Researchers say they are seeing "rapid changes" in the Arctic as it comes under increasing stress from warming temperatures.
The annual State of the Artic report says sea ice is shrinking well below previous record-low levels and wildlife habitat is being changed. It also notes that permafrost is melting, shrubby vegetation has been colonizing tundra, and caribou populations are declining.
Scientists have expected polar regions to feel the first effects of global warming, and last year's initial State of the Arctic report provided a benchmark for tracking changes.
The National Oceanic and Atmospheric Administration says winter and spring temperatures were all above average throughout the whole Arctic. James Overland of NOAA's Pacific Marine Environmental Laboratory says 100 years ago, it would be warm in one part of the Arctic and cold in another, but that's not happening now.