The latest issue of Nature has a paper on climate mitigation by Rogelj et al. The issue also has a "News and Views" item by Steve Hatfield Dodds on the paper. The paper has an interesting message*: Delay in acting on mitigation has the biggest effect on the probability of achieving the 2C target, carbon taxes above $20-40 per tonne have little effect on mitigation, and carbon capture and storage (CCS) is essential. This is a message that environmentalists, business, and fossil fuel producers will like. As Steve points out, one weakness of the paper is that it is all done with the MESSAGE integrated assessment model and that is kind of a black box. In the EMF-22 modelling exercise, MESSAGE had some of the lowest carbon taxes. For a 450 ppm scenario its 2020 carbon tax was only $15. By contrast, FUND had a $260 carbon tax. So MESSAGE is an optimistic model. Other models definitely don't have this carbon tax saturation phenomenon as can be seen from our meta-analysis.
Our PhD student Hyung-Sup Lee's PhD thesis will provide a similar kind of uncertainty analysis purely on the economic side of things using that EMF-22 data.
* Pun kind of intended :)