The move consists in invoking natural variability.
The idea behind such a move is made explicit in the following version (ht Tom Nelson):
How do you know that massive areas of ocean water haven’t naturally been as warmer or warmer on millions of other occasions?
Example. Until U can tell me exactly what caused Minoan/Roman/Medieval warm periods, Dark Ages/Little Ice Age cooling, early 20th cent. warming, & mid-20th cent. cooling, I refuse to believe U understand natural variability enough to rule it out as the #1 post-1970s warming cause