Before the role of insurance in the global fight against climate change can be explored, it is necessary to consider some key concepts relating to climate change, the science behind it, and the efforts of the international community to respond to the threat of climate change. This chapter sets the scene for the discussion in the following chapters and provides an overview of the key literature and international treaties on climate change. Section 2.1 defines ‘climate’ and ‘climate change.’ Section 2.2 sets out the main evidence-based findings of the IPCC on the causes of climate change, climate change impacts, and its projections for different GHG emission reduction pathways and their temperature impacts. Section 2.3 outlines the international treaties – the most prominent of which is the Paris Agreement – that have sought to address climate change, and how these treaties have been implemented in the UK and the EU. Section 2.4 positions climate action as a subset of environmental protection measures and explores the relationship between climate action, climate resilient development approaches, sustainability, and ‘ESG.’