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Editorial: The ethics of experimentation

by Geoff Hart

Previously published as: Hart, G. 2006. Editorial: The ethics of experimentation. the Exchange 13(2):2, 5–7.

"[H]uman beings are now carrying out a large-scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future. Within a few centuries we are returning to the atmosphere and oceans the concentrated organic carbon stored in sedimentary rocks over hundreds of milllions of years. This experiment, if adequately documented, may yield a far-reaching insight into the processes determining weather and climate."—Roger Revelle and Hans Suess

[Editor's note: The source of this quote appears to be the following paper: Revelle, R., Suess, H.E. 1957. Carbon dioxide exchange between atmosphere and ocean and the question of an increase of atmospheric CO2 during the past decades. Tellus 9:18–27. Since I don't have a copy of this paper, I can't confirm this. Corrections gratefully received.—GH]

It's hard to imagine anyone living in the modern world who has not heard the terms greenhouse effect and global warming. Before moving on to the subject of this essay, it pays to take a step back and examine both terms to ensure that you understand what I'll be talking about. (Don't worry: this is about as technical and scientific as I'm going to get.) In short, and thus somewhat simplistically, the greenhouse effect refers to a process in which carbon dioxide produced by the burning of fossil fuels such as oil and coal is released into the atmosphere at a rate faster than it can be absorbed by living systems such as plants and inorganic processes such as absorption into seawater and chemical reactions with rocks and soils. A lesser-known but potentially more serious cause of the greenhouse effect relates to the release of trapped methane, whether from thawing of arctic permafrost (which permits increased decomposition of these huge deposits of organic matter, releasing methane) or a sudden release from clathrates composed of methane trapped in water ice that lie in large quantities on some parts of the sea floor. The greenhouse effect occurs because more of the longwave ("heat") radiation released as the Earth cools is trapped in the atmosphere by these gases and cannot escape into space, just like in a greenhouse; this is one cause—and possibly even the main one—of global warming.

It's the last clause that is the important part. No credible scientist doubts that atmospheric levels of carbon dioxide are rising. There have been countless measurements using a range of techniques that unequivocally demonstrate this change: carbon dioxide levels have risen from around 250 parts per million (ppm) before the industrial revolution to around 370 ppm today—an increase of roughly 50%. Even optimistic extrapolations of current trends predict a doubling of carbon dioxide levels within a century; pessimists predict an even scarier increase.

There's considerably more uncertainty and debate about whether global warming is occurring. There is an enormous body of good evidence that shows a strong warming trend over the past thousand years; in fact, I've edited a wide range of journal articles in recent years that leave me convinced our planet is warming, and possibly dramatically. But the problem in all such statements is that the most convincing measurements are direct ones, and we've only been doing these measurements for a few centuries—an insignificant proportion of the billion-plus-year history of life on Earth. The more-indirect measurements support the conclusions derived from the direct measurements, but rely on assumptions that are reasonable but not proven to the satisfaction of everyone in the scientific community. Much of this skepticism is appropriate, since as Carl Sagan observed, extreme claims require extreme proof. The problem is exacerbated by the large variations in temperatures, both locally and globally, that have occurred in recent centuries and over longer terms. These variations make it difficult to insist on the existence of a clear temperature increase caused by mankind; the overall pattern looks awfully convincing, but there's no smoking gun.

Last but not least, there's considerable doubt over the relationship between the carbon dioxide increase and global warming. There's a famous saying in the sciences that "correlation does not imply causality"—which in nonmathematical terms means only that two things may happen simultaneously by chance, not because one phenomenon causes the other. (Consider, for example, the near-100% correlation between watching television and dying before the age of 100. Nobody would argue that television itself kills us before our 200th birthday, despite the strength of the correlation.) We know that Earth's climate varies over time, with periodic ice ages recurring at intervals of tens of thousands of years; indeed, we are currently in the middle of the period that follows the most recent ice age, and some believe that any observations of global warming relate solely to the natural warming that follows an ice age. Fluctuations in climate also occur at shorter intervals; one of the most famous occurred from about 1550 to 1850 (depending on how you define the boundaries), a period of unusually cold weather referred to by historians as the "Little Ice Age". How can we distinguish between such long-term variations and the observed warming trend? We cannot—or at least not easily.

As noted in my February editorial, science progresses by making reasonable guesses called hypotheses that explain how the world works, testing these guesses, analyzing the results of those tests, and revising our model of reality accordingly. This ongoing process of refinement, sometimes accompanied by dramatic paradigm shifts, is one of the glories of science and possibly its greatest contribution to human history. But as I noted in that editorial, those who don't understand this model, or who understand it and pervert it to accomplish their own ends, subvert the power of the process by transforming that power into a weakness. This is nowhere so clear as it is in the current debate over the greenhouse effect and global warming. Both phenomena qualify as theories based on the definitions in my editorial: they have generated a great many testable hypotheses, and the results of these tests have largely supported the theories or been accommodated by relatively minor modifications of the theories. Moreover, increasingly sophisticated computer models show increasingly good simulation of the observed trends, suggesting that even though correlation does not imply causality, we seem to have discovered an underlying causality that can explain the observed changes and that is thus responsible for the correlation.

Those who would rather continue the status quo rather than facing a potentially disastrous reality, whatever the consequences of their shortsighted attitude, attack the proponents of the theories of global warming and the greenhouse effect based on a misunderstanding of how science works—or perhaps more cynically, based on a very deep understanding of how science works and how the general public misunderstands this process. Most cynically of all, some adopt the unethical attitude that it simply doesn't matter whether the proponents of these theories are right. (A brief etymological clarification: Although modern usage considers immorality to be a greater sin than unethical behavior, this actually reverses the denotation of the terms. Morality is inherently contextual, as in Cicero's exclamation Oh tempora! Oh mores!, and that context is the social environment of the time; in contrast, ethics addresses moral absolutes that are claimed to be true for all peoples and all times. I'll use that latter definition in the remainder of this essay.)

The argument has been made, most often by scientists, that science is inherently ethically neutral. Even if it is not, those who adopt this position fail to distinguish between ethics and morality, and based on this misunderstanding, state unequivocally that ethical principles are subjective, and thus irrelevant in the context of an ostensibly objective field such as science. On even cursory examination, this position is clearly indefensible; ethics applies to all human concerns, including science, and whether or not science itself is ethically neutral, scientists (being human) are not.

Those who reject the greenhouse effect and global warming theories may well prove to be correct. Having considered a large body of evidence, I don't personally believe this to be likely, but I must be true to my own knowledge of how science works and admit that at present, there remains considerable doubt as to the magnitude of the human impact on our environment. But these naysayers are standing on what is at best ethically questionable ground. Indeed, I'd go so far as to say their standpoint is entirely unethical—or immoral, if you want to use a word with more powerful emotional resonance despite my chosen definitions of the two words. Why? Because they cannot answer the following questions:

We know that pre-industrial humans evolved to breathe air with a carbon dioxide concentration of around 250 ppm. We also know that adaptations that have evolved over millions of years cannot change beyond a certain point on a time scale of decades. That being the case, a few telling questions: What is the effect of current levels of carbon dioxide (ca. 370 ppm) on human health? What is the limit of the human ability to adapt to increased carbon dioxide levels? At what level does carbon dioxide begin to suppress our ability to breathe? (Carbon dioxide is commonly used to extinguish fires by excluding the oxygen they need to burn. Human life can be extinguished at much lower concentrations.)
Where does the "tipping point" lie? A tipping point can be loosely defined as the point at which a process becomes irreversible; the famous leaning tower of Pisa is tipped over at a noticeable angle, and if the tilt increases sufficiently, it will inevitably fall over. At what level will global warming release the methane bound up in the arctic permafrost and at the bottom of the ocean? Methane is a more powerful greenhouse-effect gas that would dramatically accelerate the warming process, and there is credible evidence that some major species extinctions in the past resulted from catastrophic methane releases.

Because the potential consequences of the greenhouse effect and global warming would kill large numbers of humans, and might even be potentially fatal to our species, one must ask an ever harder question: Is it ethically defensible to run an experiment whose consequences could be so severe? Waiting until the effects of the current warming trend become unmistakable is conducting exactly such an experiment. In late 2005, Hurricane Katrina revealed, on a very small scale from the global perspective but on a very large scale from the human perspective, the consquences of willful ignorance and an unconscionable refusal to act in advance of a catastrophe. We can only hope that this lesson is not lost on those who have the power to affect our future environment and that of our children.

The argument that trying to reign in our environmental malpractice will cost us more than the benefits is demonstrably nonsense. Even if we exclude "intangible" benefits such as reducing the risk of catastrophe or improving future human health, there are clear tangible benefits. For example, the oil company BP (British Petroleum, though their new slogan for this acronym is "beyond petroleum") predicts that it will reduce its operating costs by US$650 million over a 10-year period by adopting more environmentally responsible practices that will also reduce its emissions of greenhouse gases by 10%. They're not alone in beginning such investigations. Moreover, I've yet to hear a good argument in favor of leaving all the lights on overnight in dozens of urban skyscrapers.

If these issues concern you, I urge you to become active in making your elected representatives aware of your concern. The Union of Concerned Scientists offers a good place to get started: their "advocacy resource page" (www.ucsusa.org) provides many good suggestions on how you can get involved in making change happen. After all, it's the ethical thing to do.