I was debating a warmist the other day who challenged me (and other skeptics) to explain what caused warming in the late 20th century. My answer, of course is very simple: I don’t know.
Many warmists seem to think that the debate is symmetrical: If the skeptics do not understand the climate, it weakens their position just like it would weaken the warmist position of the warmists do not understand the climate.
It seems to me this kind of thinking fundamentally misunderstands the nature of the debate. The warmists have the burden of proof and therefore the skeptics need not offer any kind of alternate explanation for late 20th century warming. It is sufficient for skeptics to point out the flaws in the warmists’ reasoning.
Of course, the irony here is that the warmists are just as ignorant as the skeptics as far as I can tell. I asked this particular warmist to explain what caused the early 20th century warming. I also asked this person to explain what caused the Little Ice Age. He confidently replied “sunspots.” However, he was unable to offer any specific evidence or arguments to back up his claim. Instead, he fell back on the traditional warmist refuge of arguing from authority. He cited 3 journal articles without bothering to quote them or summarize the evidence in support of his position. I looked up one of the articles at random — it didn’t even mention the Little Ice Age or early 20th century warming.
So the bottom line is that there is a double standard here: If the skeptics are ignorant or uncertain about what drives the climate, it does not hurt our position. If the warmists are ignorant or uncertain, it damages their position quite a lot.