Last month was the hottest January since scientists began keeping temperature records in 1880, US officials said.
The global average land and ocean surface temperature in January was 1.14 degrees above the average January temperatures for the 20th century because of the changing climate, the National Oceanic and Atmospheric Administration said.
In parts of Russia, Scandinavia and eastern Canada, temperatures exceeded the average by 5C.
Warmer temperatures mean melting snow and ice. The extent of Arctic sea ice was 5.3 per cent below the average from 1981-2010, and Antarctic sea ice was 9.8 per cent below average.
The hottest January after the second hottest year on record “is one of those indications that things are warming dramatically”, said University of Illinois climate scientist Don Wuebbles.