The scientists who have been agitating for measures to prevent global warming have become literally legendary.  In one of Aesop's fables, a host throws out a traveler for first blowing on his hands to warm them and then blowing on his soup to cool it.  After incessant warnings that our use of fossil fuels will cause an intolerable heating of our planet, climatologists have suddenly switched their tune and are now predicting that this warming will create a new ice age by altering the North Atlantic current.

Maybe they’re right, but I’m a bit skeptical.  As Randall Jarrell said, “acumen deserts intelligent men least when they are in the wrong.”  As a journal editor and reviewer of technical papers, I have marveled at how often scientists, when confronted with data that contradicts their theory, adroitly explain the offending data away or adjust the theory to suit the data.  And that’s what seems to be happening now.

Explanations are easy. An alternative explanation of recent paradoxes in climate phenomena was posted here earlier this year, and our readers could probably generate half a dozen others.  But proving the validity of any such theory is much harder.

A theory can be considered proved only when it predicts an unexpected event that is subsequently verified, as when Einstein predicted that, during a solar eclipse in 1919, a certain star would appear to be out of place.

In the absence of such predictions, scientists must at least try to be objective.  Karl Popper defined objectivity as a sincere and persistent effort to disprove one’s theory – e.g., by carefully designed experiments.  In the same spirit, physicist Alan Lightman recently recalled a 1975 Caltech commencement address by Richard Feynman, who “told us that before we went public with new scientific results, we should consider every conceivable way we might be wrong.”

The current “ice age” warnings might be right, but the reputation of climatologists for objectivity – which, for a scientist, is tantamount to a woman’s virginity – is in tatters after decades of relentless campaigning for the AGW cause.  As Aesop would put it, the boy has cried wolf once too often.