For GSS Climate Change chapter 9. Excerpt: NASA scientists say 2013 tied with 2009 and 2006 for the seventh warmest year since 1880, continuing a long-term trend of rising global temperatures....  http://www.nasa.gov/press/2014/january/nasa-finds-2013-sustained-long-term-climate-warming-trend/#.Uuc5cPbTl9I. NASA RELEASE 14-024.
See also NOAA Global Analysis - Annual 2013 - http://www.ncdc.noaa.gov/sotc/global/2013/13