Two very different pictures of CO2 are again contending in the media. Reconciling these conflicting images remains a challenge in communicating climate change, but effective use of satire may be part of the solution.

When President Obama invoked the phrase “carbon pollution” 30 times in his climate policy address at Georgetown University last month, he was building on a thematic foundation that had been laid three weeks before.

At the end of May, the administration released its “Technical Update of the Social Cost of Carbon for Regulatory Impact Analysis.” In 21 pages, the administration enumerated and tallied detrimental impacts burning fossil fuels has on the nation’s economy, public health, and environment. This “technical support document” treated carbon as a pollutant, whose real costs were previously underestimated and externalized.*


Conservative critics pounced, mounting a counter-campaign focused largely on negative economic consequences they foresee from any effort to reduce greenhouse gas emissions. These predictions often carried dramatic headlines: “Obama’s Global Warming Folly“; “The Cost of War — on Coal“; “In the War on Coal, the Enemy is Us“; or “The War on Carbon (and Jobs) in the Motor City.”

Contesting Carbon’s Character

A few commentators, however, directly contested the carbon dioxide=pollution claim that underlay the administration’s strategy. Their efforts benefited from a piece published in The Wall Street Journal just three weeks before the White House adjusted the social cost of carbon. In their op-ed, “In Defense of Carbon Dioxide,” former astronaut Harrison H. Schmitt and Princeton physics professor William Happer argued that “the demonized chemical compound is a boon to plant life and has little correlation with global temperature” — this latter part in the face of seemingly overwhelming evidence to the contrary. In the op-eds, letters to the editors, and online comments written in response to Obama’s June 25 speech and its coverage, several others also defended CO2 by highlighting its service to plants.

Here’s Benjamin Zycher, visiting scholar at the American Enterprise Institute, wrapping up his lengthy piece on “‘Carbon Pollution’ and Wealth Redistribution” for AEI’s online magazine, The American:

In the Orwellian language of the environmental left, ‘carbon pollution’ is carbon dioxide — a natural substance that is not toxic to humans at many times greater than current ambient conditions and that protects plants from various environmental stresses.

Here’s an extract from a letter The Wall Street Journal published under the upbeat title, “Take a Deep Breath, Celebrate CO2“:

President Obama’s administration declares CO2 to be a pollutant under the Clean Air Act. But this gas is exhaled by all mammals, including we ignoramus humans, and is essential for the life of all green plants.

And here’s a comment posted in response to one of this website’s analyses of the President’s speech:

There will come a time when Green Activists will have to face up to the evil their belief in Catastrophic CO2 Climate Change Theory has exacted on Nature and Humanity . . . They will come to understand that increasing CO2 actually benefits the environment: Deserts bloom and plants bear more fruit.

This is the CO2-Is-Plant-Food argument, with a deep breathing exercise on the side.

Moving From Either/Or to Both/And

Carbon dioxide does indeed play a role in the biochemistry of plants. And elevated levels of CO2 will likely affect plant growth around the world, although exactly how this will net-out remains to be seen. Which species will benefit and which will be harmed, and to what extents, remains largely a function of just how high CO2 emissions and concentrations go.

By coincidence, the results of four different scientific studies were publicized in science and environmental news services even as the debate over Obama’s climate policies raged. One study even made its way into The New York Times. Not surprisingly, all then appeared in the weekly e-mails sent out by The Heartland Institute and the closely affiliated “Nongovernmental International Panel on Climate Change.”

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Conservative climate skeptics clearly think they have a case. Or rather, they think these studies about the “CO2 fertilization effect” buttress their case about the “slowdown in global warming,” a point highlighted in 12 of the 23 pieces analyzed for this post. In these polemical interpretations of the data, not only may CO2 be less culpable for global warming than supposed, it may also offer real benefits for agriculture.

At the end of weeks-long duels between the choruses of administration supporters and conservative critics, then, the public seems to face a stark policy choice: Should carbon dioxide be treated as a pollutant (as the Supreme Court decision in Massachusetts v. EPA has determined it to be) or as an essential nutrient?

The most simple and direct answer to this question is that it should be treated as both.

Worrying the Facts Versus Challenging the (Hidden) Premise

The CO2-Is-Plant-Food argument, at least as used by conservative climate skeptics, has two parts. The first is the “scientific” claim that CO2 is good for plants. The second is the policy implication: therefore, CO2 should not be regulated so as to slow or reverse its increase. But the implication only seems to follow from the claim. To actually get to this policy, one must also assume a broader rule or premise: things that are good for plants are not regulated.

One can challenge either part of the CO2-Is-Plant-Food argument. Most climate change communicators who have taken on the argument have focused on the first part; they carefully explain that the net results of increased CO2 levels, for the plants themselves and for humanity’s food security, may not be so clear.

Writer and film producer Adam Welz offers a good example of this approach in a June 13 piece posted at Yale Environment 360. An African savannah “greened” by the CO2 fertilization effect, scientists he interviewed suggested, may actually be less productive, for humans, because grazeable grasslands are replaced by scrub forests, which may then also tie up more of the ecosystem’s water resources. Each of the recent studies of the CO2 effect was accompanied by an analysis that raised questions about the net results (see here and here).

But it is the policy implication part of the CO2-Is-Plant-Food argument that is most vulnerable.

Re-Viewing the CEI Commercials

To see the real vulnerability of the CO2-Is-Plant-Food argument one need look no further than the two commercials the Competitive Enterprise Institute created in 2007 in response to Al Gore’s An Inconvenient Truth and to the Third Assessment Report of the Intergovernmental Panel on Climate Change. The two commercials have different emphases, “Energy” and “Glaciers,” but both emphasize CO2‘s links with breathing and with plants — “it’s what we breathe out, and plants breathe in.” And both end with the same kicker: “Carbon Dioxide: They Call It Pollution; We Call It Life.”

These commercials celebrate the reciprocal relationship humans and plants share through carbon dioxide. But the reciprocal relationship of plants and humans is actually much broader. Anyone who has tended a garden or lived on or near a farm knows that other substances come out of bodies that plants will gratefully take in. Indeed, darkly comic mystery writers will sometimes highlight a lush garden as a clue for those who know that plants also thrive on what oozes from human bodies as they decompose. To explode the policy implication of the CO2-Is-Plant-Food argument, then, one need only plug these other substances into the CEI kicker.

Urine: They Call It Pollution; We Call It Life.
Excrement: They Call It Pollution: We Call It Life.
Corpses: They Call It Pollution; We Call It Life

In fact, CO2 is exactly analogous to urine and excrement in one important respect: it’s a waste product of human metabolism. Nevertheless, important differences must be acknowledged. Carbon dioxide is wholly one substance (and a fairly simple one), and it’s far less dense, a gas rather than a liquid or solid. CO2 can thus diffuse through the environment much more rapidly than excrement or urine or corpses. This doesn’t negate the analogy, but it does require that the analogy be refined, which one can do by considering the problem of scale.

The Problem of Scale

Repugnant though they seem to us, urine, excrement, and corpses are no more toxic, in and of themselves, than CO2. But despite their benefits for plants, modern human communities have still chosen to regulate disposal of urine, excrement, and corpses. Why? Because even though not directly toxic, these bits of nature can alter local environments in ways that give rise to toxic or dangerous substances, organisms, or consequences.

It is not mere coincidence that plants take in the CO2 we exhale and that we breathe in the oxygen they produce in response. Nor is it mere coincidence that we eat many plants while they thrive on the wastes we produce as a consequence — including, at our deaths, the very flesh they nourished. Through these interrelationships, Earth’s ecosystems keep valuable materials in circulation.

But these ecosystems are not immutable. Overwhelm one side of the ledger and the rest of the system must find a new balance. It’s a matter of scale.

A very small village need not take great precautions in handling its dead or its wastes. If the village is sited on the banks of a major river, both can be dumped into the flowing waters without adversely affecting villagers’ health.

But as the village expands into a town and then into a city, its wastes and its dead become too much for the river to absorb and still retain its own ecological integrity. Algae, bacteria, diatoms, and/or fungi will displace more complex organisms, and in these degraded ecosystems organisms or byproducts that are deadly to humans can arise.

For these reasons, even though urine and excrement and corpses can increase plant growth, humans now carefully regulate the processing of sewage and corpses, especially in and around large cities. Major modern urban centers like London first developed comprehensive sewage systems shortly after global human population passed the one-billion mark.

From Exhaling to Exhausting

Human population has reached such a size that another waste product of its collective metabolism, CO2, is also now altering Earth’s ecosystems. But the real problem is not the CO2 exhaled by humans breathing — as some skeptics like to single-out — it is the gases and particles released by the fossil fuels that humans burn.**

The Competitive Enterprise Institute is not wrong to remind us that “the fuels that produce CO2 have freed us from a world of backbreaking labor, lighting our lives, allowing us to create and move the things we need, the people we love.” But it is wrong simply to assume that these benefits come without any environmental or societal costs.

Imagine, for a moment, the waste that would be produced if all the horsepower we harness in our vehicles, machines, and power plants was actually supplied by horses. (Former Secretary of Energy Steven Chu conducted a similar mental exercise in a speech he delivered in September 2011. Cities would be buried in manure. But instead of gathering and then disposing of the millions of tons of plant matter these horses would have consumed and then excreted, humans now burn high-density fuels — coal, natural gas, and oil — that were formed as, over millennia, millions of tons of plant matter were decomposed, fermented, condensed, and compacted. But this burning still produces wastes that interact with our ecosystems. This time, however, it is the global atmosphere — rather than a river flowing through a particular village or city — that is affected.

To avoid overwhelming the ecosystems on which they depend, humans in advanced societies process their liquid and solid wastes through large-scale civil-engineering systems. Is it really so surprising that with a global population that just passed the seven-billion mark, and with technologies that multiply the power of these 28 billion limbs by burning fossil fuels, humans need now to address the ecological consequences created by excreting so much CO2?

Upgrading Our Understanding of ‘Pollutant’

CO2 is indeed good for plants, and for some more is better. Higher levels of CO2 in the atmosphere will produce measurable “greening effects” in some, but not all, terrestrial ecosystems around the globe. But humans know from past experience with urine, excrement, and corpses that improved plant growth is not the only, and often not the most important, consequence of increasing the local or global levels of substances that come out of human bodies.

Focusing only on one aspect of CO2 or the other may make it more difficult for the public to recognize this fact. Thus the more important task for communicators may involve not merely providing Americans with new facts but smartly and sharply reminding them about the facts they already know — as, for example, to avoid their adverse side effects, humans have routinely regulated “plant foods.”

“CO2 Is Plant Food.” Conservative climate skeptics call this a sound argument. Climate change communicators should call it what it is: a clever sound-bite that depends on cherry-picked facts and on a major premise that is demonstrably false.

*Conservatives have responded to administration efforts to regulate carbon dioxide as if these entailed a radical re-definition of what we have traditionally meant by “pollution.” But as Mike MacCracken, Chief Scientist for Climate Change Programs at the Climate Institute, recently recalled in an extended analysis posted at CommentVisions, the first reference to CO2 as a “pollutant” (specifically, “the invisible pollutant”) appeared in a report drafted for President Johnson in 1965.
**Estimates of CO2 emitted each year as a result of energy and goods consumed by the average American run as high as 48 tons, but 20 tons is the most frequently cited figure. By contrast, different calculations of CO2 exhaled each year by the average human cluster somewhat more tightly around a much smaller number: ~330 kilograms. Because increases in human population are likely offset by decreases in animal populations, humans have probably not increased the CO2 content in the atmosphere through their breathing. But through the energy burned in powering machines and in producing goods for his or her lifestyle, each American adds 20 tons of CO2 to the atmosphere each year, roughly 60 times the amount of CO2 he or she exhales.

Michael Svoboda

Michael Svoboda

Michael Svoboda, Ph.D., is the Yale Climate Connections books editor. He is a professor in the University Writing Program at The George Washington University in Washington, D.C., where he has taught since...