The City of Boston today released a climate change report that says the city could be in for more sea level rise, extreme heat waves and flooding than previously expected. The report also lays out dozens of strategies designed to help Boston reduce its greenhouse gas emissions and adapt to the effects of climate change that it is already too late to avoid.

The 407-page report is called Climate Ready Boston, and it builds on the city’s 2007 Climate Action Plan, which was updated in 2011 and 2014. Among its findings, which are based on new figures from a group of scientists overseen by the University of Massachusetts-Boston School for the Environment, is a projection for three to seven feet of sea level rise by the end of the century. With just three feet of sea level rise, a 1 percent storm (sometimes called a 100-year storm) would inundate many Boston neighborhoods, including Downtown, South Boston, East Boston and the South End.

Climate Ready Boston says that much sea level rise is likely to occur by 2070, unless global greenhouse gas emissions decrease sharply. Three feet of sea level rise could cost Boston $1.39 billion in yearly damages, according to the report.

It also forecasts the city will see 20 to 40 days above 90 degrees each year by 2030, compared to an historical average of 11 days per year now. And it predicts an increase in storms dumping at least 5 inches of rain on the city over a 24-hour period, which could cause severe flooding far from the coast.

“That’s kind of grim, but the good news is this report is telling us what we could do next,” said Austin Blackmon, the city’s chief of environment, energy and open space.

Earlier this year, Blackmon told The GroundTruth Project that Climate Ready Boston would be “the Moneyball of climate analysis,” and today Blackmon pointed to several recommendations in the report aimed at helping local government prioritize its wish list for climate adaptation.

The most bold proposal is a barrier that would close off all or part of Boston Harbor. Blackmon said that would cost $10 billion to $15 billion and could create more problems than it solves. A harbor barrier could disrupt commercial activity like shipping, for example, or create a black lagoon of pollution that is currently diluted and carried out to sea. The city is launching a feasibility study for the idea.

Other strategies for climate-proofing Boston are more modest, but would still require an overhaul of infrastructure planning on a scale seldom seen in American cities except after natural disasters. Those include temporary flood barriers and green buffer zones along the shoreline, dual-purpose “protective and floodable waterfront parks,” and a network of local electrical grids designed to keep running during major storms.

For a model Mayor Martin Walsh pointed to Denmark and the Netherlands, where long-term, mega-engineering projects and “building with nature” are the norm. Walsh signed a memorandum of understanding with the consul general of the Netherlands in 2015, and city officials including Blackmon visited the Netherlands for a “study tour” earlier this year. The Dutch engineering firm Arcadis is one of the authors of Climate Ready Boston, having contributed to the report’s vulnerability assessments.

Since 1991, Boston has suffered 21 weather events warranting federal or state disaster declarations. But so far the city has not had a “wake-up call” like New York did with Hurricane Sandy in 2012, or New Orleans with Hurricane Katrina in 2005—or for that matter the Netherlands, whose deadly North Sea Flood of 1953 gave rise to their modern system of flood control. Natural disasters typically bring in federal recovery money and build political will for investment in protection against the impacts of climate change.

Without federal money, it will be difficult to finance many of the initiatives Climate Ready Boston suggests. President-elect Trump has called climate change a “hoax” and nominated or appointed members of his transition team and potential cabinet who similarly flout the scientific consensus on manmade global warming, casting doubt on his appetite to fund infrastructure designed to deal with the effects of climate change.

Mayor Walsh declined to comment on Trump’s transition team and cabinet nominations at the release event for Climate Ready Boston, but suggested the President-Elect might change his mind on the issue while in office.

“In the next four years, we’re going to have a natural disaster somewhere in the country, and they’re going to realize it’s a real issue,” he said of the incoming Trump administration. “Look what’s happening all over the world. It’s a problem.”

Facing the prospect of billions of dollars in climate-related damages, and doing so in the absence of federal funding, Boston officials are starting where they can. The next step for Climate Ready Boston, Blackmon said, is a study funded by the Massachusetts Office of Coastal Zone Management that will zoom in on two high-risk areas of the city, Charlestown and East Boston, where barriers built in narrow flood pathways could prevent massive flooding inland.