Judy Woodruff:

This week has brought another alarming milestone. Global greenhouse gas emissions hit a record level again last year.

As those heat-trapping gases increase, the Earth warms, melting even the thick ice in the Arctic that's supposed to remain permanently frozen. As a result, rising seas could threaten hundreds of millions of people worldwide, including in a small Alaskan village.

Stephanie Sy has the story of that village and its efforts to adapt.

It's part of our series on the Leading Edge of science, health and technology.