In the realm of climate science, as in most topics, there exists a range of ideas as to what is going on, and what it means for the future.
At the risk of generalizing, the gamut looks something like this: Ultra-alarmists think that human greenhouse-gas-producing activities will vastly change the face of the planet and make the earth inhospitable for humans; they therefore demand large and immediate action to curtail greenhouse gas emissions.
Alarmists understand that human activities are changing the earth’s climate and think that the potential changes are sufficient to warrant some pre-emptive action to try to mitigate them.
Skeptics think that humans activities are changing the earth’s climate but, by and large, they think that the changes are not likely to be terribly disruptive (and even could be, in net, positive) and that drastic action to curtail greenhouse gas emissions is unnecessary, difficult, and ineffective.…
Just how much warming should we expect from rising levels of atmospheric greenhouse gases (GHGs)? The answer largely hinges on how much extra warming might be generated by the initial warming—that is, how strong (and in what direction) are the feedbacks from water vapor and clouds.
By most estimates (including climate model outcomes), these feedbacks are positive and result in about a doubling of the warming that would result from greenhouse gas increases alone. By others, however, the total feedbacks are negative,…