"Settled" science of global warming?

I really liked this quote:

"President Obama has said that the science of global warming is 'beyond dispute,' and therefore settled. This is the justification for the imposition of a carbon cap-and-trade system that will cost $2 trillion. But Obama does not understand science. 'Settled science' is an oxymoron, and anyone who characterizes science as 'settled' or 'indisputable' is ignorant not only of science, but also history and philosophy. Aristotle, who lived and wrote in the fourth century B.C., was one of the greatest geniuses the world has ever known. He invented the discipline of logic, and founded the sciences of ecology and biology. Aristotle's physics were accepted as correct for nearly two thousand years. ... Aristotle taught that heavy objects fall faster than light ones. Over the centuries, a few unreasonable persons expressed skeptical concerns. But the consensus was that the physics of motion were described by Aristotle's dicta. The science was settled. Around the year 1591, an irascible young instructor at the University of Pisa demonstrated that Aristotle was wrong. He climbed to the top of the tower of Pisa and dropped cannonballs of unequal weight that hit the ground simultaneously. Aristotelean professors on the faculty were embarrassed. The university administration responded by not renewing Galileo's contract, thus ridding themselves of a troublemaker who challenged the accepted consensus. ... President Obama, a lawyer and politician, would now have us believe that the process of history has stopped. For the first time, scientific knowledge is not provisional and subject to revision, but final and settled. Skepticism, which has been the spur to all innovation and human progress, is unacceptable and must be condemned. But in fact, it is our awareness of what we do not know that determines our scientific level. ... Knowledge begins with skepticism and ends with conceit." --University of Oklahoma geologist David Deming