The decision of the 45th US president on June 1, 2017, to withdraw the United States of America from the COP21 Paris agreement caused a deep change in the environmental scenarios of the global economy, which risks moving away from the virtuous path of a green economy. The major conclusion of our model is to prove the existence of infinitely many economic scenarios in which a strong commitment towards the global green economy will allow gains for each country participating in a green deal project and guarantee significant advantages with respect to a non green undesirable scenario. For this purpose, we propose a dynamical duopoly-type model–for a generic type of green (i.e. low Greenhouse Gas (GHG) emissions) technology good–based on coopetition. In our game model, we suggest coopetitive strategy profiles as solutions for a continuum of possible global economic interactions after the Paris agreement on climate change, given the 45th US president's decision to abandon the agreement itself. More specifically, we construct a game theory coopetitive model with two macro actors for our duopoly game–the United States and the group of countries that still hold to the COP21 global agreement on climate change. Our multidimensional coopetitive model naturally shows a continuum of possible global economic games–within COP21–based on cooperative paradigms and strategy designs, in order to improve the efficiency and strength of the policies enforced by the countries and in order to mitigate climate change and build a truly green global economy. Our approach shows how the actors of the game can expand the pie of their possible gains and to share those gains fairly. A limitation of our analysis concerns the chosen deterministic nature of the parameter expressing the degree of accession to COP21 agreement. A probabilistic approach would be more suitable, and this could constitute a development of plans for future research. Another limitation consists in assuming the total COP21 goal fulfillment of the countries accepting the COP21 agreement. In both cases our model could be easily generalized to overcome these drawbacks.