The global average surface temperature in 2011 was the ninth warmest
since 1880, according to NASA scientists. The finding continues a trend
in which nine of the 10 warmest years in the modern meteorological
record have occurred since the year 2000 (1998 was also in the top ten).
The average temperature around the globe in 2011 was 0.92 degrees F (0.51 C) warmer than the mid-20th century baseline.
Reds indicates temperatures higher than the average
during a baseline period of 1951-1980, while blues indicate lower
temperatures than the baseline average. The start year, 1880, is the year that scientists call the beginning of the “modern record.” 
While average global temperature fluctuates from year to year, scientists focus on the decadal trend. As greenhouse gas emissions and atmospheric carbon dioxide levels continue to rise, scientists expect the long-term temperature increase to continue.
The carbon dioxide level in the atmosphere was about 285 parts per
million in 1880, when the GISS global temperature record begins. By
1960, the average concentration had risen to about 315 parts per
million. Today it exceeds 390 parts per million and continues to rise at
an accelerating pace. www.nasa.gov
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