Is common ground possible between Climatologists and Contrarians?

On the blog of Bishop Hill, a climate contrarian, the matter of consensus is raised, in the context of whether the BBC should be required always to "balance" the statement of climatologists with a counter statement from a contrarian.



The Bishop says

"What is the consensus? That carbon dioxide is a greenhouse gas? Yup. That man's activities are increasing carbon dioxide levels? Certainly. That temperatures went up at the end of the twentieth century and have not gone up since? Definitely.That human beings can affect the climate? Without a shadow of doubt. Anything else?"



My comment:

Bishop,

Let us see if we can find how much common ground is shared between the two sides in this debate, by proceeding stepwise with the science.

We agree

• that the Greenhouse Effect exists, 
• that CO2 is a Greenhouse Gas (GHG), 
• that doubling CO2 will produce an increase (eventually, when equilibrium is re-established) of ~1.2C,
• that Climate Sensitivity means that this increase will be amplified.

The extent of this amplification is all that we need to debate. You have agreed with a figure of between 1-2.5C for Climate Sensitivity  (for doubled CO2), on the basis of Forster & Gregory 2006.

Many studies put CS much higher than that, but you set this work aside since it is tainted with computer modelling. There is a debate to be had somewhere else as to whether it is reasonable to regard computer modelling as tabu, rather than a technique to be viewed with due criticality.

The possibility that a temperature rise of 2.5C is reasonably probable (in your view) should be enough to cause mankind to start a process of cutting back on all greenhouse gas emissions. The Precautionary Principle endorses such a course of action, and there are a whole slew of other gains - jobs, technological progress, reduction in air pollution, reduction in ocean acidification, blunting the effect of Peak Oil - that flow from this course of action.

I acknowledge the anxieties on your side on the effect of decarbonisation on the economy. I feel that these anxieties have been allowed to build up into a form of - dare I say it - alarmism. Not to say hysteria.

Yes, there will clearly be an impact on the profitablity of oil and coal companies but these companies have known from their inception that their product is finite, and if they have not made provision for coping with a run down in demand for their product, they have no-one but themselves to blame.

Have they?