A Stern response
Thomas Sterner and U. Martin Persson focus on the criticism raised by William Nordhaus (who I've mentioned before) on Stern's assumption of a near-zero discount rate when considering the future costs of long-term climate change (this is a common economist's device based on the principle that a pound today is preferred to a pound tomorrow). I've not been convinced by Nordhaus' argument - while a significant discount rate is certainly applicable in cold financial decisions, it's less so when considering wider social criteria. If someone argues that we shouldn't invest now to try and reduce potentially catastrophic climate change because the current costs of doing so outweigh the discounted future costs of not doing so, then there's an obvious question to ask them: what generation of your own descendents are you willing to sacrifice for your own current comfort? By revealed preference, that should give some idea of their real social discount rate.
Anyway, Sterner and Persson use a few well established bits of economic theory to argue that, even if one takes a higher discount rate than Stern, the same conclusions are still justified.
We argue that nonmarket damages from climate change are probably underestimated and that future scarcities that will be induced by the changing composition of the economy and climate change should lead to rising relative prices for certain goods and services, raising the estimated damage of climate change and counteracting the effect of discounting.
The moderately technical paper can be downloaded as a PDF here.