Climate change is transforming Arctic ecosystems in unprecedented and troubling ways, causing vast sheets of ice to melt, impacting local wildlife and threatening not just indigenous populations who live there, but communities around the world, researchers warned in a dramatic new report issued on Tuesday.

The findings were laid out in the 14th annual Arctic Report Card , compiled by more than 80 scientists for the National Oceanic and Atmospheric Association.

Researchers observed many troubling trends in the region : Temperatures in the Arctic were the second-warmest on record for an 11-month period ending in August. The permafrost continues to thaw, potentially releasing up to 600 million tons of carbon into the atmosphere each year. And some fish populations in the Bering Sea, which supplies about 40 percent of the American seafood catch, have begun to migrate north as waters warm, threatening food webs.