In another first, 2015 was the fourth consecutive year that CO2 grew more than 2 ppm, said Pieter Tans, lead scientist of NOAA's Global Greenhouse Gas Reference Network, read the NOAA website.

“Carbon dioxide levels are increasing faster than they have in hundreds of thousands of years,” Tans said. “It’s explosive compared to natural processes.”

Levels of the greenhouse gas were independently measured by NOAA’s Earth System Research Laboratory and by the Scripps Institution of Oceanography.

In February 2016, the average global atmospheric CO2 level stood at 402.59 ppm. Prior to 1800, atmospheric CO2 averaged about 280 ppm.

The last time the Earth experienced such a sustained CO2 increase was between 17,000 and 11,000 years ago, when CO2 levels increased by 80 ppm. Today’s rate of increase is 200 times faster, said Tans.  

The big jump in CO2 is partially due to the current El Niño weather pattern, as forests, plantlife and other terrestrial systems responded to changes in weather, precipitation and drought. The largest previous increase occurred in 1998, also a strong El Niño year. Continued high emissions from fossil fuel consumption are driving the underlying growth rate over the past several years.