Among other things the global warming crusaders got wrong: skepticism is a virtue, not a vice.
In retrospect, we probably should have paid more attention when, around 2005, activists shifted their primary vocabulary from global warming to climate change to describe the impact of human beings on this biosphere we call the Earth. Both phrases had been around for a while, of course. Global warming got its modern start back in 1975, when the journal Science published a feature asking, “Are We on the Brink of a Pronounced Global Warming?” In one form or another, climate change has been in use since the physicist Joseph Fourier wrote of the greenhouse effect in the 1820s.
A young climate activist at a Hong Kong protest demanding action against global warming
For that matter, both are unexceptionable meteorological terms with reasonably clear meanings: global warming a particular species or instantiation of general changes in the globe’s climate. The public purpose of those words, however—the political intent: That was a different thing altogether. For decades, global warming seemed a powerful, dynamic term to use—an apocalyptic phrase that summoned a grim vision of the eschaton, our world reduced to a lifeless wasteland. The only trouble was that it required the world to be, you know, warming. Constantly. A cold winter, and people started to wonder. A chilly spring, and people started to doubt.
Recent news reports have been dominated by squabbles between Berkeley’s Richard Muller and Georgia Tech’s Judith Curry, both involved in research that led to the release of data in October from the Berkeley Earth Surface Temperatures study. Muller claims that the fact of global warming now leaves “little room for doubt,” while Curry tells the Daily Mail that there exists “no scientific basis for saying that warming hasn’t stopped.” And yet, even in the midst of touting the study, Muller admits that the Berkeley data show that temperatures have not risen over the last decade.
Which confirms, more or less, what seems to be emerging as the feeling of the general public: These recent winters have been cold, and the summers themselves not so hot. That, in turn, creates a problem, for no sense of impending apocalypse survives widespread disbelief. And so—right around the point where it all started to seem a little hard to swallow—the phrase climate change, more generic if less picturesque, began to slip into public pronouncements, supplanting the old, falsifiable term global warming. A bitter January in the Midwest could well be a sign of climate change. Hurricanes in the Caribbean, mudslides in Latin America, floods in Australia. Earthquakes, even. Everything and anything, the whole wild uncertainty of the world, proved that we were right to feel under the gun—faced with an eschatological doom of our own creation.
The more the term embraced, however, the less it explained. That’s not as contradictory as it may seem. There’s a simple epistemological process by which, as we move up the genus-species tree, we arrive at ideas that cover more cases but convey less information: Lots more mammals exist in general than marmosets in particular, but mammal doesn’t tell us as much about the beast in question as marmoset does. Move up high enough into the linguistic arbor, and you arrive at terms that refer to all but mean none: thing, for example, or being.
Or climate change, as far as that goes. The great emotional gain of the shift from global warming to climate change was that the name had become so generic that nothing imaginable could prove it wrong. Every shift in weather is a confirming instance. The only problem left was the pesky little scientific one that, well, nothing imaginable could prove it wrong. In its public use, in the mouths of activists and the titles of organizations such as the United Nations Framework Convention on Climate Change, the phrase had come to describe something nonfalsifiable.
This is what was in the background when Ivar Giaever, a Nobel laureate in physics, resigned recently from the American Physical Society—in protest over the society’s loudly declared position that evidence of human-caused climate change is “incontrovertible.” Giaever is not some committed global warming skeptic, but he decided that he just couldn’t stomach the claim that anything in science is incontrovertible. If you can’t imagine conditions under which it might be controverted, then you’re no longer doing science.
It was back in the 1930s that Karl Popper popularized the idea of falsifiability as a necessary property of a scientific proposition. Several of the intellectual currents of the era combined to make Popper’s work seem a major breakthrough. The mechanisms of inductive logic had become a crisis point in philosophy, for example, and the commonly used “fact-value distinction” lacked clarity.
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