This chapter introduces the reader to the physics of climate change and its impacts past, present and future, including: temperature rise, sea level rise, snow and glacier retreat, permafrost thaw, ocean acidification, ocean ecosystem impacts, as well as impacts on freshwater resources, terrestrial ecosystems and the biosphere, pollination and pests, animals and extreme weather events. This latter is wide-ranging covering: cyclones, flood risk and extreme rainfall, drought and fire risk. This chapter also examines impacts on food production, agriculture, fishing, aquaculture, forests, human health, surface air pollution, socio-economics, poverty and living standards, infrastructure, cities and the built environment. One of the primary aims of this chapter is to as far as possible summarise and explain the science behind the Intergovernmental Panel for Climate Change’s Assessment Reports, which run to many thousands of words covering all aspects of climate change and global warming and based on the work of hundreds of scientists, including projections of impacts stretching to the end of the twenty-first century and beyond.