A much-anticipated new report on how best to protect the Seaport District and other Boston neighborhoods from the effects of climate change finds that the cost to build a massive, multibillion-dollar wall in Boston Harbor is not worth the benefits.

Instead, it finds that the city of Boston and other coastal cities and towns should focus on more localized projects to counteract the flooding and higher sea levels wrought by global warming, said the report, which was compiled by researchers at the University of Massachusetts Boston and a handful of other organizations.

"Right now, it doesn't make sense for the city to consider any kind of harborwide barrier system," said the report's lead investigator, Paul Kirshen of UMass Boston's Sustainable Solutions Lab. "It doesn't make sense for decades, if not ever."

The report was sponsored by the Boston Green Ribbon Commission, a coalition of business and civic leaders formed more than a decade ago to help the city address climate change. Members include executives from General Electric Co., Boston Properties, Suffolk Construction and dozens of other local businesses. It was funded by the Barr Foundation, and its results are being announced a little more than a week before mayors from all over the nation gather in Boston for the International Mayors Climate Summit, to be hosted at Boston University on June 7.

The researchers were first tasked with studying a barrier in December 2016, but Boston businesses grew especially interested in their findings following the storms that caused flooding in the Seaport and other parts of the city this winter. Such flooding is expected to become more prevalent in the coming years and decades as climate change causes sea levels to rise.

The researchers studied three options for a harbor barrier to address climate change's effects on Boston's shores. They dismissed one as unworkable: An 18-mile dike stretching from Swampscott to Cohasset. Such a span would cost up to $85 billion to build and significantly disrupt both shipping and the environment, the report said.

The other two options are more feasible, the report found. One would stretch 3.8 miles from Winthrop to Hull and cost $8 billion to $11.8 billion to construct. It would be the largest barrier of its kind in the world, the report said. The other would fill the much smaller gap between the Seaport and Logan Airport and cost $6.5 billion to $8.7 billion to build. Both options would require other protection systems in coastal communities outside of the barrier's reach.

Either barrier could cut down on coastal flooding without significantly disrupting shipping or the environment, according to the report. But "shore-based" solutions, as the researchers call them, can provide the same level of protection at a cost of just $1 billion to $2 billion, with additional benefits to boot, Kershen told reporters Tuesday. Shore-based systems could include flood walls on a much smaller scale than a harborwide barrier, changes to zoning laws, and the raising of land using berms, among other projects.

Shore-based solutions could be built in a matter of years, while the Winthrop-to-Hull barrier likely would not be ready until 2050, according to the report.

A localized approach is also much more flexible than a massive barrier, the researchers said. Once the barrier is built, it can't be easily altered to reflect changes in either technology or climate change science, they said. Currently, the gates on such barriers are only built to close a handful of times each year, not with the once-a-week frequency that sea levels toward the end of the 21st century could require, according to the report.

Funding for shore-based solutions would likely have to come from federal and state governments as well as the private sector, said Bud Ris, a member of the Green Ribbon Commission and the former CEO of New England Aquarium. He floated the creation of more business improvement districts as one possible source of funding.

"We've seen a lot of interest, particularly in the business community, for tackling these problems. There's no question it's a big challenge to come up with that kind of money, $1 billion to $2 billion, but that's a lot easier" than the $8 billion to $11.8 billion the larger of the two feasible barrier options would require, Ris said.

The researchers said that in a few decades, the city should evaluate how localized approaches are working and reconsider the need for a harbor barrier.

In a statement, Austin Blackmon, the mayor's chief of environment, energy and open space, said the report shows the city's climate strategy is on the right track. "Our years of work are making projects like a deployable floodwall in the East Boston Greenway possible now," he said. "We look forward to taking more action and continuing to evaluate the most prudent ways to protect Boston."