Warming in the Arctic was especially pronounced, and the area is warming about twice as fast as areas closer to the equator, the report found. On the other side of the Earth, the South Pole station recorded its all-time highest temperature of 9.9 degrees Fahrenheit (minus 12 degrees Celsius) on Dec. 25, breaking the previous record by more than 2 degrees F (1 degree C). Levels of Arctic ozone, which block UV rays, dipped to their lowest since records began in 1979.
The report also examined the year's extreme weather. Part of the weirdness arose from back-to-back cool spells in the Pacific Ocean, called La Niña episodes. La Niña, Spanish for "the girl," is a cyclical system of trade winds that cools the waters of the equatorial Pacific (El Niño is La Niña's warm-water counterpart).
La Niña helped drive heavy snowfall in the northern United States in early 2011, historic droughts in the southern United States in summer and an above average Atlantic hurricane season. It also played a role in record flooding in South America and Australia, which killed thousands of people, as well as a drought in east Africa that affected millions, said Thomas Karl, director of NOAA's National Climatic Data Center, in a teleconference.