Ice in the Arctic summer sea has been melting at almost record levels amid general temperature increases, according to an expert report released late on Thursday.

The review by the US National Oceanic and Atmospheric Administration (NOAA) warns that the Arctic's continued warming shows the dramatic effects of climate change even more than other regions.

Autumn air temperatures were a record 5 degrees Celsius above normal due to the amount of sea ice lost in recent years, according to the report.

"Changes in the arctic show a domino effect from multiple causes more clearly than in other regions," James Overland, oceanographer at the NOAA's Pacific Marine Environmental Laboratory and lead author of the report, told journalists.

The arctic is "a sensitive system and often reflects changes in relatively fast and dramatic ways," he added.

The loss of sea ice itself leads to further warming of the ocean, which together with rising air temperatures, affects land and marine life, the report said.

The year 2007 had been the warmest recorded since the trend of warming in the Arctic had begun in the mid-1960s.

Surface ice in Greenland has also been melting at higher rates this year, compared to 2007, prompting the NOAA to raise its warning from "yellow" to "red" in its annual report card on the effects of warming in the Arctic.