“What happens in the Arctic doesn’t always stay in the Arctic,” said NOAA administrator Jane Lubchenco at a press briefing – the region can produce effects far to the south. Weather conditions in the US, sea level rise along coastlines and migratory bird patterns are among the effects of Arctic climate change, she said, adding that “conditions in the Arctic are changing in both expected and in sometimes surprising ways”.

Martin Jeffries of the US Office of Naval Research and the University of Alaska, one of three editors of the report, summarized some of its most significant points. In general, he said, “Arctic-wide air temperatures were unremarkable in the context of the last decade. Yet, there was continuing significant change in the cryosphere, our frozen world.”

Among key findings, Jeffries said, were record low sea ice extent in September, record low snow extent in June and record high subsurface permafrost temperatures. The changing ecosystem is marked by the near extinction of the arctic fox in northernmost Europe, where it competes with, and suffers predation by, the encroaching red fox as temperatures warm.

Of particular concern to scientists is the state of the Greenland ice pack. Jason Box of Ohio State University, US, who has studied Greenland for 20 years, described the summer of 2012 there as “astonishing”. It was the warmest summer in 170 years, he said, leading to “acceleration of surface melting, ice area loss and volume loss, contributing to sea level rise in an accelerated way”.

The Greenland melt season was the longest since satellite observations began in 1979 and included a rare melt event that covered almost the entire surface of the ice sheet, Box said. He attributed it in part to an anomalous pattern that brought warmer air from the south to Greenland for the sixth consecutive year. As a result, the ice sheet’s summer reflectivity decreased by 7%, causing solar energy absorption and leading to feedback effects. In addition, the loss of glacial ice to the sea increased significantly in 2012 compared with averages in recent decades, Box said.

Arctic snow cover set record lows in June, both in Eurasia and North America, continuing the trends of recent years, according to Jeffries. He concluded that the Arctic is entering a new state, due to decreased reflectivity of solar energy by the diminished sea ice and snow cover, causing increased solar energy absorption at twice the rate of lower latitudes. “This is what we call the Arctic amplification of global warming, a feature that was predicted 30 years ago and we are now seeing,” he said.

The 2012 Arctic Report Card was written by a record 141 scientists in 15 countries and was independently peer reviewed, said NOAA Administrator Lubchenco.