I have made an important update to an earlier post here, Getting back to 350 ppm CO2: You can’t go home again.

The message, essentially based upon recent work Tokarska and Zickfield on one hand, and by The Global Carbon Project on the other make the calculation of geoengineering through clear air capture of CO₂ far more pessimistic than even the whopping cost numbers were before. (Thanks to Glen Peters for pointing me to the annual budget of Carbon compiled by the Global Carbon Project.)

See the post, but, in short, I forgot to account for CO₂ “dissolved” in oceans and terrestrial ecosystems which will come back into atmosphere in order to restore pCO₂ equilibrium once atmospheric concentrations are reduced.

You really can’t go home again ….

This all also reminds me of something I have written before. Forget the monuments, and the civilization, and the going to the Moon or Mars, and the libraries. In the long run, humanity’s legacy to Earth and the Universe will be the Carbon Dioxide we are emitting into the climate system. No other single action we can imagine doing in the foreseeable future will have such a widespread or a long-lasting impact. Right now, we are Carbon Dioxide.