The planet is warming faster than ever, and as it does, extreme weather is intensifying. Of those events, almost half involve flooding. So to protect the world’s coastal cities and the hundreds of millions who live in them, engineers are creating some unique—and in many cases colossal—solutions. Everything from space shuttle-sized flood tunnels to a seawall hundreds of miles long.

“If you look at a river in a dry period, it’s gentle, it’s nice. But overnight, it becomes like this monster,” said Victor Coenen, a project manager with engineering firm Witteveen + Bos. “This huge deluge of water destroying houses, killing people; How do you control this? How do you tame this monster?” On this episode of Bloomberg Primer, we reveal some of the answers, which are as surprising as they are innovative.

The business of adaptation—investing in climate resilience—is projected to be a $1.3 trillion market. In “Flood-Proof Cities,” Bloomberg Primer explores the ways in which urban centers are adapting to meet this moment.

In Saitama, just outside Tokyo, Japan has built the world’s largest underground flood tunnel system. Called the Metropolitan Area Outer Underground Discharge Channel, it protects the surrounding areas from floods by diverting water underground and pushing it out into a nearby river. The $2 billion project has been estimated to reduce flood damage by 90%.

Jakarta, the fastest sinking megacity in the world, is no stranger to adaptation. Its seawalls absorb and deflect waves, but there are downsides: they can harm nature and local communities. Those climate defenses have not been the solution Indonesia’s leaders hoped for, so now the government is working on a new, $80 billion seawall project. Additionally, the Southeast Asian nation is designing a brand new capital city, Nusantara, that will be free of Jakarta’s coastal flooding challenges.

Smaller, more affordable projects can help mitigate flooding as well. In Nairobi, trash-eating flies are helping to stem rising waters during flash floods. Residents in the Mukuru area of the Kenyan capital are breeding millions of black soldier flies to consume garbage that collects in the city’s streets and clogs storm drains.

While all of these projects can help protect cities from disasters, they won’t stop the root cause—or prevent it from getting worse. “The trick is to use the need to adapt to then also motivate us to cut emissions more,” said Gernot Wagner, climate economist for Columbia Business School.