This paper presents the impact on growth of a massive disinvestment in the fossil fuel sector based on macroeconomic tools such as the Green Solow Model for the long term and IS/LM and WS/PS for the short and medium term. In the current theme of climate change, this work wishes to bring an economic point of view to environmental and social problems, and in particular to derive the impact of the disinvestment movement of fossil energies. It is found that, under certain hypotheses, the effect of this movement is beneficial in the long term on growth and despite some questioning about the possibility of recession in the short and medium term, the analysis of Saudi Arabia and the Dutch Disease gives interesting results for the consequences of a decrease in the use of fossil fuels and advice on diversification for countries dependent on fossil fuels.