Is the concept of “supplementarity” or a similar concept defined within any multilateral environmental agreement (MEA) regime or other treaty regime?
We have asked four different international law experts the above query.
To their knowledge, no other treaty exists which has a similar concept to the UNFCCC notion of countries being able to “supplement” their domestic reductions with international measures such as emissions trading. CO2’s role as a global pollutant (rather than one with local or regional impacts) would seem to make it unique in this regard.
While we cannot be definitive in stating that the concept does not exist elsewhere, we strongly believe this to be the case.