SERUA ISLAND, FIJI – As the sun sets over Fiji’s tiny Serua Island, its climate-threatened inhabitants soak in one of the reasons they have rejected attempts to relocate their village — the “$100 million views.”

The island looks like a utopia from the mainland, two steep palm-covered knolls sandwiching its low-lying center, flanked by coral reefs and rich fishing grounds.

But it is on the island itself that the risk from rising seas becomes clearer, with a concrete sea wall providing the only defense against waves that are already swamping homes.

“The stronger the air pressure, the higher the waves.…