South Pole's carbon dioxide at 4 mn-year high
According to the National Oceanic and Atmospheric Administration, carbon dioxide surpassed 400 parts-per-million at the South Pole for the first time in four million years on May 23. This was the last place where CO2 had not yet reached that mark, a researcher said and added, "Global CO2 levels will not return to values below 400 ppm in our lifetimes".