Wendy McElroy - November 26, 2009
Anthropogenic Global Warming (AGW) proponent Kevin Trenberth says "It is incontrovertible" that the world is warming as a result of human actions.
Those are not the words of a scientist. By definition, the conclusions of science are always controvertible, and open to refutation or revision. That's how science works.
Scientific method demands three things of a theory: that it be verifiable, falsifiable, and predictive.
Verifiable: others must be able to duplicate your work and get the same results.
Falsifiable: there must be some way to prove your theory wrong.
Predictive: it must explain something that competing theories do not. Ideally, it should predict something new which can then be tested and confirmed. (The latter is not always possible in some sciences, e.g., paleontology.)
These are why, for example, Creationism can never be considered "scientific" -- it predicts nothing, really explains nothing ("God made it that way"), and can't be falsified.
Now let's compare AGW with another scientific media storm, cold fusion:
Cold fusion was a scientific theory. Its progenitors were zealous about sending details of their experiment world-wide. (There was some speculation that they spread this far and wide for fear of their research being classified by the U.S. government.) Other interested researchers could duplicate their work. It made a prediction (neutron emission) that could not otherwise be explained. And it was falsifiable -- other researchers duplicated their work, did not get the same results, and most importantly did not see any neutrons. Even though their theory was wrong, it was scientific.
The work of the University of East Anglia's Climatic Research Unit (CRU), however, is not. First, their work is not verifiable, for the simple reason that they have refused to make available either their raw data or their computer models. Since their work is entirely based on computer modeling of data, you need both in order to verify it. For the same reason -- concealment -- their work can't be directly falsified. Their theory significantly fails to explain historically-known phenomena, and while it does offer a testable prediction (global warming), to the extent that that has been tested, it has fallen flat.
(One might argue that their work can be falsified, when their predictions fail. Unfortunately, when the temperature record doesn't match their model, they just revise the model to substitute the new temperature data as required. This is how Creationists respond to surprising new discoveries: "God made that, too.")
Can AGW be scientific? Sure. It begins with full publication of all data and computer models. (In fairness, some AGW researchers may do this; I'm speaking of the CRU.) Then it requires explaining something that competing theories cannot -- while leaving nothing inconvenient unexplained -- and making a prediction that can be tested. Finally, it requires a clear statement of what would prove AGW wrong -- something possible to test, not something which requires a time machine or interstellar travel -- and a willingness to accept the verdict.
The cold-fusion guys admitted that if there were no neutrons, there was no fusion. I've yet to hear an AGW proponent say that anything could disprove AGW. To them, it's "incontrovertible."