I got drawn in to a climate change discussion on Facebook last week. I’d been doing really well staying away from such things, but a friend specifically appealed to me for help addressing the issues with a video that has a strongly-expressed central geologic argument to support the position that ‘elevated atmospheric CO 2 is a good thing.’ I may have been recruited to this task because of my work developing curriculum that teaches students to identify logical fallacies in discussions of climate science for the InTeGrate project.

Anyhow, since I took the time and effort to do it, I figured it might be useful to share the results of my analysis here.

Here’s the video:

And here is my logical analysis / critique of the video, focusing on identifying logical fallacies:

There is a non sequitur argument presented at 1:00: that because organic life is based on carbon, therefore an excess amount of carbon dioxide in the atmosphere is not harmful. It doesn’t follow that that is true.

. Another is at 1:45, wherein he points out correctly that without greenhouse gases (he says CO 2 , but let’s be generous and assume he means all greenhouse gases) in the atmosphere, Earth would be a dead planet. That’s true – but it again doesn’t follow that a lot more of those gases would be a good thing. An analogy to help see the flaw in this argument: without water, we would die of dehydration. Therefore floods aren’t bad. It doesn’t follow. Ditto iodine: a little bit prevents goiter (good), therefore a lot must also be good (not true: it poisons you).

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I’d also point out here that the presence of CO 2 in a planetary atmosphere doesn’t guarantee life: Our neighbors, the dead planets Mars (atmosphere is 95.97% CO 2 ) and Venus (atmosphere is 96.5% CO 2 ) prove that point.

. At 1:58, he contrasts EPA’s labeling of CO2 as a “pollutant” with his own (valid) description of CO 2 as “an essential ingredient for life.” These two are not mutually exclusive. It’s all about the dose. Yes, CO 2 is essential for (most) life on our planet. Yes, it can still be a pollutant in spite of that. It’s all about the dose. It’s a category error.

. At 2:15, he says it’s misleading to describe the products of the C + O → CO 2 reaction as “carbon emissions” because CO 2 is not C. This seems to me to be one of those things that’s factually true but utterly beside the point. If we referred to them as “carbon dioxide emissions,” would that change anything about the essential aspects of the case? I like “carbon emissions” because I take a very carbon-cycle-based viewpoint of the issue. If you focus on the individual carbon atoms’ fates, you can see how they pass from one Earth reservoir (sedimentary rocks, plants/biosphere, atmosphere, ocean, mantle, etc.) to another. This is not something you could say is true of “carbon dioxide emissions.” Because of this, I find “carbon emissions” to be valid as a term describing what’s going on.

. He calls people like me CO 2 “alarmists” at 2:40: I’d expect my freshmen geology students to be able to identify that as a classic ad hominem attack. That’s Latin for name-calling, without addressing the substance of the argument.

. This is a big one: As far as facts go, the geologic perspective is a good one. I appreciate the approach – but it’s certainly spun in a not-the-whole-truth sort of way. At 2:50, he points out that for much of Earth history, CO 2 levels have been higher than they are today or have been in recent times (e.g. Pleistocene). This is true. We are currently living in an “icehouse” Earth as contrasted with a “hothouse” Earth (lacking glaciers, with higher sea levels, such as persisted during the Cretaceous). He gives the example of the Cambrian, with “10x” higher CO 2 than today. He doesn’t mention the lower solar output then. One of the neat things about our planet is that as the sun has gotten brighter, greenhouse gas concentrations have generally declined, keeping us in a “Goldilocks zone” where water can be a liquid and thus life can exist. He says “We are currently living in a low CO 2 era.” This is true for *the planet*, but it doesn’t follow that it’s true for *our species*. (In fact, CO 2 levels have never been higher for the species Homo sapiens than they are today.) It also fails to address rates of change, a matter of critical importance for other less adaptable species that are our neighbors in the biosphere. He goes on to discuss actual greenhouses and CO 2 fertilization. While it’s true that elevated atmospheric CO 2 levels boost productivity, it does not follow that this is the end of the story, that a “pro” cannot also be a “con.” In addition, I would note: the CO 2 fertilization effect (more efficient photosynthesis, extra resulting plant matter) is insufficient to remove all the anthropogenic CO2 (+9 gigatonnes C per year) from the atmosphere. That’s thought to result in an extra 3 Gt of C being pulled from the atmosphere annually, with another 2 Gt going into the oceans, resulting in a net atmospheric gain of 4 Gt per year. This NASA graphic makes the point well:

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Feeding more people with more plants is good – a point made by our rose-colored glasses narrator – but it’s not as simple as that. The story doesn’t end with extra food. A more complete picture would also include farming land lost to desertification, soil lost to erosion, oceanic dead zones due to fertilization, coral reef losses due to bleaching (and attendant loss of nursery space for marine fish, another major source of human food). This focus on “more carrots in CO 2 enriched greenhouses” intentionally distracts from a more complex reality. It’s cherry-picking of the first order. He cites satellite evidence of the ‘greening of the Earth.’ True: but again, it’s more complicated than that. Those same satellites detect declines in oceanic productivity and melting of glacial ice. Satellites are tools that measure reality. Reality has positive effects and negative ones, too. It’s dishonest to only focus on one.

. His conclusion: “We should celebrate CO 2 as the giver of life that it is.” True! But it’s not logically inconsistent that we should also fear it if it gets out of balance. Consider whether this analogue argument makes sense: We should celebrate sodium as the atom which allows our muscles to contract! Therefore we should all consume 10 pounds of rock salt today. Sorry: Non sequitur: It does not follow. Ask your doctor is 10 pounds of NaCl is right for you!

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(Ask your climate scientist if 410 ppm atmospheric CO 2 is right for you.)

The narrator’s argument fails on numerous fronts, most particularly the implication that if something has positive effects it therefore cannot have negative effects too. Is there anything I missed?