Robert Pindyck in “CLIMATE CHANGE POLICY: WHAT DO THE MODELS TELL US?”:
ABSTRACT: Very little. ….
One of the problems with these long range models is the use a discount rate. This rate can have large effects on the model results. This is true in many models with long planning horizons. One should be aware of this, e.g. by running different scenarios with different discount rates to see what the impact is on the solutions.
Listen also to: http://www.econtalk.org/archives/2013/08/pindyck_on_clim.html.