British-born physicist Freeman Dyson has revealed three "heresies", two of which challenge the current scientific orthodoxy that anthropogenic carbon causes climate change.

"The fuss about global warming is grossly exaggerated," writes Dyson in his new book Many Colored Glass: Reflections on the Place of Life in the Universe, published on Wednesday.

He pours scorn on "the holy brotherhood of climate model experts and the crowd of deluded citizens who believe the numbers predicted by the computer models".

"I have studied the climate models and I know what they can do. The models solve the equations of fluid dynamics, and they do a very good job of describing the fluid motions of the atmosphere and the oceans. They do a very poor job of describing the clouds, the dust, the chemistry, and the biology of fields and farms and forests," writes Dyson.

Biomass holds the key to carbon, he writes - leaving us to infer that he thinks the human contribution is negligible. Overall, Dyson issues a plea for more scientific research into the behaviour of the planet's biomass.

"Many of the basic processes of planetary ecology are poorly understood. They must be better understood before we can reach an accurate diagnosis of the present condition of our planet," he says.

"We do not know whether intelligent land management could increase the growth of the topsoil reservoir by four billion tons of carbon per year, the amount needed to stop the increase of carbon dioxide in the atmosphere. All we can say for sure is that this is a theoretical possibility and ought to be seriously explored."

That's the first heresy - and it's not the first time he's made it. For several years, Dyson has argued that the carbon religion is self-indulgent, when there are more urgent, fixable problems to face:

"I'm not saying the warming doesn't cause problems, obviously it does," he told students two years ago. "Obviously we should be trying to understand it. I'm saying that the problems are being grossly exaggerated. They take away money and attention from other problems that are much more urgent and important. Poverty, infectious diseases, public education, and public health. Not to mention the preservation of living creatures on land and in the oceans."

The second heresy is that "warming" might not be such a bad thing.

"If we could choose between the climate of today with a dry Sahara and the climate of 6,000 years ago with a wet Sahara, should we prefer the climate of today? My second heresy answers yes to the first question and no to the second. It says that the warm climate of 6,000 years ago with the wet Sahara is to be preferred, and that increasing carbon dioxide in the atmosphere may help to bring it back. I am not saying that this heresy is true. I am only saying that it will not do us any harm to think about it."

The third heresy, you can read for yourselves here. It's not such a heresy as the other two, but how long those remain heresies is a moot point. Dyson can expect another round of crucifixion with the predictable chorus that he's not a climate "scientist".

His contention, that the models aren't really science when they're programmed to produce the expected results, will no doubt be overlooked. ®