NOAA said the United States experienced its 23rd warmest year, with an average of 53.8 degrees Fahrenheit.
That’s about 1 degree above the 20th-century average. The agency said the high global temperatures are mainly due to increased concentrations of greenhouse gases in the atmosphere, principally carbon dioxide.
That gas is emitted by human activities that include burning at coal-fired power plants and the use of internal combustion engines used in most vehicles around the world.
The year 2011 also saw record-breaking weather extremes and disasters across the United States and various other locations around the world.
The World Meteorological Organization said in late December that initial analysis showed that 2011 was the 10th warmest on record.
NOAA’s analysis was based on more extensive calculations and an alternative method of determining average global temperatures.
Graphic Data: NOAA