Scientist on 1-20-16 released a startling statement that 2015 was the hottest year in the historical record breaking 2014 as the hottest year, in fact 2015 was 0.29 degrees Fahrenheit warmer than 2014 which is the most the record has ever been broken. Michael Mann uses the back to back records as evidence that the Earth is warming by saying it was incredibly unlikely for the Earth to not be warming. The scientists said that the overall reason was human influences on the climate specifically from greenhouse gases.

CO2 a greenhouse gas has reached its highest level in at least 800,000 years, 402 ppms, and could go back as far as 15 million years. However as climatologist Peter Gleick points out no matter how long ago that CO2 levels were this high never before has the climate been influenced by human behavior.

1.http://www.nytimes.com/2016/01/21/science/earth/2015-hottest-year-global-warming.html?ref=earth&_r=0

2.http://thinkprogress.org/climate/2014/04/09/3424704/carbon-dioxide-highest-level/