This picture from JPL shows that CO2 is pretty well mixed in the atmosphere. The mixing ratio is between 373 and 380 ppm in most places, it exceeds it at a few spots and it is lower at Antarctica. The colors exaggerate small differences which are certainly interesting, but do not seem to be very important for the greenhouse effect. Anthony Watts (Watts Up With That?) shows this image to show that supposedly CO2 is not well mixed. But overall, compared with the preindustrial level of 280 ppm, it is relatively uniformly distributed. Watts complains:
My question is: how does this global variance translate into the phrase “well-mixed” when used to describe global CO2 distribution? It would seem that if it were truly “well-mixed”, we’d see only minor variances on the order of a couple of PPM. Yet clearly we have significant regional and hemispheric variance.
And yet, “minor variances on the order of a couple of PPM” is exactly what we see.
Watts also repeats the old canard implies that since CO2 were made on Mount Loa, which is a volcano, they could not be reliable, but actually measurements are made globally – and the graphic above, that Watts shows in the same blog entry, shows that the measurements agree with the satellite data. Also, observe the remarkable absence of higher mixing ratios at locations with volcanic activity, for example Iceland or Hawaii.
So, Watt’s wrong?
Update: See also Mauno Loa is a volcano, so what?