by Kenneth Richard
As CO2 Naturally Rises
from 0.1% to 75%,
Surface Temperatures Drops
Mofette fields are "natural carbon dioxide springs" that allow us to observe the effect that a 100% (1,000,000 ppm) CO2 concentration has on ecosystems, temperatures... even spiders (Spiders in mofette fields - Survival of the toughest in natural carbon dioxide springs - Balkenhol et al., 2016).
The scientists observed the site's CO2 rises daily from 1,000 ppm at 3:30 p.m. in the afternoon to 750,000 ppm by 7:00 a.m. the next morning.
The temperature changes associated with these extreme CO2 variations are about 33°C at 3:30 p.m., falling to 23°C by 7 a.m.
At a nearby site, where CO2 levels center around an ambient 360 ppm (1992 levels) throughout the day, Gardingen and colleagues observed temperature changes to be effectively identical to the Bossoleto site:
In other words,
This real-world temperature-CO2 experiment would appear to show CO2 varies in response to environmental factors, but it does not appear to causally affect temperature changes.
See "3. Results and discussion" at
Van Gardingen et al., 1995