Mudflats: The world's great coastal protectors

As muddy as they are flat, mudflats don't necessarily have the draw of golden sands and coastal cliffs, but in an era of rising sea levels, theses sprawling areas of intertidal zones offer unsung protection to shoreline communities all over the world. 

Nestled toward the upper reaches of the northern hemisphere, Germany might still seem largely out of reach of the long arm of global warming. But off the country's northwest coast are a handful of small marsh islands, home to a tiny population, where the realities of climate change are already lapping at the door. 

Known as Halligen, or hallig islands, they are unique in that even those that are inhabited are frequently flooded by the wilds of the North Sea that swirl around them. With few to no sea defenses to protect them, residents have lived with the encroaching salty waters for centuries, but as global sea levels rise, some locals on hallig Hooge are beginning to question how much longer they can realistically stay.

Across the Wadden Sea  — the world's largest tidal flat system and a UNESCO World Heritage site — from Hooge is the emerald green island of Pellworm. A remnant from a much larger area of coastal land that was swallowed during a savage storm surge hundreds of years ago, Pellworm is now completely surrounded by giant protective dikes. 

Locals will not countenance life without them. Their removal, says Knud Knudsen— a local who walks across the mudflats from Pellworm to Suderoog to deliver mail — would spell the end of the island where he has lived his whole life.

But it's not only land and all those it supports that is threatened by rising seas in this corner of Germany. The entire tidal flat system is at risk of drowning beneath the water that currently exposes its ever-changing shapes and sands twice daily. 

And that, in turn would leave the millions of birds that arrive from all corners of the world to nest, feed and breed in the mudflats and salt marshes, with nowhere to go. That, in Germany as in other areas of intertidal zones, would disrupt finely tuned ecosystems that are home to worms, snails, crabs, fish, seals, birds, dolphins and many more species beyond. 

It would also affect tourism and the way people live. In some low-lying areas around the world, conservationists are trying to find ways to work with the sea to meet the challenges of its assent. Rather than just relying on dikes and walls, they are making a case for returning sections of land to the sea through what is known as managed retreat, or managed realignment. It's a controversial process, but they argue that if it is adopted in the right locations, it can enable the ocean, wildlife and humans to live alongside one another.