Post navigation Next ArticlePrevious Article science Parts per million ·June 19, 2017 ·Shen ·0 Comments The pre-industrial concentration of carbon dioxide in the atmosphere was 280 parts per million (ppm). As of December 2016, 404.93 ppm. (Source: National Wildlife Federation) Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on Google+ (Opens in new window) Related Tweet Share Pin it Comment Taggedclimate changeAside You May Also Like Once in every 2-3 years September 11, 2017 Meteors August 14, 2017 Hurricanes & Typhoons July 10, 2017 Leave a Reply Cancel reply Your email address will not be published. Required fields are marked *Name * Email * Website Comment Notify me of follow-up comments by email. Notify me of new posts by email.