When catastrophic floods swept through continental Europe this summer, it tested decisions made by authorities years before.
In Germany, flood warnings for the worst-hit areas were sent out by the European Flood Awareness System four days before the disaster, but failed to filter down through regional and local authorities to reach residents on the ground. Many stayed in their homes, only realising the danger they were in when it was too late.
Many wartime-style emergency sirens had been removed or allowed to deteriorate after the cold war, and others failed when the electricity cut. The effectiveness of the modern alternatives of apps, emails and warning texts was patchy.
In the Netherlands, the scene was different. On successive days, thousands of people were ordered to evacuate from their homes as authorities deemed their areas to be at risk. News footage showed residents of the threatened villages leaving before any flooding hit, some leading pets and farm animals away down residential streets.
In the background was the inescapable wail of the public sirens, which are tested across the Netherlands on the first Monday of every month at noon, part of the country’s adaptation to living with much of its population protected from submergence by fallible dikes.
Though hundreds of Dutch houses were flooded to the point of uninhabitability, there were no deaths. In Germany, there were almost 200.
The extent of the damage caused shock in the affected countries, and a certain amount of surprise that such disasters could affect wealthy and placid parts of Europe.
But an increase in extreme weather events and flooding due to rising sea levels is now inevitable – and it will affect Europe, too.
“Even if we meet the Paris Agreement we will get some sea level rise,” says Marjolijn Haasnoot, an environmental scientist at the Deltares institute and a leading forecaster of sea level rise scenarios and policy options.
“And even at low levels, there are some places where there will be permanent submergence.”
Contingency planning and preparation for this will save lives and money. But it’s a neglected policy area: a gloomy topic, requiring effort today for the sake of tomorrow, that even climate change campaigners prefer to avoid in favour of the more positive story of what can still be done to avoid the worst.
A paper released this week in the journal Climate Risk Management underlined the importance of making policy now with this future change in mind.
Even with a sea level rise of about 15cm, the land where one million people live would be entirely submerged in the next few decades, according to the scenarios laid out. Some 83 million more people would live at risk of a major flood – the kind seen once a century. The numbers of people affected increase steeply with each centimetre.
Climate scientists work on the assumption that each degree of warming causes 2.3m of sea level rise. The Paris Agreement aims to limit warming to 2 degrees – and the world is on course to blow through that to 2.7 degrees, according to a United Nations forecast.
Haasnoot, the paper’s lead author, emphasises the importance of stopping building now in places that will soon be underwater or threatened by floods. They will become ever more expensive to defend from the water, and perhaps ultimately a lost cause.
“Some form of adaptation will be needed,” she said. “This takes time to plan and implement – measures can take decades. If you don’t prepare now you can get into a locked-in situation. You end up with no time left, and making investments that you lose in the future.”
Populations in east and south Asia are particularly at risk, but large numbers will also be affected in Africa and Europe too, according to the paper. Much of the risk in Europe will occur in coastal cities.
“We already know that Asia in particular has a large and increasing risk. But that does not mean it will not happen in Europe – and it will happen soon,” Haasnoot said.
The experience of the Netherlands, where Haasnoot is based, does offer lessons to other countries in the possibilities for adaptation. But it also demonstrates that developing areas that rely on flood defences is costly, and comes with a weighty safety responsibility to manage the risk. In her research, Haasnoot has mapped out scenarios for the country up to and including outright abandoning land back to the sea.
“In the future, the rate of change will be much greater than we have been dealing with,” she said. As the paper concludes: “Difficult decisions are inevitable.”