MOSCOW — The recent diplomatic thaw between Russia and the United States over the crisis in Ukraine has had little impact there, but it is being felt somewhere else — in the Arctic Ocean, near the North Pole.

Out on the sea, the polar ice cap has been melting so quickly as global temperatures rise that once improbable ideas for commercial activities, including fishing near the North Pole, are quickly becoming realistic.

The United States, Russia and three other nations with Arctic Ocean coastlines agreed last year to regulate trawling in Arctic waters newly free of ice. But the deep freeze in East-West relations after Russia’s annexation of Crimea delayed the expected signing.

The day after Secretary of State John Kerry met with President Vladimir V. Putin in the Black Sea resort of Sochi last week, Russia announced it would sign the fishing agreement.