Hurricane Carol devastated the port of New Bedford in 1954, leaving millions of dollars of damage in its wake. The fishing community couldn’t risk another blow, so business leaders decided to construct a massive barrier at the mouth of the port.

The hurricane barrier is made of 900,000 tons of stone, 20 feet high and stretches 3.5 miles across New Bedford's port. It can protect New Bedford, Fairhaven and Acushnet from a Category 3 hurricane.

When a storm comes and the water level stops rising behind the barrier, it is “such a feeling of security,” John Bullard, the former mayor of New Bedford and president of the board of the New Bedford Ocean Cluster, told Boston Public Radio on Thursday. Bullard was 15 when the barrier was built.

Yet there are only five hurricane barriers on the East Coast. And coastal cities are facing growing threats from sea level rise and storm surge connected to climate change.

In 30 years, sea levels may be as much as 1.5 feet higher than they were in 2000. And by 2070, they may be as much as 3 feet higher, according topredictions from NOAA and Climate Ready Boston.

And that doesn’t include the extra feet from storm surge each time a Nor’easter rolls through.

Bullard suspects the high costs of large infrastructure projects are what’s stopping more cities, like Boston, from building something similar. The New Bedford barrier cost $18 million, equivalent to almost $200 million today.

“It's a crisis we're facing in climate change, but no one wants to act like it's a crisis,” Bullard said.

Enter the Emerald Tutu.

The Emerald Tutu — a play on Frederick Law Olmsted’s “Emerald Necklace” park network — is the green answer to more traditional, so-called “gray” infrastructure like seawalls and hard barriers. It’s an interconnected network of floating wetlands. Each circular pod is about five feet in diameter and is made of a spiral of marsh grass held together by coconut fiber rope.

“They’re kind of flattish, pancake things that float,” described Gabriel Cira, the project lead for the Emerald Tutu, on Boston Public Radio. “They ... flank vulnerable coastlines and really take the edge off of the worst storm conditions.”

Cira estimates about 10,000 of these units would be needed to protect the equivalent shoreline as the New Bedford hurricane barrier. Right now, the Emerald Tutu team has about 10 prototypes floating off Piers Park in East Boston. The long-term goal is to scale up the tutu to fit the needs of Boston’s coastline and create a protective, living shoreline that floats just off of the current shore. This would also avoid the challenges of working with so many property owners, Cira said.

“The key for nature-based solutions in general is ... the scale question,” Circa said. The team conducted lab studies at Oregon State University in a giant wave tank and observed a cumulative effect: the more units there are, the better they are dampening the wave energy.

He added that the Emerald Tutu team is in contact with Mayor Michelle Wu’s cabinet and he looks forward to a direct conversation with the mayor about implementing the Tutu on a bigger scale in Boston.

Bullard said he could see something like the Emerald Tutu being used in places outside the hurricane barrier.

“There are all kinds of things that go into creating resiliency,” he said.

Cira concurred. In general, he said, people want to believe that there’s one silver bullet to fight the threat of rising seas from climate change, be it a large infrastructure project or a fancy device.

“What we have to do is improve our cities, kind of square inch by square inch, and make them more resilient and adaptable and prepared,” he said.