Svenn Jensen

With Christian Traeger.

 

We analyze how uncertainty about the sensitivity of the climate system to human emissions in optimal policy. We provide an approximate analytic formula for the uncertainty premium and calculate the premium for a full stochastic integrated assessment model.

With Christian Traeger. European Economic Review, 2014.

 

Economic growth over the coming centuries is one of the major determinants of today׳s optimal greenhouse gas mitigation policy. At the same time, long-run economic growth is highly uncertain. This paper is the first to evaluate optimal mitigation policy under long-term growth uncertainty in a stochastic integrated assessment model of climate change. The sign and magnitude of the impact depend on preference characteristics and on how damages scale with production. We explain the different mechanisms driving optimal mitigation under certain growth, under uncertain technological progress in the discounted expected utility model, and under uncertain technological progress in a more comprehensive asset pricing model based on Epstein–Zin–Weil preferences. In the latter framework, the dominating uncertainty impact has the opposite sign of a deterministic growth impact; the sign switch results from an endogenous pessimism weighting. All of our numeric scenarios use a DICE based assessment model and find a higher optimal carbon tax than the deterministic DICE base case calibration.

With Michael Hoel. Resource and Energy Economics, 2012.

 

We use a two-period model to investigate intertemporal effects of cost reductions in climate change mitigation technologies for the power sector. The effect of cost reductions for CCS depends on how carbon taxes are set. If there is no carbon tax in period 1, but an optimally set carbon tax in period 2, a CCS cost reduction may reduce early emissions. Such an innovation may therefore be more desirable than comparable cost cuts related to renewable energy. The finding rests on the incentives fossil fuel owners face. If future profitability is reduced, they speed up extraction (the ‘green paradox’), and vice versa.