Watch | How 2015 became the hottest year ever recorded

It's official! The National Oceanic Atmospheric Administration and NASA have announced that 2015 was by far the hottest year in 136 years of record keeping. NASA says 2015 was 0.23 degrees warmer than the record set in 2014 and 1.6 degrees above the 20th century average. What factors contributed to this occurance and will 2016 become the new warmest year on record? Click to find out.