The latest National Climate Assessment, released Nov. 3, found the same thing countless other reports have found: Global warming is happening and human activity is driving most of it.
By itself, this restatement of scientific knowledge about climate change probably won’t change many minds among those who think the whole idea is a giant liberal conspiracy to impose the New World Order, or something like that. But it still should add weight to the case against climate skepticism.
To begin with, the Trump administration did not try to bury the report, which contradicts the view of the president and EPA administrator Scott Pruitt, among others. That might suggest a certain fatalism about holding back the inexorable tide of evidence.
More importantly, the assessment’s clear and firm language raises an essential point about the validity of doubt. “It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century,” the assessment concludes. “For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.”
Over the years, climate-change skeptics have tried to suggest alternative explanations for global warming — cosmic rays, solar activity, etc. But their alternative theories have not withstood scrutiny. By contrast, the anthropogenic thesis — the notion that human activity is causing climate change — has. Over and over again.
And that is telling. Because if the anthropogenic thesis were fundamentally flawed, then its flaws would grow more obvious with the passage of time. Eventually, climate scientists would be forced to acknowledge that the theory could not account for the facts. That hasn’t happened. New reports continue to find that (to borrow an old gag) Generalissimo Francisco Franco Is Still Dead.
Climate skeptics therefore have been forced to pick quarrels at the margins. A recent piece in The Wall Street Journal persuasively argues that the latest climate assessment leaves a misleading impression of climate change’s severity. It fails to note, for instance, that while the U.S. has suffered more heat waves in recent years, the frequency of heat waves has not changed substantially over the course of the past century.
Climate-change skeptics pounce on such flaws, and extrapolate from them to conclude that if one report about climate change is inaccurate in one area, then every report about climate change must be wrong about everything. That simply doesn’t follow.
All science is contingent. So it’s possible that a researcher somewhere will soon prove everything scientists thought they knew about climate change is wrong — just as someone could soon prove that our current understanding of gravity or evolution is wrong. But the odds against such things happening grow longer with each passing day.