Oren Cass explains in a National Review Online column that climate alarmists made a major error when they relied on insults to make their argument.

Framing the climate debate as one between noble keepers of the scientific flame and people akin to Nazis gave the former group license to say almost anything. To the casual observer, even the most egregious exaggeration about climate science could seem reasonable compared with its outright rejection. Thus, Obama’s assertion in his 2015 State of the Union address that “no challenge — no challenge — poses a greater threat to future generations than climate change” became widely accepted. When Senator Bernie Sanders warned during a presidential debate that “the scientific community is telling us that if we do not address the global crisis of climate change . . . the planet that we’re going to be leaving our kids and our grandchildren may well not be habitable,” he was not laughed off the stage. …

… And then a funny thing happened: “Denial” gave way to those more reasoned arguments. Perhaps the accumulation of scientific evidence changed minds. Perhaps it was only the political reality that sank in. Regardless, opponents of aggressive climate policy mostly stopped questioning whether the climate was warming and whether human activity played a role — the two points of agreement that define the famous “97 percent consensus” of climate scientists — and started explaining why that consensus did not justify costly and ineffective policies.

This shift in focus from the basic science of climate change to its public-policy implications has been a disaster for climate activists, exposing the flabbiness at the core of their position. Softened by years of punching down at their opponents’ worst arguments, they became addicted to asserting that “science says so,” and they are now lost when it doesn’t.