Real-World Outdoor Experiment: As CO2 Naturally Rises From 0.1% To 75%, Surface Temperatures Drop 10°C

At an outdoor test site in Italy CO2 concentrations vacillating between 1,000 and 750,000 ppm have no more or less an effect on local temperatures than a nearby site with stable, ambient (<400 ppm) CO2 concentrations.

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 (Balkenhol et al., 2016).

Temperature changes over the CO2-spewing Bossoleto spring in Tuscany, Italy, were measured over the course of a few days in the early 1990s by Gardingen et al., 1995.

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.

More specifically, when the Sun rises above the horizon, temperatures abruptly warm by 10°C and then CO2 rapidly falls from its morning peak (750,000 ppm) to its afternoon nadir (1,000 ppm).

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: 23°C at 7 a.m. and 33°C at 3:30 p.m.

In other words, the CO2 concentration – whether a stable 0.036% throughout the day or a wildly fluctuating 0.1% to 75% over the course of a 24-hour period – had no detectable effect on changes to the surface temperature.

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.

real world outdoor experiment as co2 naturally rises from 0 1 to 75 surface temperatures drop 10c

Image Source: Gardingen et al., 1995

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