Though adopted by all parties to the COP 21 more than two years ago the Paris Agreement faces serious hurdles, the least important being not the hostile position taken by the new American administration.

From the start it has been acknowledged that the total of commitments by countries for 2030 is far from setting the world economy on the trajectory consistent with the long-term target of limiting global warming to 2°C. Even before the adoption of the Paris Agreement, the vast majority of economists warned that the implementation a market mechanism is required in order to go beyond the bottom-up approach of the INDCs which obviously favors a free-riding behavior by Parties to the Convention.

The paper first presents a comprehensive assessment of the pledges by the countries (INDCs) and where they fail. It then develops and justifies a market mechanism based on the trade of quotas, with a rule of allocation weighting feasibility on the short run and equity on the long run, and gives the results of a simulation for the year 2030 showing which countries are respectively the potential sellers and the potential buyers, and what would be the financial size of the market.

A specific application is devoted to Tunisia which, though a small country and a very small GHG emitter, showed a great ambition in its conditional contribution