From The Weekly Standard, The Party of Reason, by Jeff Bergner


Unrepeatable events like the evolution of the world’s species and the evolution of the world’s climate are inherently difficult to explain, and their future course is even harder to predict. Discernment of patterns over time does not constitute knowledge of future developments. The cyclical warming and cooling of the Earth over millennia is precisely not what is at stake; what is claimed is that man-made global warming is a new planetary phenomenon. In the absence of a hypothesis to account for the rate and direction of change, predictions of its future course are simple extrapolations from the past—that is, mere guesswork.

Even when there is such a hypothesis, predictions may be unwarranted. For example, evolutionary biology—which is held up by some climate change acolytes as the gold standard of settled science—teaches that species have adapted over time. With this theory in hand, evolutionary biology can infer the existence of certain intermediate life forms even in the absence of fossil evidence. If such fossils are found, their discovery supports the underlying theory.

But evolutionary biology does not predict the future course of evolution. Past experience suggests we should expect adaptation and natural selection to continue to operate. But evolutionary biology tells us nothing about the types, numbers, or characteristics of the species yet to come. If and when species evolve a certain way, all that can be said—after the fact—is that this must have come about through adaptation and natural selection. The ability to predict replicable events is one thing, the possibility of predicting the onetime evolution of the Earth, its species, and its climate quite another. In short, climate activists are asking far more of global warming models than is asked of evolutionary biology.

Today’s knowledge of global warming consists of longer and better records of temperatures observed around the world than ever before. This is historical knowledge. The careful recording of global temperatures over time is no different in principle from the recording of the U.S. unemployment rate or the rise and fall of kingdoms. From this kind of knowledge alone, nothing can be predicted about the future.

We also have models which purport to account for the rise of global temperatures, most of which focus heavily on carbon dioxide emissions as a “forcing” factor for global temperatures. The best, the Berkeley Earth Surface Temperature project, begins correlating temperatures and carbon dioxide levels in the mid-18th century, when global temperatures were beginning to rise. A persuasive model, however, would be able to map accurately earlier periods of rising and falling temperatures. More, it would contain within it an implicit hypothesis (about the climate sensitivity of the planet) that could generate a correct and potentially falsifiable prediction about the future. No model has done either. None predicted the relatively flat global temperatures of the past 17 years.