Where were you on November 11th 2015? Bob Henson [ @bhensonweather ] writing in Dr. Jeff Masters' WunderBlog just last week, makes the observation: The daily average concentration of carbon dioxide in the air that day at Hawaii’s Mauna Loa Observatory was 399.68 parts per million. On November 12 it rose to 401.64 ppm, and it’s quite possible that we’ll never see another day in…