W. STERK, H.-J. LUHMANN, F. MERSMANN| HOW MUCH IS 100 BILLION US DOLLARS internationally under the roof of the UNFCCC. The ex­ample of the EU ETS shows that if revenues are collected nationally, probably only a very minor share will be allo­cated to international climate finance. Finally, one should also look beyond 2020. This analysis has strongly emphasised the substantial revenue poten­tial of auctioning emission allowances. However, as caps are further tightened the amount of allowances that are available for auction will decrease. In the short and medium term this may be compensated by the corre­sponding increase of the carbon price but in the long term the revenue potential is likely to decline. However, adaptation needs and damages from climate change impacts will substantially increase over time. Attention should therefore also be paid to tapping new sources of finance that are not tied to the dwindling supply of emis­sion allowances. Prime candidates appear to be financial instruments connected to financial markets such as fi­nancial transaction taxes and the use of special draw­ing rights. At the moment, the political resistance to in­troducing such instruments is substantial but over time the growing financing needs related to climate change and other global concerns may leave no other option. 12