Last month, I was fortunate to hear Phillip Adams’ ABC Radio interview with Dr James Hansen, the US scientist who has done so much to awaken the world to the fact that our climate is already changing and that it will change catastrophically if we don’t very quickly stop dumping carbon dioxide and other greenhouse gases into the atmosphere.

Hansen is a physical scientist, which is to say that he studies phenomena that would go on even if human beings didn’t exist: ice melts when the ambient temperature rises above 0oC; when objects that contain carbon burn, carbon dioxide is released; the Earth’s surface temperature is dependent, among other things, on the gases that make up its atmosphere.

Yet one of the themes of the interview was the attacks on Hansen for what he has said. How can that be? If you dispute Hansen’s warnings about global warming, then you have to be one of two things: another scientist who has sufficient evidence and a plausible theory to contradict what Hansen argues (no one has come forward who fits that description); or a dupe of coal and oil corporations and similar polluters, whose owners figure they’ll be rich enough to get by even if most of the rest of the human race starves or drowns. The big polluters spend a lot of money trying to confuse the public about climate change. A strategy for countering climate change needs to take account of that reality.

Hansen’s expertise in the science of global temperature, his clear warning that we have to do something to reverse the build-up of greenhouse gases in the atmosphere, doesn’t mean that his suggestions for how to do this have the same validity. Part of what Hansen advocates as a way of countering greenhouse gas build-up is an increased use of nuclear power. Hansen himself would undoubtedly acknowledge that there are other equally qualified scientists, who agree about the need to combat climate change, but who think that nuclear power is not the way to do it, because of the dangers associated with that technology.

A political policy that ignores scientific realities is headed for disaster. But agreement on scientific knowledge doesn’t dictate that there is a single scientific position on how to deal with a problem. Edward Teller, honoured as the “father of the H-bomb” by US imperialism, based his work on the theories of Albert Einstein, who after World War II published a well-known essay on the need for socialism. Two scientists who were equally convinced of the same physical science principles had quite different political outlooks. That is normal.

So, in looking at how to deal with climate change, we need to keep in mind the relation between what is scientifically sound and what is socially possible. That we need to reduce the carbon dioxide level in the atmosphere is a scientific fact. How to do that is a political question that involves social change. The mistake made by Hansen (and also by his scientist opponents if they confine themselves only to questions such as how likely a nuclear reactor is to melt down) is to assume that capitalist societies decide such matters on the basis of what scientific opinion says is best for the humanity. They don’t. They decide them on the basis of what is best – often in the very short term – for those who dominate economic life.

In terms of what actually happens, it doesn’t matter whether Hansen or his scientific opponents are correct about nuclear power. Which side presents the best scientific arguments will have only an indirect effect, by influencing public opinion and to that extent modifying what capitalist governments can get away with in serving the interests of big business.

The nonsense of climate change denial that gets run every day in the capitalist media should be a more than sufficient indicator of why science alone is not enough – why we need a mass movement that can act on the basis of science and overthrow the rotten system that threatens to make our planet uninhabitable. Only then will we be able to make really scientific decisions about how our society should operate.