The extent of sea ice in the Arctic and Antarctic last month was the lowest on record for January, the U.N. World Meteorological Organization said on Friday, while concentrations of carbon dioxide in the atmosphere hit a January record.

"The missing ice in both poles has been quite extraordinary," David Carlson, director of the World Climate Research Programme, told a U.N. briefing in Geneva.

"It is a quite strange situation. It's extraordinarily warm in the north, and the sea ice, which is one indicator of planetary warmth, is at a minimum at this point in both hemispheres."