CO2 is a tiny part of the atmosphere yet has big effects. Which shows that making true claims isn’t enough: one must make relevant ones. Contrarians appeal to incredulity more than they express skepticism {1}.
This square is a bit silly, but pedagogical. It would be hard to argue that CO2 is both a trace gas and essential to life, v. #ButLife. Yet they are often seen hand in hand, or one after the other. Pointing out the contradiction helps. But to visualize the effects of CO2 is crucial: seeing is believing. Prepare a good stock of examples and you’re good to go.
Examples
So even if Australia somehow completely de-industrialised today and our contribution to global carbon emissions went from 1.3% to 0% a whopping 99.99998% of the atmosphere would be unaffected.
(Evan)
CO2 concentration in Earth’s atmosphere to the nearest hundredth of one percent: 1990: 0.04% […] 2020: 0.04%
(Luis)
Objections and Replies
Amount. There’s so little carbon dioxide in the atmosphere that—
☞ Here’s what 400 par per million looks like. If you paint your windows black the paint molecules will only be a tiny percentage of the total molecules in the glass; how could a trace substance like paint have such an impact on the amount of light passing through the window (H/T Vaughan)?
Cause. How can a trace gas suddenly cause a heat wave—
☞ Higher average temperatures lead to more frequent extremely hot days. Now, my turn: how can the few thousand brain cells that control breathing be responsible for the life of trillions of cells that make human beings?
Imbalance. The 0.5 to 1.0 W/m2 is much smaller—
☞ We might not want to observe a planet where energy imbalance is bigger that its natural energy flows. An A/C planet, perhaps?
Impact. CO2’s impact’s so small we barely can trace it—
☞ A 2% change in body temperature means death {2}.
Home. There is more CO2 inside your own home due to respiration—
☞ The gas in the home does not block infrared radiation to the same extent it blocks them in the atmosphere.
Low. 2 W/m² is too low to meaningfully—
☞ It only takes .7 W/m² to in or out of a glacial period. The .2 W/m² adds .12K/decade, and that doesn’t cover the energy passed to other air molecules (Dan).
Smol. 0.04% is small—
☞ Here is what 0.04% looks like. Here is 200, 380 and 600ppm of potassium permanganate. Only a thousandth of 1% of the water on Earth exists as water vapor in the atmosphere. 800 ppm or 0.08% is the limit of alcohol in blood when driving in the US.
Thermo. AGW is 0.00001% of the heat into thermodynamic system—
☞ Your incredulity is duly noted. In return, please rest assured that my toaster can make toasts even if it uses very little of the overall energy on Earth.
Unexplained. That does not explain anything—
☞ Each part of the Earth’s surface emits heat in the form of infrared (IR) radiation. The peak of this emission is right at the frequency where CO2 absorbs strongly. While the proportion of CO2 in the atmosphere is small, 380 parts per million or 0.038%, this is still a large number of molecules, large enough that near the surface, at wavelengths where CO2 absorbs, the average distance light will travel before being captured is a few meters (a couple of yards). See Eli’s Simplest Explanation for more details.
Notes
{1} Incredibilism. Rejecting the influence of CO2 on atmosphere is the purest form of climate denial, but sometimes the point only expresses incredulity.
{2} Kooninism. Inferring that because a percentage is small it should have small effects has been known as a kooninism, in honor of Steve Koonin.
Readings
2012-08; Incredibilism; contrarians appeal more to incredulity than the express skepticism.
2010-08; CO2 – An Insignificant Trace Gas? Part One
2010-05; The Simplest Explanation; Eli sometimes can be clear.
Climateball Episodes
2019-06; Kooninisms.
ClimateBall 