It seems important to me to keep two things in our head at the same time on climate change: 1) the overwhelming evidence suggests grave risks (however hard they are to model accurately) of future planetary distress because of too much CO2; and 2) how we try to rectify this is a separate question and can lead to several different answers.

The Dish has aired the cap-and-trade vs carbon-tax debate exhaustively this past year. I have to say that, as the debate has unfolded, my own inclination to support a small and gradually increasing carbon/gas tax has strengthened. Here is one of the founding fathers of climate change science, James Hansen, the director of Nasa’s Goddard Institute for Space Studies, boycotting Copenhagen over this very question:

“The fundamental problem is that fossil fuels are the cheapest form of energy. As long as they are, they are going to be used,” he said. “It’s remarkable. They refuse to recognise and address the fundamental problem and the obvious solution.”

He dismisses government announcements of national targets for greenhouse gas emissions as promises that will not be kept, noting that even Japan missed its goals under the Kyoto Protocol.

He said that it would be better for the summit to fail rather than reach the type of cap and trade-based system envisaged.

“If they sign on to anything like they are talking about then it’s definitely counter-productive. Any time you start down that path, it’s time wasted. We would do better taking a year time-out and figuring out a better path.”

Dr Hansen, an adjunct professor at Columbia University’s Earth Institute in New York, argued that the only effective way to control global warming was to institute an increasing “carbon tax”, not “cap and trade”.

“We are going to have to move beyond fossil fuels at some point. Why continue to stretch it out longer?” he said. “The only way we can do that is by putting a price on carbon emissions. The business community and the public need to understand that there will be a gradually increasing price on carbon emissions.”

He proposes that the “carbon tax” start at the equivalent of about $1 per gallon of petrol but rise in future years. The tax revenues should be returned directly to the public in the form a dividend, he said.

He added that the world must be prepared to abandon coal unless its emissions are captured and embrace a new generation of nuclear power.

Why is this country's political system unable even to contemplate the most obvious, cleanest, simplest response to this emerging problem?