This past March, carbon dioxide levels in the atmosphere hit the significant benchmark number of 400 parts per million. The Arctic reached 400 ppm in 2012, but now that number represents the global average CO2 concentration, according to the latest results from NOAA.
Michael Oppenheimer, a professor at Princeton University, explains that 400 ppm is so significant because it is the level “that climate scientists have identified as the beginning of the danger zone.” (Capital Weather Gang)
This global CO2 level is the highest concentration in the past 800,000 years, due primarily to the burning of fossil fuels and the resulting release of greenhouse gas. CO2 concentrations have increased 120 ppm since industrial times; half of this increase has occurred since the 1980s (NOAA).
— The Weather Network (@weathernetwork) May 8, 2015
NOAA collects this data by taking air samples at 40 different remote stations around the globe. By sampling at these remote locations, scientists are able to get a better idea of the global average – one that is not affected by human and natural forces.
James Butler, director of NOAA’s Global Monitoring Division stated the following about the irreversible affects of greenhouse gases:
“Elimination of about 80 percent of fossil fuel emissions would essentially stop the rise in carbon dioxide in the atmosphere, but concentrations of carbon dioxide would not start decreasing until even further reductions are made and then it would only do so slowly.”
NOAA’s report on the topic can be found here.