalbard.

Stefan Rahmstorf was one of the lead authors for the 2007 iteration of the Intergovernmental Panel on Climate Change, which won the Nobel Peace Prize that year. As a professor of ocean physics, he has become well-known in Germany and abroad, making frequent appearances at conferences and in the news. He is interviewed whenever the latest storm washes away yet another bit of the North Sea island of Sylt.

'The Preservation of Human Civilization Is at Stake'

In a quiet yet confident voice, Rahmstorf speaks of the end of the world as we know it. "The preservation of human civilization is at stake, that is true," he says.

Like most of his colleagues, Stefan Rahmstorf's world is one of comparisons: The curves become ever steeper, the amplitudes ever higher, the deviations from the norm ever more extreme.

"Unusually high ... systematic developments ... increasing numbers of extreme weather events:" Such are the phrases repeated over and over again in his presentations. The curves on his slides spike upward from left to right like the profit projections of an asset manager. It is the fever chart of the global climate.

DER SPIEGEL: How high will sea levels rise?

Rahmstorf: In the last 100 years, we have seen a rise of 20 centimeters. We will see that repeat in the next 30 or 40 years. If we quickly limit warming, we could escape in the end with an increase of half a meter. The current U.S. climate report, though, identifies 1 meter as the midrange scenario and 2 meters as the high end.

DER SPIEGEL: What does it depend on?

Rahmstorf: Whether the Paris Agreement is adhered to and average global warming is limited to significantly below 2 degrees Celsius.

DER SPIEGEL: That's not likely.

Rahmstorf: And it depends on how the ice sheet in Antarctica behaves.

DER SPIEGEL: Rather precariously.

Rahmstorf: And it depends on where on the globe you live, on the respective currents and winds. Even if the ocean is essentially the same one everywhere, the same can't be said of land. In some places, the ground is rising, as in Scandinavia, while in others, it is sinking, like along the southern Atlantic coast in the U.S. or along the North Sea.

DER SPIEGEL: What's the big deal with a couple of decimeters more or less?

Rahmstorf: Even just a couple-centimeter rise in the global sea level increases the risks associated with extreme weather events and makes storm surges and hurricanes more dangerous. Just ask the residents of Bangladesh.

Subhdia (Bangladesh), 6 meters above sea level

Rising sea levels don't present an insoluble problem for wealthy countries that can afford to protect their coastlines like the Netherlands and Germany. But Bangladesh is anything but prosperous. It is home to twice as many people as Germany crammed into a space that isn't even half as large. Two-thirds of the country is just a few meters above sea level and the majority of the population lives on the coast.

In the capital city of Dhaka, the ground is paved over in many areas so that water can no longer run off and the drainage system is often clogged up with plastic bags. Additionally, ground water levels are falling, which has meant that the already low-lying city is sinking even further.

When monsoon rains bloat the rivers, up to a quarter of the country floods. And when a dam breaks, villages can remain under water for years at a time. Some schoolchildren in the country have gotten used to wading home through chest-high water with their backpacks on their heads.

The farmers and fishermen make their living from and with the floods and have learned to tell the difference between good ones and bad ones. Good floods water the fields, but bad floods have become more frequent, washing away bridges and houses while driving away humans and animals. The frequency and intensity of flooding in the country will continue to increase. Last year, around 150 people died during the monsoon, with many millions suffering the effects.

When the sea level rises, entire regions could be submerged in 30 years and food production may collapse, forcing millions of people to emigrate.

Dhaka is now home to the International Center for Climate Change and Development, an institute that has begun to advise farmers to raise ducks instead of chickens, to farm fish instead of rice and to collect rainwater because fresh water is becoming scarcer. Years ago, researchers already began developing rice hybrids that can flourish in salt water.

In the last several years, the country has built more than 2,000 protective shelters along with thousands of kilometers of new dikes. There are floating gardens, hospitals on boats and homes on stilts. Bangladeshis in many areas of the country have long since begun living their lives in the upper floors of their homes because the ground floor is underwater.

Subhdia is located near the coast in the country's southwest, and thus in one of the most danger-prone regions of Bangladesh. Houses on stilts with roofs of straw line the shores. A woman wades through the water dragging a net behind her. Her name is Shulota Mandol, a small, roundish woman with a broad smile. She says she is now 47, the exact same age as her country -- and just as experienced when it comes to dealing with storm surges.

During the monsoon, she says, they hang their pots and rice from the ceiling and elevate the fireplace. They ram bamboo rods into the mud and build bridges, she says, adding that she can't remember a time when she wasn't wet. On one occasion, a storm cracked her house in two; on another, a cyclone took away all the family's possessions. Two years later, a wave -- taller than a man -- rolled through the village and the storm surge took away her house. And then? "Then we rebuilt it, but out of wood this time." Many of the hopes harbored by climate policy experts rest on the resilience of people like Mandol.

Two years ago, though, the Bangladeshi government had an idea along with a bit of money and it commissioned the aid organization Adams to carry out an experiment. They began pumping sediment out of the river and onto the banks, thus reducing the water level.

Since then, Mandol's home and the surrounding villages are all 1 meter higher. When it rains, the water flows off downhill. The chicken coop is on stilts and the outhouse on a block of cement.

Mandol is now able to plant bananas, whereas the trees used to just rot. The temple next to the house is also now elevated. Mandol has sacrificed part of her most valuable possession to her god: a dry bit of land.

Potsdam

Anders Levermann is a climate physicist at the Potsdam Institute and he also teaches at Columbia University. The illustrations that go along with this article are primarily based on his calculations.

DER SPIEGEL: A sea level rise of several meters: Is that what is awaiting us?

Levermann: That's what will happen if we continue on as we have been. But even then, it will only come in a few hundred years. Ultimately, after all, the sea level rise is a question of scale.

DER SPIEGEL: That sounds comforting.

Levermann: But we're talking here about oceans, enormous volumes of water. There is a vast amount of stagnancy involved and stagnancy is slow. Just imagine a sloth. But stagnancy combined with immensity, that is more like a boulder rolling downhill. It starts moving, accelerates, and then it can no longer be stopped. The amount of greenhouse gases we now emit within just a few decades will determine sea levels for many centuries.

DER SPIEGEL: For how long have you known that?

Levermann: In theory, for quite some time. But then there was that Monday in May 2014. That was a shock for me. I just sat there for a half-hour.

On that day, two studies appeared independently of each other about the West Antarctic. One of them focused on a model while the other presented new measurements. The results were consistent with each other: "Today, we present observational evidence that the (ice sheet) has gone into irreversible retreat," said Eric Rignot of the NASA Jet Propulsion Laboratory and the main author of one of the studies at a press conference. "It has reached the point of no return."

The Potsdam Institute was able to add an important detail.

Levermann: There is no natural stabilization mechanism. The glaciologists had suspected that West Antarctica could destabilize. It was a theoretical possibility. But then these measurements indicated that we had likely already passed beyond that tipping point. For us, it was a holy-shit moment.

Bremerhaven (Germany), 2 meters above sea level

The West Antarctic is ground zero for the rising sea level. As early as the 1970s, the glaciologist John Mercer had warned about the Antarctic ice sheet breaking off. Back then, though, few took him seriously. Today, we know that Mercer's concerns were accurate.

In Germany, the Alfred Wegener Institute for Polar and Marine Research is responsible for studying Antarctica and operates Germany's southernmost workplace, a research station on stilts called Neumayer III. The work done there is coordinated in a building complex in the port of Bremerhaven, located on Germany's North Sea coast. The dikes in Bremerhaven were recently enlarged, a direct consequence of what is happening 8,000 nautical miles away in Antarctica -- the same phenomenon that led Ioane Teitiota to construct a wall of sandbags at his island home in the South Pacific. It all has to do with West Antarctica, one of the perhaps decisive motors driving the rise in ocean levels -- one that feels far away, but which has effects close to home.

The glaciologist Angelika Humbert is, in a manner of speaking, at home in West Antarctica, though she is more familiar with the details of the modeled version than the realities of the continent itself. She got her start in quantum physics, but now her focus is on gigaton-heavy masses of ice. Humbert explains how the planet's ice began shifting and what that has to do with the dike out in front of her institute and how it will soon begin affecting the around 600 million people in the world who live in coastal areas.

It is helpful to imagine West Antarctica as a bowl with the ice inside measuring up to 3 kilometers thick and the bowl's lowest point lying below sea level. The entire bowl is tipped: Inland, the edge of the bowl juts up in the form of a mountain range. But on the other side, the edge doesn't even rise above the surface of the sea. The Circumpolar Current forces relatively warm, salt-rich water over the submerged edge of the bowl, which eats away at the underside of the ice sheet. Pieces of ice break off and float away. More ice flows in from the other side of the bowl.

Until 2012, Antarctica lost around 76 billion tons of ice per year, roughly twice the volume of Lake Constance. Since then, though, according to a recent report in the magazine Nature, this process has accelerated to 219 billion tons. That means that the ice from Antarctica is responsible for around a quarter of the global rise in the sea level. If the West Antarctic ice sheet were to collapse completely, it would translate into a global rise in ocean levels of more than 3 meters. "The fascinating question is how long it would take for that to happen and whether it would happen completely," says Humbert. "We won't have the 3 meters in 50 years, probably not even in 200 years. But that is the potential that is there."

The speed of these processes is particularly worrisome. "The glaciologists of the 1950s and 60s could never have imagined such a dynamic," Humbert says. "At the Jakobshavn Glacier in Greenland, the speed has tripled, from 5 kilometers per year to 17. That is extremely fast for glaciologists. And the acceleration has taken place within just a few years."

Humbert says she was shocked by her last flight over Greenland: "The loss of ice mass in Greenland has now reached the northeast. You fly over and all you see is a graveyard of icebergs." Last year, a 265-square-kilometer (102-square-mile) iceberg broke off from the Pine Island Glacier in Antarctica and floated out into the Amundsen Sea. Sea levels didn't rise as a consequence because the ice had already been lying on the water. But the glacier could no longer play the role of parking brake for the masses of ice further inland. West Antarctica has begun shifting, and it is a process that cannot be stopped any time soon. "The only thing that can be done is slow it down," says Humbert.

Potsdam

DER SPIEGEL: Humans start something, the dynamic intensifies and at some point, physics takes over.

Rahmstorf: Those are the tipping points. Here at the institute, we have identified around 10 of them.

DER SPIEGEL: For example?

Rahmstorf: The measurable deceleration of the Gulf Stream is one of them, as is the thawing of the permafrost in Siberia. Fellow researchers at the Alfred Wegener Institute have now discovered that rising ocean levels intensify the erosion of permafrost there. Which then releases methane and carbon dioxide.

DER SPIEGEL: Which then warms the planet.

Rahmstorf: It is a self-reinforcing process and can hardly be stopped.

Munich (Germany), 510 meters above sea level

In the insurance industry, natural catastrophes are referred to as "Nat Cats." And for the last 30 years, geophysicist Ernst Rauch has been keeping track of them for the insurance company Munich Re. Something really out of the ordinary has to happen to surprise him. Something like Hurricane Sandy.

When Hurricane Sandy finally left New York behind on the evening of Oct. 30, 2012, everything had changed. Large parts of Manhattan were flooded, subway tunnels were underwater and even the construction site of the 9/11 museum was hit. The power was out, the trains stopped running and Wall Street suspended trading.

A number of factors came together to magnify the storm's destructive power: its sheer strength, the rather unconventional path it followed, the powerful wind front that hit the coast perpendicularly, and a phase of the moon that intensified the storm surge.

But the calamity only reached the dimensions that it did because the sea level had risen over the past decades. At Battery Park on the southern tip of Manhattan, for example, it had risen around 35 centimeters in 93 years, with the trend accelerating. Flood protection was not prepared.

Sandy was a key moment for Ernst Rauch and others in his profession. The deluge had arrived, and it had to be priced in.

Reinsurance companies are the ones that insure insurance companies. They are needed when the risks are so great that they need to be distributed across several sets of shoulders. Last year was the most expensive one yet for insurance companies, with around $135 billion needed to pay for the damage caused in 2017 by such natural catastrophes as hurricanes Harvey, Irma and Maria. The three most expensive years in the industry's history have all occurred in the last 13 years.

Climate change isn't entirely responsible. More people are living in at-risk areas than ever and their possessions have increased in value. Pointing to the climate, though, does make it easier to convince customers to pay higher premiums. Rauch heads up a team of around 30 scientists who work for the company around the world. Their job is first and foremost to calculate as precisely as possible the chances that a catastrophe might take place. Secondly, they must put a price tag on the damage that catastrophe might cause. Thirdly, an appropriate premium must be calculated.

For all three of those tasks, there is NATHAN, the Natural Hazards Assessment Network, a digital platform that is constantly fed with information relevant for the climate. NATHAN makes it possible to better identify natural risks -- for every address around the world, down to a precision of 30 meters.

If, for example, you type in "New York, Battery Park," a wide, blue stripe appears around the southern tip of Manhattan showing the area that will likely be underwater in 100 years. The table next to it shows the "Risk Scores," which indicate the likelihood of flooding. The Risk Score for Battery Park is 38 out of 100. By way of comparison, not far from the French Quarter in New Orleans, which was hit hard by Hurricane Katrina in 2005, the Risk Score is 78.

Potsdam

A woman recently called PIK. She wanted to know if she should buy a piece of property in the Berlin suburb of Spandau and said she wasn't sure because of the rising sea level. You hear such crazy things, she said.

And it's true. There are now so many projections, scenarios and counterscenarios that some people haven't been able to keep up. But the UN Intergovernmental Panel on Climate Change (IPCC) is a good place to start for an overview of what is known, what can be known and what should be done as a consequence.

Anders Levermann is one of the 17 scientists belonging to the IPCC's Working Group I, which is responsible for the chapter on oceans and sea level. The IPCC, which is coordinated out of Geneva (390 meters above sea level) is a unique, global effort comparable to the Human Genome Project, which mapped the human gene sequence. It is a kind of think tank that issues regular reports on climate change and outlines the current state of knowledge with the greatest possible degree of transparency and with the goal of identifying practical consequences. Currently, IPCC scientists are working on the sixth report, which is being written by 220 leading authors from 60 different countries.

Levermann: First, you write down everything that should appear in the report -- with lots of placeholders because science isn't yet at the level we want to deliver. This "Zero Order Draft" is then sent around to colleagues and commented on. After that, a "First Order Draft" is written, already including graphics.

DER SPIEGEL: Who is allowed to comment?

Levermann: Every scientist can download it and comment. The authors must respond to every comment and each response is made public.

DER SPIEGEL: That must translate to hundreds of comments per chapter.

Levermann: Up to 10,000, yeah. It is a time consuming and stressful process. After that, the "Second Order Draft" is made public, on which anyone can comment.

DER SPIEGEL: And then?

Levermann: In the end, a synopsis of two to three dozen pages is produced, the "Summary for Policymakers." It is reviewed by politicians sentence by sentence, word by word, to make sure that all governments can sign it in the end. No politician, though, can change the actual report.