Why most Social Cost of Carbon estimates are bullshit

The estimation of SCC is fraught with uncertainties in estimating (a) the emissions paths that are likely in the future as that depends on future policy and technology, (b) the parameters that map emissions to climate change, (c) the translation of climate change into physical and economic damage, (d) the choice of the appropriate discount rate. Changing some of these assumptions or introducing something like ecosystem services that are not substitutable with man-made capital changes the policy recommendations radically.