2015 was the hottest on record as the chart predicted. Now 2016 is predicted to continue the upward trend. According to researchers at the University of Reading, UK anthropomorphic warming is due primarily to CO₂ emissions. In 2015, El Niño gave warming a slight boost, but they say the full impact of the natural cycle will occur this year. Carbon dioxide levels are above 400 ppm and are not expected to drop for the foreseeable future. This elevated level is in stark contrast to the 280ppm that prevailed before the Industrial Revolution. This fact makes 400ppm the hottest number on record.