Climate change has become one of the defining global challenges of our time. The warming of the planet is no longer a distant threat but an observable and measurable process that is already transforming natural systems and human life. This chapter discusses the underlying causes and consequences of climate change, paying particular attention to the interplay between natural factors and human-induced activities. While natural processes such as volcanic eruptions, solar radiation cycles, and orbital variations have always influenced the Earth’s climate, the rapid increase in greenhouse gas emissions caused by industrialization, energy production, and land-use change has accelerated global warming to unprecedented levels. The chapter explains how carbon dioxide, methane, and other gases intensify the greenhouse effect and disturb the planet’s energy balance. Using data and figures, it illustrates long-term trends in temperature rise, sea-level increase, and greenhouse gas concentrations, revealing their cumulative effects on ecosystems and societies. The text also introduces the main indicators used to monitor climate change, including surface temperature, ocean conditions, and land cover alterations. Furthermore, the chapter highlights the European Union’s approach to climate mitigation and adaptation, reflecting its policy evolution toward a sustainable, low-carbon future. By linking scientific understanding with policy frameworks, the discussion underlines that addressing climate change requires not only technological and economic adjustments but also strong political commitment and international cooperation. Ultimately, the chapter argues that climate change mitigation is not just an environmental necessity but a shared responsibility for humanity’s long-term well-being.