Even though the best time to act for the mitigation of climate change was almost thirty years ago , and even if today would still be acceptable, the fact remains that most of the action and effort that must be made to reduce greenhouse gas (GHG) emissions are postponed until tomorrow. This procrastination is not without consequences. One of them is that climate risk is not taken seriously enough and is insufficiently addressed. Inevitably, this leads to an increase in the risk of climate litigation . Indeed, civil society is becoming impatient and taking legal action challenging the lack of ambition of the States in climate matters. In two decisions in 2020 and 2021, the Conseil d'Etat -High Administrative Court- (here after the High Court or the Court)) in France had the opportunity to rule on these issues. This is the case known as “Grande Synthe”, referring to the city that filed the petition before the High Court, in an appeal for “exces de pouvoir” –exces of power -, asking the administration to take further action in the fight against climate change. The purpose of this article is to analyze the two decisions in order to identify their scope and implications?. The facts and the decision will be first presented (II). Then, we will present the main contributions of the two decisions and the scope for the future of climate litigation in Europe (III).