First, Do No Harm

by James Morris

This month, world leaders are meeting in Paris to discuss climate change. This time, there is optimism that concrete measures will be adopted to do something about this planetary problem.

Sadly, debates about whether climate change is real have slowed attempts to do something about it. In his recent op-ed in The Boston Globe, Freeman Dyson, professor emeritus at the Institute of Advanced Study at Princeton, writes (stunningly) that “the main effect of carbon dioxide on the ecology of the planet has nothing to do with climate.”

It’s hard to know where to begin with statements like this. Carbon dioxide is a greenhouse gas. This is a well-known fact, and is not in any way controversial. Greenhouse gases let sunlight through, but trap heat beneath them. In this way, they act like window panes in a greenhouse, or like a blanket covering the Earth. In fact, without carbon dioxide and other greenhouse gases like water vapor in the atmosphere, the Earth would be far colder than it is now. We couldn’t live without greenhouse gases.

So, to say that carbon dioxide has no effect on climate is simply incorrect. We can debate what the consequences will be of increased carbon dioxide in the atmosphere. And we can debate what we should do about it. But facts are not up for debate: we know that carbon dioxide is a greenhouse gas and therefore affects climate. And we know that carbon dioxide levels in the atmosphere are increasing.

Let’s put aside, however, for a moment the issue of whether climate change is real. Instead, let’s look at how we as a society might go about making decisions about complex problems.

Imagine you have a problem with your car. Let’s say it doesn’t start, or it makes a funny noise, or the window doesn’t go down the way it should. Who would you bring it to? An op-ed columnist with strong opinions about how cars work, or a car mechanic?

Now let’s consider something more serious – a brain tumor, for example. If I had a brain tumor, I would immediately consult a doctor, or a neurologist, or a neurosurgeon – again someone with lots of training, deep expertise, and years of experience.

So, why, in the case of climate change, do we listen to the thoughts and opinions of op-ed columnists, Presidential candidates, or the person on the street? Climate is a complex subject, involving weather patterns, wind and ocean currents, atmospheric chemistry, and the like. It’s hard to imagine why we as a society listen to and trust people with strong opinions, or a soap box to stand on, rather than scientists who know something about the topic.

In Harvard Square in Cambridge, Massachusetts, along Church Street close to where the movie theater used to be, there is a large mural by Be Sargent with the famous words of Rachel Carson – “Indication of harm, not proof of harm, is our call to action.”

RachelCarsonCarson was writing about the devastating use of pesticides and their effects on the environment. At the time, it wasn’t clear (there wasn’t proof) that they caused harm. But the possibility of harm was enough for her to call to action.

Climate change is similar. Imagine for a second that it is real and we do nothing about it. What will be the consequences? According to the models, rising sea levels, severe storms and drought, loss of glaciers and the polar ice sheets, and flooding of coastal and other low-lying areas. Many of these changes will disproportionately affect developing countries.

Now let’s consider the reverse – it isn’t real and we act. The consequences? We have cleaner, renewable energy. We don’t have to turn to hydraulic fracturing (or “fracking”), with its potential to pollute the groundwater, for sources of energy. We don’t have to depend on fossil fuels, which are a limited resource. Fossil fuels, after all, are the fossil remains of organisms that lived hundreds of millions of years ago – and they are neither renewable nor limitless.

Which would you choose?

Freeman Dyson also brings up uncertainty in climate modeling as part of his argument to do nothing about climate change. Here, he misses the point that uncertainty is part of the scientific process. I am a teacher, and my students often say that science proves this or that. That’s not the case. Outside of mathematics, there is really no such thing as proof in science.

Science really works by making observations, coming up with tentative explanations called hypotheses, doing experiments and making further observations to support or reject these hypotheses, and so on. Over time, we gain more confidence in our explanations and can explain a wider variety of observations, raising hypotheses to the level of theories. But science is at heart a humble enterprise, and we always recognize that our ideas can be modified as we learn more.

Just because there is some level of uncertainty, however, does not make all predictions the same or equally likely. As Mary Lefkowitz, another not-uncontroversial professor emerita, wrote, “…the absence of certainty does not mean that one interpretation is as valid as another. Probabilities and plausibilities matter, and when the evidence is less precise or less tangible than we would like it to be, some explanations are still more likely than others.”

© James Morris and Science Whys, 2015

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