One of the best arguments involves looking at the temperature graphs for the past 640,000 years and realizing the cycle has gone from ice age to warm period and back all those other times with nary an SUV or coal-fired power plant. If these things occurred in nature before without significant human intervention before, it stands to reason that we are not the driving force in the equation.
Sorry, but I don’t think that it is a particularly good argument either.
Because process A has happened in the past without human intervention, it doesn’t mean that humans aren’t having an effect on it now.
For example, there have been multiple waves of species extinction. But that doesn’t mean humans didn’t cause the loss of most of the megafauna of the Americas around 12,000 years ago.
BTW, I think that particular issue is not settled. But I’m correct that previous waves of extinction not being caused by humans does not prove this one wasn’t caused by people.
To my mind the best evidence against AGW is negative. The climate is an incredibly complicated system, and we don’t fully understand it.
If you actually get into the mechanics of the computer projections, most of the factors the feed into them can’t really be measured accurately. So they’re estimated, which is another way of saying “guessed at.”
Then how these factors interact and their feedback loops are to a great degree estimated.
They the data, consisting largely of guesses, is fed into a supercomputer and very precisely crunched.
What do you get when you number crunch guesses? A guess with a veneer of science and precision laid over it.