The monthly anomaly of the global average surface temperature in December 2015 (i.e. the average of the near-surface air temperature over land and the SST) was +0.66°C above the 1981-2010 average (+1.04°C above the 20th century average), and was the warmest since 1891. On a longer time scale, global average surface temperatures have risen at a rate of about 0.74°C per century.
1st. 2015 (+0.66°C), 2nd. 2014 (+0.31°C), 3rd. 2006, 1997 (+0.28°C), 5th. 2003 (+0.25°C)