And once it thaws, that collapsing ground can drastically alter the vast expanse of the Arctic's tundra and boreal forest, and it can also threaten the homes and lifeways of Arctic residents.

一旦永久冻土开始融化，土会彻改变北极片苔原和北部针叶林，这也威胁着北极居民家园和生活方式。