The city of Bergen, on Norway’s west coast, is proud of its reputation as one of the rainiest cities in Europe.
On average, it gets more than 200 days of rain a year, amounting to about 8 feet of water.
“[It] influences the mornings, what to wear, what you are going to do … how much clothing you need,” said Stina Ellevseth Oseland, head of the climate department at Bergen’s urban environment agency.
Climate change, however, is causing Bergen’s weather patterns to shift, bringing more rain and periods of more intense rain. This has caused bottlenecks and flooding because the city’s stormwater system — the network of drains and pipes meant to move excess water out of the way — was not constructed to manage this volume of rain. Now, the city is working to create a solution for that excess water.
“Houses can have problems, having water coming up through their basements, and also water coming from the mountains through the houses,” said Ingrid Vatne, a stormwater engineer at Bergen Vann, the city’s water department.
To manage the changing rain, Bergen’s stormwater system needed to increase its capacity.
But instead of building bigger pipes, Bergen built rivers.
“When you have overflowing in a pipe, then suddenly, the water comes out and makes big problems somewhere,” said Magnar Sekse, director of Bergen Vann. “What we try to do now is lift up the rain and creeks at the surface again, so you can see the water at the top of the terrain.”
Bringing the stormwater systems to the surface is part of a citywide adaptation plan. The plan, informed by national guidelines, prioritizes using nature as a buffer to protect infrastructure against climate change. These are known as “nature-based solutions.” Other examples include restoring wetlands to protect against sea level rise, planting mangroves to shore up erosion or even covering roofs with plants to reduce localized heat.
“It really started off as this concept for ecosystem restoration,” said Jessica Lilquist, a postdoc at the University of Utrecht specializing in nature-based solutions. “But also, nature has these social benefits that can really bring a different type of wellness to communities, as well as helping them become more resilient to weather extremes.”
In Bergen, this kind of system is now the default for development. If a project cannot use this kind of system, whether it’s public or private, the developers must explain why and receive additional permits.
Nature-based solutions have also gained traction globally, and in 2020, the International Union for the Conservation of Nature published global standards to evaluate the credibility and quality of proposed projects.
In Bergen, the flagship solutions project is Mindemyren, a neighborhood development project and light rail extension.
Mindemyren sits in a valley flanked by two large mountains. Historically, the rain would rush down those sheer slopes into a river and wetland below, but developers buried the river in the 1950s as Bergen expanded.
When the city began extending the light rail through this area, authorities weren’t able to change the underlying infrastructure, so they carved out a new canal on top of the underground river. The canal runs alongside the rail tracks for roughly half a mile; the two channels work in tandem to significantly increase the capacity of the existing stormwater system.
“The idea is that all the water from the roofs [of homes in the area] are led down to this channel, and not into the pipes,” said Trude Haugen, a communications officer for the water department.
The canal is also dotted with rain gardens and plants to help absorb even more water. There are steppingstones and small pools for people to walk through, and eventually, Haugen said, it will serve as a transit corridor for fish.
In total, an estimated 50 projects — both public and private — have been completed in Bergen using nature-based solutions in the past 15 years, according to the climate department. This turn to nature-based solutions emerged out of a need for larger climate adaptation efforts.
“Precipitation [in Norway] has increased about 20% since 1990, but most of the increase has happened over the last 20 to 30 years,” said Harald Sodemann, a professor of meteorology at the University of Bergen.
“We are also exposed to the sea, and the sea level is rising,” he said, “so it’s this dual threat from both the rising seas and increasing rain we have here in Bergen.”
The inflection point, according to everyone interviewed for this story, was in 2005, when an extreme rain event triggered a landslide, killing several people. After this point, climate change, and explicitly climate adaptation, became a local and national priority.
“I think to many in Bergen, especially local authorities, regional authorities, it was kind of a wake-up call,” said Oseland, head of the climate department. “This is something that can and will happen here as well.”
But nature-based solutions can also have their hurdles. Typically, these projects have higher up-front costs, though supporters argue the longer-term maintenance is cheaper. For stormwater systems, they require more space than buried pipes, which can be harder to come by in old, densely constructed cities. And if they are not planned precisely, they can redirect water that causes problems elsewhere for other infrastructure.
In Bergen, city authorities say the pros outweigh the cons, and the city has emerged as a leader.
“We need to develop the city in a way that allows the water to flow,” Oseland explained, “because it will flow, it will be here and it will increase.”
Nature-based solutions, she said, are important tools to adapt to the changing climate and live with the changes that are already here.