2011 is tied for the 10th hottest year since records began in 1850, the office said in its annual assessment of average global temperatures. The Arctic sea ice has also shrunk to record-low volumes this year, it said. The 13 hottest years on the books all have occurred in the last 15 years.
"The science is solid and proves unequivocally that the world is warming," said R.D.J. Lengoasa, deputy director of the International Meteorological Organization, and human activity is a significant contributor.