Nearly half the citizens of the tiny Pacific Island nation have already applied in a lottery for Australian visas amid an existential threat from global warming and sea-level rise.

As sea levels rise, Australia said it would offer a special, first-of-its-kind “climate visa” to citizens of Tuvalu, a Polynesian island nation of atolls and sandbars where waters are eating away at the land.

The visa lottery opened last week, and already nearly half of Tuvalu’s population has applied.

By any measure, Tuvalu is one of the smallest countries in the world. It’s home to just 10,000 or so people scattered across nine small coral islands that add up to less than 10 square miles.

It has been losing land to rising seas and further losses could make it one of the first countries to become uninhabitable because of climate change.

Seawater is increasingly seeping into the country’s few drinking-water wells. Within a century, some scientists