How many protestors dressed as dinosaurs to disparage fossil energy-tagged as symbols of activism in the first part of this editorial series-can define "climate sensitivity?" How many can explain why climate sensitivity is important to the politics of energy?
Probably not many. Most people, activists and otherwise, form opinions from what's reported by the popular news media. There, the standard message goes like this: A scientific consensus has formed around the near-certain proposition that human emissions of greenhouse gases, mostly carbon dioxide from combustion of oil, gas, and coal, account for most or all observed warming of the atmosphere and that halting a certainly dangerous trend requires a massive shift to energy from renewable sources. "The science" supporting this view is said to be settled.
Climate sensitivity
As popularly portrayed, "the science" seldom mentions climate sensitivity: the amount of temperature increase resulting from a doubling of CO2 in the atmosphere. In predictions of global average temperature during a period of CO2 build-up, that relationship obviously is critical. Yet climate sensitivity is poorly understood. "The science" concerning it is quite unsettled.
Predictions by computational models of dangerous global warming assume high climate sensitivity. That assumption must in turn assume that CO2, a trace gas, amplifies warming caused by a far more-abundant greenhouse gas, water vapor. Whether and to what degree that amplification occurs remain uncertain.
What's portrayed as the "settled science" that warns of catastrophic warming is, in fact, a theory. And it's a theory whose predictions can be tested by comparison with observation. If the predictions are wrong, something's wrong with the theory. That's how science works.
During the past 40 years, a period of rapid growth of CO2 in the atmosphere, global average temperature increased on average by one-half to one-third the rate predicted by models that assume high climate sensitivity. The temperature record thus weakens a theory already subject to question. CO2 has been much more abundant in the atmosphere than it is now during past ice ages. As a scientific theory, therefore, climate sensitivity remains a work in progress.
These observations neither deny the existence of a warming trend evident in the temperature record during the age of industrialization nor disprove that human activity, especially the burning of fossil fuels, contributes to the phenomenon. They do, however, imply limits to anthropogenic warming and therefore to the mitigation people can achieve by denying themselves the benefits of fossil energy.
But try telling that to a protestor in a dinosaur suit. To activists, human emissions of CO2-now ludicrously branded "carbon pollution"-represent a dire threat to humankind. To them the threat is certain and worthy of sacrificial remedies that take no account of cost. To them, after all, "the science" is settled.
The activists are simply wrong about that. Yet they have commandeered political and media discussion about climate change. They have fooled unquestioning news media with their simplistic diagnoses and persistent moralizing. They even managed to rebrand the issue from the original "global warming" after temperature trends flattened. And they are succeeding politically-blocking fossil-energy projects, winning lavish subsidies for nonfossil energy, and persuading international leaders who should know better to proclaim climate change the greatest threat of the age.
Activists-from those in dinosaur costumes in the streets to others in tailored suits in courtrooms-have turned science into a tool of propaganda serving a radical political agenda. Science has suffered as a result. Analysis and inquiry have given way to dogmatism and calumny. And some scientists have been complicit in the process.
Damaged credibility
Science is never settled. It challenges rather than pursues consensus. It exists to enlighten, not manipulate. And its credibility in the public arena has suffered.
Along with science, climate-change activism has damaged democratic processes. On that subject, more will appear in this space next week.
