In an era of climate change, Boston is a sitting duck for floods

In the meantime, some worry that Boston is a sitting duck for the next generation of powerful storms.

“We’re fundamentally unprotected and highly vulnerable,” said Marc Margulies, an architect and president of the Wharf District Council.

Since 1991, the city has weathered more than a dozen storms with flooding severe enough to trigger federal or state disaster declarations. Many point to an epic nor’easter that pounded the region in March 2018 as evidence.

The tide reached nearly 15 feet, flooding streets in East Boston, low-lying sections of Dorchester, and downtown, as well as Fort Point and the Seaport, where tidal surges submerged the decks of luxury waterfront condos. Storm water poured through the roof of the Aquarium station on the MBTA’s Blue Line and overcame a sea wall in the North End, flooding Langone Park.

This weekend’s rare early-fall nor’easter is expected to be intense, but only cause minor to moderate flooding in Boston.

On Thursday, Mayor Michelle Wu issued a coastal storm warning for much of the weekend and encouraged residents to stay indoors during the storm’s peak.

Chase Berkeley, chief of operations for the Boston Water and Sewer Commission, said the agency does not anticipate the projected rainfall will overwhelm the city’s drainage system, but the commission will have extra staff ready to address any flooding that does occur over the weekend.

Even if Boston emerges relatively unscathed this time, climate experts say that monster nor’easters are growing stronger.

Michael Mann, a University of Pennsylvania climate scientist, said human-caused global warming is leading to higher precipitation totals from these storms. A 2025 study he coauthored also indicates the strongest nor’easters are yet stronger still, driven by warmer ocean water that provides the storms with some of their energy and power. Over the past half-century, his study found, the wind speed of these nor’easters has grown by about 6 percent, increasing their destructive potential and size of their storm surges.

Shel Winkley, a meteorologist at Climate Central, said the ocean temperatures where the storm is developing east of North Carolina are roughly 2 degrees Fahrenheit warmer than average for this time of year — an outcome made up to 100 to 200 times more likely by climate change. The stretch of ocean this storm is crossing is also unusually warm.

“These waters would not be this warm without a fingerprint of climate change,” he said.

Even as the Army Corps’ big plan takes shape, Boston has already been at work shoring up potential weak spots: It’s committed or spent $139 million on coastal flood protections that measures integrated into upgrades at parks and barriers deployed before forecasted storms. The city has also invested in communicating with residents about expected flooding for upcoming storms.

Sizing up the potential of the current storm, Nayeli Rodriguez, deputy director of the city’s climate resilience office, believes Boston is “more prepared than ever.”

“I’m not concerned that anybody has been left out of our thinking,” she said.

Margulies, the Wharf District Council president, said some buildings along the waterfront are also taking matters into their own hands. He cited a recent $20 million project at Harbor Towers, a luxury residential complex near the New England Aquarium, that includes permanent and deployable flood barriers.

This approach, however, has its limits. “Whatever happens to those buildings, they become islands in a flooded city,” he said.

The city is preparing for a more than a 4-feet increase in sea levels by the end of the century. Stronger storms are also bringing flooding further inland. Officials estimate that a 100-year flood in the coming decades could inundate 2,100 buildings and cause roughly $2.3 billion in damages.

Boston is working with the Army Corps on the draft coastal defense plan, which was released in July, to build what would be one of the largest coastal flood protection systems in the country. It would transform the waterfront by constructing flood walls, levees, and other engineered solutions along 16 miles of vulnerable coastline in five neighborhoods — Charlestown, East Boston, downtown and the North End, South Boston, and Dorchester.

Brian Swett, Boston’s chief climate officer, said implementation of the plan would provide a major line of defense against catastrophic storms through 2090 by plugging 20 major flood pathways in vulnerable neighborhoods.

The Army Corps plans to present a final report to Congress in 2028. If the projects are authorized, the federal government could cover as much as 65 percent of the cost — an appealing proposition at a time when city and state governments are strapped for funds.

But the price tag is expected to be a significant hurdle. Boston has a $75 million coastal capital reserve that will be used to provide matching funds as needed. The Green Ribbon Commission, a group of business and civic leaders helping Boston meet its climate goals, is developing a financial blueprint looking at strategies to pay for these projects.

Federal funding could depend on the outcome of upcoming elections. Bud Ris, a senior adviser to the Green Ribbon Commission, said, “We want to be ready in 2028 with a comprehensive and quite specific plan for Boston’s waterfront, so that in a new administration, whether that’s Republican or Democrat or whatever, we can make a good case for funding.”

State money is another question. Margulies said some Massachusetts residents may balk at footing part of the cost of multibillion-dollar infrastructure in Boston, despite the city’s importance to the state economy and the price of inaction. The Army Corps estimates Boston would face more than $50 billion in losses if it does nothing.

“I fear it is going to take a really big storm for us to fully solidify our support for doing this project,” Margulies said.

The timeline for construction may also be extensive. Swett said some of the early projects are underway.

“We are on our way to mitigating the most significant risk to life and limb and property in a way that is responsible,” he said. The whole plan, however, could take two decades to complete.

Ken Mahan contributed to this report.

Kate Selig can be reached at kate.selig@globe.com. Follow her on X @kate_selig. Niki Griswold can be reached at niki.griswold@globe.com. Follow her @nikigriswold.