The effects of climate change have become a solid reality that cannot be ignored for human life on Earth. Europe's shifting climate landscape sees a surge in legal battles, highlighting the deepening understanding of the link between environmental well-being and human rights.  This paper analyses the legal framework of so-called climate litigation, where organisations and interest groups litigate a lack of climate action on the part of governments, and its implications for and application to the Defence and Security sector. Indeed, due to the increasing number of legal challenges against governments and institutions for their inaction on climate change, there has been a growing awareness of their role in protecting citizens from increasingly frequent climate events. This awareness has impacted all areas of public governance, including defence. In fact, even the defence sector, faced with this worrying reality, has had to change itself and its practices to comply with the legal framework, which is composed not only of laws but also of judgments that are increasingly openly determining how the state and institutions have a duty to protect their citizens, through comprehensive action, from the reality of climate change.