The Arctic shattered heat records in the past year as unusually warm air triggered massive melting of ice and snow and a late fall freeze, US government scientists said on Tuesday.

The grim assessment came in the Arctic Report Card 2016, a peer-reviewed document by 61 scientists around the globe issued by the US National Oceanic and Atmospheric Administration.

The NOAA report covers from October 2015 to September 2016, a period it said the Arctic's average annual air temperature over land was the highest on record.