The effects of environmental taxes and quotas on the optimal timing of emission reductions under Choquet-Brownian uncertainty

► Taxes and non-tradable quotas for the reduction of pollution emissions are analyzed. ► The optimal adoption threshold under taxes is always larger than under quotas. ► Regulators wishing to implement cleaner technologies should prefer quotas to taxes. ► It holds also with ecological uncertainty and Choquet-Brownian ambiguity. ► More ambiguity averse regulators are more cautious in adopting such policy options.