The Curious Wavefunction

The Curious Wavefunction

Musings on chemistry and the history and philosophy of science

Friday levity: More CO2 will be better. Also, meth is good for you.


Image: Zmie Science

Since we were discussing the differences between climate change "skeptics" and "deniers" (or "denialists", whatever you want to call them) the other day this piece is timely. The Wall Street Journal is not exactly known for reasoned discussion of climate change, but this Op-Ed piece may set a new standard even for its own naysayers and skeptics. It's a piece by William Happer and Harrison Schmitt that's so one-sided, sparse on detail, misleading and ultimately pointless that I am wondering if it's a spoof.

Happer and Schmitt's thesis can be summed up in one line: More CO2 in the atmosphere is a good thing because it's good for one particular type of crop plant. That's basically it. No discussion of the downsides, not even a pretense of a balanced perspective. Unfortunately it's not hard to classify their piece as a denialist article because it conforms to some of the classic features of denial; it's entirely one sided, it's very short on detail, it does a poor job even with the little details that it does present and it simply ignores the massive amount of research done on the topic. In short it's grossly misleading.

First of all Happer and Schmitt simply dismiss any connection that might exist between CO2 levels and rising temperatures, in the process consigning a fair amount of basic physics and chemistry to the dustbin. There are no references and no actual discussion of why they don't believe there's a connection. That's a shoddy start to put it mildly; you would expect a legitimate skeptic to start with some actual evidence and references. Most of the article after that consists of a discussion of the differences between so-called C3 plants (like rice) and C4 plants (like corn and sugarcane). This is standard stuff found in college biochemistry textbooks, nothing revealing here. But Happer and Schmitt leverage a fundamental difference between the two - the fact that C4 plants can utilize CO2 more efficiently than C3 plants under certain conditions - into an argument for increasing CO2 levels in the atmosphere.

This of course completely ignores all the other potentially catastrophic effects that CO2 could have on agriculture, climate, biodiversity etc. You don't even have to be a big believer in climate change to realize that focusing on only a single effect of a parameter on a complicated system is just bad science. Happer and Schmitt's argument is akin to the argument that everyone should get themselves addicted to meth because one of meth's effects is euphoria. So ramping up meth consumption will make everyone feel happier, right?

But even if you consider that extremely narrowly defined effect of CO2 on C3 and C4 plants, there's still a problem. What's interesting is that the argument has been countered by Matt Ridley in the pages of this very publication:

But it is not quite that simple. Surprisingly, the C4 strategy first became common in the repeated ice ages that began about four million years ago. This was because the ice ages were a very dry time in the tropics and carbon-dioxide levels were very low—about half today's levels. C4 plants are better at scavenging carbon dioxide (the source of carbon for sugars) from the air and waste much less water doing so. In each glacial cold spell, forests gave way to seasonal grasslands on a huge scale. Only about 4% of plant species use C4, but nearly half of all grasses do, and grasses are among the newest kids on the ecological block.

So whereas rising temperatures benefit C4, rising carbon-dioxide levels do not. In fact, C3 plants get a greater boost from high carbon dioxide levels than C4. Nearly 500 separate experiments confirm that if carbon-dioxide levels roughly double from preindustrial levels, rice and wheat yields will be on average 36% and 33% higher, while corn yields will increase by only 24%.

So no, the situation is more subtle than the authors think. In fact I am surprised that, given that C4 plants actually do grow better at higher temperatures, Happer and Schmitt missed an opportunity for making the case for a warmer planet. In any case, there's a big difference between improving yields of C4 plants under controlled greenhouse conditions and expecting these yields to improve without affecting other components of the ecosystem by doing a giant planetary experiment.

There's other howlers in that piece, including the well-known chestnut that we shouldn't worry about increasing CO2 levels because those levels have been higher in the past.

The current levels of carbon dioxide in the earth's atmosphere, approaching 400 parts per million, are low by the standards of geological and plant evolutionary history. Levels were 3,000 ppm, or more, until the Paleogene period (beginning about 65 million years ago). For most plants, and for the animals and humans that use them, more carbon dioxide, far from being a "pollutant" in need of reduction, would be a benefit.

Right, so we are talking about a period when temperatures and sea levels were higher, giant exotic creatures ruled the land and seas, the world was as different from now as we can imagine and - and this is kind of crucial - human beings didn't exist. If I had a time machine I am not sure that's the period I would pick for a pleasant stroll in the park. Plus the rate at which CO2 levels increased then was much lower than that at which they are rising right now, so I am assuming life got a bit more time to adapt. Now I have no problem if Happer and Schmitt are making the argument that we should go back to what it was like 65 million years ago and all possibly die a collective death while the flora and fauna around us thrives. But I don't think that's what they are trying to say.

Making the argument that increased CO2 levels are ok because certain varieties of plants would thrive is at best a narrow and one-sided point of view suitable for a personal blog. But having this point of view pitched as an argument in the WSJ? These folks are giving climate change deniers a bad name.

The views expressed are those of the author and are not necessarily those of Scientific American.

Share this Article:


You must sign in or register as a member to submit a comment.

Email this Article