Global temperatures in 2013 ranked as the fourth warmest on record, the National Oceanic and Atmospheric Administration announced on Tuesday.
This past year, the earth's temperature was 1.12 degrees Fahrenheit above the 20th century average of 57 degrees Fahrenheit. Continuing the upward trend in global temperatures, this is the 37th consecutive year that temperatures were above that average.
In 134 years of record-keeping, nine of the 10 warmest years have occurred since 2000.
Climate scientists are intrigued that 2013 did not feature an El Nino, whereas the three warmest years - 1998, 2005, and 2010 - did. Research suggests that the all-time record levels of carbon dioxide reached this past year could be the main contributing factor to 2013's warmth.
Long-range forecasts call for El Nino to return at the end of this year.
Meanwhile, temperatures across the Pioneer Valley were only 0.18 degrees Fahrenheit above normal in 2013, and much of the central United States actually had yearly temperatures slightly below normal in 2013.
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