In 2011, Earth’s atmosphere was cooler and drier than it had been the previous year, but it was more humid than the long-term average.

Despite the double-dip La Nina that occurred throughout the year, 2011 was still among the 15 warmest years on record. Including the 2011 temperature, the rate of warming since 1971 is now between 0.14° and 0.17° Celsius per decade (0.25°-0.31° Fahrenheit), and 0.71-0.77° Celsius per century (1.28°-1.39° F) since 1901.

NOAA scientists have documented a new impact of the increasingly thin blanket of Arctic sea ice: gases escaping from the thinner ice in spring are affecting air chemistry, reducing ground-level ozone, and likely increasing mercury contamination.

map of US winter temp anomalies 2011-2012

When NOAA’s National Climatic Data Center crunched the numbers for December, January and February—”meteorological” winter for 2011-2012—it stacked up as the fourth warmest of the past 117 winters. Virtually all of the West received less than its average precipitation.

The Arctic of recent years—warmer, greener, less icy—is likely to be the new normal for the Far North. One sign of the ongoing transformation of the Arctic is the spread of shrubs across the tundra.

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