This is the third consecutive year a new global annual temperature record was set.
All 17 years of the 21century are included in the 18 warmest years in the modern record (1998 completes the top 18.)
Preliminary analysis puts 2017 as the warmest non-El Nino year.
It is increasingly likely the Earth is now warmer than at any time since the Eemian Interglacial, over 115,000 years ago.
The Eemian was warmer than the Holocene because of higher insolation.
Insolation refers to the amount of solar energy received per unit time at any one location, and it was higher due to astronomical cycles.