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 Adelie penguins! April 20, 2017 No ice April 10, 2017 Beetles in Alaska March 20, 2017 Leave a Reply Cancel reply Your email address will not be published.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.