Charles,
I am sorry to say that I have seen 606 ppm CO2 outside in a field and not next to a road or an emission source. The result was not an unusual occurrence. We were doing work on air based carbon capture in south London about a mile from the M25 motorway. On mornings that were foggy or had low hanging cloud we regularly saw results of 550 ppm or higher. Our suspicion is that the cloud or fog acts like a lid and allows the released CO2 from emission sources to build up. We found that if the sun started to burn the fog off, we could watch the CO2 level steadily fall before our eyes. It happened a fair percentage of the time over a three year period. Not uncommon at all. Dave -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
