The seasonal anomaly of the global average surface temperature in Summer (June to August) 2015 (i.e. the average of the near-surface air temperature over land and the SST) was +0.42°C above the 1981-2010 average (+0.76°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 0.67°C per century.
1st. 2015 (+0.42°C), 2nd. 2014 (+0.32°C), 3rd. 1998 (+0.28°C), 4th. 2012, 2010 (+0.23°C)