In this context: The 2-degree-objective has been contested of course. Any number is always arbitrary to some extent (why not 2.1 or 1.9 degrees?). Is there any mechanism in the model that would justify a clear threshold level? Does the model predict that a rise about x degrees would lead to something qualitatively different than any rise in average temperature that remains below these x degrees? Are there tipping points in the model, points of no return? A quantitative version of the model would provide some rational for 2-degree-objectives and could come up with quantitative values for the x.

]]>A nice feature of the work by the two Hillebrands is their multi-country framework. This would allow to model “costs in the North and death in the South”. One would make the effects of environmental changes dependent on the current development level of a country. But I guess, one should first come up with some numbers on what it actually means that there are only costs in the North (good warning systems, we just reconstruct our houses?) vs more threatening effects in the South (fewer well-developed institutions, less well-developed health systems?). I see that this sounds more like future work than a precise comment for this specific paper.

]]>Prior literature, with fewer transfer policies in the model, do find higher degree of progressivity for the optimal tax. ]]>

Just after skimming the paper I am wondering on:

(iii) the output multiplier is positively correlated with wealth inequality

Does the research imply something on the size of multiplier with respect to income inequality? Then, I think, we could relate to the literature on the fiscal policy during recession/expansion (e.g. Auerbach, Gorodnichenko 2012).

And more interestingly, there are some cross-country estimates of multipliers and wealth inequality. One could check if the data show positive correlation, as shown in the paper.

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