ANCHORAGE — It’s not springtime now in Alaska, it’s “break-up” — the end of safe travel on ice.

And in an era of climate change, break-up has been coming too soon, especially this year. The ice has become unpredictable, creating new, sometimes deadly hazards and a host of practical problems that disrupt the rhythms of everyday life.

The ice roads that carry freight in winter and spring have been going soft prematurely. Hunters cannot ride safely to their spring camps. Sled-dog races have been canceled. People traveling on frozen rivers by A.T.V. or snowmobile are falling through; some have died. Rescuers trying to reach them have been stymied by thin ice.

[Read more about why March 2019 in Alaska was 20 degrees hotter than usual.]

Alaskans are not just accustomed to hard-frozen winters, they depend on them — for essential transportation, subsistence hunting, industry and recreation. Frozen rivers connect rural villages the way highways connect the rest of the country.