NOAA, NASA: 2015 was hottest on Earth by a wide margin

Climate conference
The National Oceanic Atmospheric Administration and NASA say 2015 was by far the hottest year in 136 years of record keeping. Scientists blame a combination of El Nino and increasing man-made global warming. Pictured are attendees at a climate conference in Le Bourget, France, last month.
Christophe Ena | AP 2015