A New Experiment Finds Only A 1.3°C Temperature Differential For Contained Air With 0.05% Versus 100% CO2

A new balloon experiment (inadvertently) demonstrates just how weak and inconsequential CO2’s warming effect is.

Levendis et al. (2020) tried using an experiment with air-filled (99% nitrogen and oxygen) versus CO2-filled (100% CO2) balloons to demonstrate a consequential warming effect for CO2. But their study may have demonstrated the opposite.

In the experiment a heat source was applied and then removed (shut off) to 3 different-sized balloons with 100% (1,000,000 ppm) CO2 in them. They compared the rate of cooling for these CO2-filled balloons to the cooling rate for a balloon filled with regular room air that has ~790,000 ppm nitrogen (N2), ~210,000 ppm oxygen (O2), ~9,000 ppm Argon (Ar), and ~500 ppm CO2.

The results revealed the temperature inside the 1,000,000 ppm CO2 balloons cooled just ~1.3°C (0.5 to 2.0°C) more slowly after 6½ minutes than the balloon with ambient air with ~500 ppm CO2. Put another way, raising CO2 concentrations from 500 ppm to 1,000,000 ppm only leads to a warming (reduced cooling) effect of 1.3°C.

Image Source: Levendis et al. (2020)
Perhaps recognizing it would not be helpful to the cause to publish an experiment exposing just how minuscule a warming effect CO2 has, Reviewer #2 sympathetically urged rejection of the paper for publication in its initial form and continued to criticize it after edits were made to the manuscript.
She or he suggested what’s being observed in Air-vs.-CO2 experiments like these is the comparison of convective heat transport for lighter N2 and O2 molecules relative to heavier CO2 molecules. In other words, this is a molecular density experiment and doesn’t represent the “actual physics of the greenhouse effect.”  Reviewer #2 even suggests “finessing” the paper with a disclaimer that says this is “not how CO2 warms the Earth” as she or he wonders aloud “what’s the point of publishing the paper”.
Image Source: Review history for Levendis et al., 2020

Reviewer #2 is correct. These lab experiments claiming to show CO2’s special role in the greenhouse effect only demonstrate denser molecules like CO2 (44 u) slow heat loss better than (29 u) lighter (N2 and O2, air) molecules, just as a heavier coat slows cooling better than a lighter coat.

In fact, Argon (Ar) has a much larger representation in the atmosphere (~9,000 ppm, or 0.9%) than CO2 does, but it is not considered a greenhouse gas that plays a role in the greenhouse effect. But as Wagoner and colleagues (2010) point out, Ar can be shown to reduce cooling (i.e., “cause” warming) with “identical” rates and magnitudes as CO2 molecules do in experiments like these because both Ar and CO2 have similar molecular densities (40 vs. 44 u) whereas N2 and O2 (29 u) do not.

Image Source: Wagoner et al., 2010

Wagoner and colleagues clearly affirm their support for the anthropogenic global warming (AGW) cause in their paper, but they seem to lamentably admit that a demonstration of CO2’s special and significant greenhouse effect role it “is difficult to demonstrate convincingly.” This is because the magnitude of the CO2’s radiative effect is already “more than an order of magnitude smaller” than observed in experiments like these that merely affirm the larger convective cooling reduction for denser vs. lighter molecules.

A real-world demonstration of CO2’s “specialness” as a greenhouse gas has yet to be observed.

via NoTricksZone


December 3, 2020 at 09:47AM

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