Uncertainty

Part 5 in a series of 5 for NextGen Journal
Read Part 1, Part 2, Part 3, and Part 4

Scientists can never say that something is 100% certain, but they can come pretty close. After a while, a theory becomes so strong that the academic community accepts it and moves on to more interesting problems. Replicating an experiment for the thousandth time just isn’t a good use of scientific resources. For example, conducting a medical trial to confirm that smoking increases one’s risk of cancer is no longer very useful; we covered that decades ago. Instead, a medical trial to test the effectiveness of different strategies to help people quit smoking will lead to much greater scientific and societal benefit.

In the same manner, scientists have known since the 1970s that human emissions of greenhouse gases are exerting a warming force on the climate. More recently, the warming started to show up, in certain patterns that confirm it is caused by our activities. These facts are no longer controversial in the scientific community (the opinion pages of newspapers are another story, though). While they will always have a tiny bit of uncertainty, it’s time to move on to more interesting problems. So where are the real uncertainties? What are the new frontiers of climate science?

First of all, projections of climate change depend on what the world decides to do about climate change – a metric that is more uncertain than any of the physics underlying our understanding of the problem. If we collectively step up and reduce our emissions, both quickly and significantly, the world won’t warm too much. If we ignore the problem and do nothing, it will warm a great deal. At this point, our actions could go either way.

Additionally, even though we know the world is going to warm, we don’t know exactly how much, even given a particular emission scenario. We don’t know exactly how sensitive the climate system is, because it’s quite a complex beast. However, using climate models and historical data, we can get an idea. Here is a probability density function for climate sensitivity: the greater the area under the curve at a specific point on the x-axis, the greater the probability that the climate sensitivity is equal to that value of x (IPCC, 2007):

This curve shows us that climate sensitivity is most likely around 3 degrees Celsius for every doubling of atmospheric carbon dixoide, since that’s where the area peaks. There’s a small chance that it’s less than that, so the world might warm a little less. But there’s a greater chance that climate sensitivity is greater than 3 degrees so the world will warm more. So this graph tells us something kind of scary: if we’re wrong about climate sensitivity being about 3 degrees, we’re probably wrong in the direction we don’t want – that is, the problem being worse than we expect. This metric has a lot to do with positive feedbacks (“vicious cycles” of warming) in the climate system.

Another area of uncertainty is precipitation. Temperature is a lot easier to forecast than precipitation, both regionally and globally. With global warming, the extra thermal energy in the climate system will lead to more water in the air, so there will be more precipitation overall – but the extra energy also drives evaporation of surface water to increase. Some areas will experience flooding, and some will experience drought; many areas will experience some of each, depending on the time of year. In summary, we will have more of each extreme when it comes to precipitation, but the when and where is highly uncertain.

Scientists are also unsure about the rate and extent of future sea level rise. Warming causes the sea to rise for two different reasons:

  1. Water expands as it warms, which is easy to model;
  2. Glaciers and ice sheets melt and fall into the ocean, which is very difficult to model.

If we cause the Earth to warm indefinitely, all the ice in the world will turn into water, but we won’t get that far (hopefully). So how much ice will melt, and how fast will it go? This depends on feedbacks in the climate system, glacial dynamics, and many other phenomena that are quantitatively poorly understood.

These examples of uncertainty in climate science, just a few of many, don’t give us an excuse to do nothing about the problem. As Brian, a Master’s student from Canada, wrote, “You don’t have to have the seventh decimal place filled in to see that the number isn’t looking good.”. We know that there is a problem, and it might be somewhat better or somewhat worse than scientists are currently predicting, but it won’t go away. As we noted above, in many cases it’s more likely to be worse than it is to be better. Even a shallow understanding of the implications of “worse” should be enough for anyone to see the necessity of action.

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Merchants of Doubt

I waited a long time to read this book – in retrospect, too long. I have long been a fan of Naomi Oreskes; I believe she is a brilliant and sensible scientist with a compelling way with words. On the other hand, nothing depresses me more quickly than reading about those who deliberately spread confusion on climate change for political reasons. After a particularly battering year for climate science in the public eye, I want to make sure I stay sane.

However, Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming, by Naomi Oreskes and Erik Conway, was oddly comforting. How could it be so, you might ask, given the subject matter?

It’s a good question. The book traces several key players, such as Frederick Seitz, S. Fred Singer, Bill Nierenberg, and Robert Jastrow, in their fight against mainstream science. Many of them were physicists in the era of atomic bomb development, and nearly all had been deeply influenced by the Cold War – they were anti-Communist to the point of extremism.

This extremism soon extended into science: any new discovery that seemed to necessitate government action was vehemently attacked by Seitz et al. Whether it was the harmful health effects of smoking, second-hand smoking, or DDT, and the existence of anthropogenic acid rain, ozone depletion, or climate change, the same people used the same strategies to sow doubt in the public mind, delaying the cry for action. The algorithm was relatively simple:

  • construct arguments against the phenomenon, which scientists had already addressed and ruled out
  • widely publish these arguments in the popular press, rather than scientific journals
  • demand that the mainstream media be neutral and provide “equal time” for their side of the so-called controversy
  • attack the professional integrity of the scientists who discovered and studied the phenomenon; label them as frauds and/or Communists
  • claim that action on this issue would be the beginning of the “slippery slope to socialism”

It’s enough to anger anyone who has the least bit of sympathy for science. The authors say it best:

Why would scientists dedicated to uncovering the truth about the natural world deliberately misrepresent the work of their own colleagues? Why would they spread accusations with no basis? Why would they refuse to correct their arguments once they had been shown to be incorrect? And why did the press continue to quote them, year after year, even as their claims were shown, one after another, to be false?

History repeated itself many times over, within the course of just a few decades. The attack against climate science that we are currently witnessing is just a larger-scale rehash of the pro-industry, anti-Communist fight against epidemiology, environmental chemistry, and so on. Until now, few attempts have been made to connect the dots, but Oreskes and Conway present a watertight and compelling thesis in Merchants of Doubt.

The hopeful part came when I realized this: all of the previous issues that Seitz et al attempted to discredit were eventually addressed, more or less successfully, by the government, even if some of the public is still confused about the science. Restrictions and regulations on smoking, along with education regarding its harms, has made tobacco use a semi-stigmatized practice in my generation, rather than a near-universal activity. The Montreal Protocol was largely a success, and stratospheric ozone is on the rise. The world, at least so far, has managed to avoid nuclear warfare.

Climate change is undoubtedly a more inevitable and wide-ranging problem, as it strikes at the heart of our fossil-fuel based economy, and will probably surpass, both in rate and magnitude, any change our species has seen in the global environment. However, since the attack against climate science has tracked so closely with previous campaigns, I can’t help but hope it will eventually end the same way: with the public and the government realizing the problem and employing effective measures to address it. I know it’s probably not very scientific of me to make this connection, but hope doesn’t have to be rational to be effective.

Ads Past and Present

Check out these unbelievable ads from the Tobacco Institute, which I found from the Tobacco Documents database. Click to enlarge.

And here is the tamest of the Heartland Institute’s full-page ads in the Washington Post (from a year or two ago, exact date unknown):

A Well-Documented Strategy

Exhibit A:

“There is no experimental data to support the hypothesis that smoking causes lung cancer, chronic obstructive pulmonary disease, emphysema, or chronic bronchitis………any number of things can influence the onset of a disease. The list includes genetics, diet, workplace environment, and stress…….we understand public anxiety about smoking causing disease, but are concerned that many of these much-publicized associations are ill-informed and misleading……….the media continue to uncritically accept and vigorously promote an anti-smoking agenda…….after hundreds of millions of dollars spent on clinical research, and decades of screaming headlines, we have no more certainty today about smoking causing disease than we did decades ago……….if even a small part of the time and money spent trying to link smoking to cancer were spent instead on studying the other causes of cancer, millions of lives could be saved.”

Exhibit B:

“The claim that human activities cause climate change has not been scientifically proven……….it is a reductionist error and not keeping with the current theories of climate science to attempt  to assign each temperature change to an exclusive single cause………..the use of results from flawed computer models to frighten people by attributing catastrophic future change to current human activities may be misleading and is highly regrettable……..that emotionalism can override objective analysis is illustrated by the headlines………..despite millions of dollars spent by the government on climate modeling and research, many questions about the relationship between human activities and global temperature change remain unanswered……….indeed, many scientists are becoming concerned that preoccupation with anthropogenic global warming may be both unfounded and dangerous – unfounded because evidence on many critical points is conflicting, dangerous because it diverts attention from other suspected hazards.”

Now read the originals.

Exhibit A

“There is no experimental data to support the hypothesis that increases in hydrocarbon use or in atmospheric carbon dioxide and other greenhouse gases are causing or can be expected to cause unfavourable changes in global temperatures, weather, or landscape…….any number of things can influence earth’s temperature. The list includes volcanic eruptions, variations in the amount of energy received from the sun, El Niños, and La Niñas – all of which are natural………we understand public anxiety about climate change, but are concerned that many of these much publicized predictions are ill-informed and misleading……….the media continue to uncritically accept and vigorously promote shrill global warming alarmism………after hundreds of millions of dollars spent on climate modeling, and decades of screaming headlines, we have no more certainty today about global warming prediction than we did decades ago………..if even a small part of the money spent trying to reduce carbon dioxide emissions were spent instead on fighting hunger or disease in Third World countries, millions of lives could be saved.”

-from the various articles on the Heartland Institute’s global warming page

Exhibit B

“The claim that cigarette smoking causes lung cancer has not been scientifically proven………..it is a reductionist error and not keeping with the current theories of cancer causation to attempt to assign each cancer to an exclusive single cause…………the use of results from flawed population studies to frighten people by attributing large numbers of death yearly to smoking may be misleading and is most regrettable……….that emotionalism can override objective analysis is illustrated by the headlines………despite millions of dollars spent by the government on smoking and health-related research, many questions about the relationship between smoking and disease remain unanswered…………indeed, many scientists are becoming concerned that preoccupation with smoking may be both unfounded and dangerous – unfounded because evidence on many critical points is conflicting, dangerous because it diverts attention from other suspected hazards.”

-from Smoking and Health: 1964-1979: The Continuing Controversy, published in 1979 by the Tobacco Institute

If I hadn’t told you which set of quotes was unchanged, and which I had replaced words like “smoking” and “cancer” with “human activities” and “climate change”, or vice versa, would you even have known the difference?