I have been looking at this research report from ABARE on their forecasts for different scenarios of Global Warming effects and the cost Australia in terms of GDP. As someone trained in science one thing that I find striking about this is that whereas scientific estimates include some estimate of uncertainty, eg the IPCC’s estimate of the effect on AGW to 2001 of 2C and 4.5C. The forward estimates of GDP do not.
This strikes me as bizarre that no attempt to quantify the error band for GDP estimates is made particularly over such a long time frame. Even over the time period of one year forward we could expect a standard deviation of perhaps +/- 0.5% on the GDP estimates and that is probably generous. Over the 50 year time frame this error (assuming they are independent random errors) would scale to around 3.5%. Given that the differences in the outcomes between scenarios for all but the most punative carbon tax are mostly smaller than this it would tend to suggest that the model isn’t really accurate enough to distinguish between the different scenarios and instead they are quoting false precision.
Perhaps I have missed something and there is some footnote explaining this, or some standard assumption but I can see it and if so can someone please point out the relevant information. More likely I think they don’t want to admit inability of their models to clearly distinguish between different courses of action.