Boston has named the finalists in a competition for ideas of how the city can live with water. Officials say the city must adapt as climate change forces sea levels higher over the next several decades. Most of the submitted proposals assume large sections of the city will be submerged in the future.

Fifty teams from around the world submitted proposals. A jury of experts chose nine to move on to the final round of competition.

Winning ideas included surrendering sections of Boston to water; elevating streets; creating a network of canals; allowing first floors to flood; and creating incentives for private owners to sell flooded property to the city.

The competition judges acknowledged many challenges and obstacles stand in the way of implementing those ideas. Juror Matthew Kiefer, a land use attorney of the firm Goulston & Storrs, said it might take a crisis to spur support for public buyouts of private property.

“It’s really hard to take things away from people," Kiefer said. "And we’re taking things away from people. We’re taking away land — we’re taking away the bottom floor of their building — or whatever. It’s a really hard thing to do. And for government to be able to offer something in return requires you to give government resources at a time when we’re not great at giving government resources.”

The finalists now compete for a $20,000 grand prize. The winner will be announced in June.