Beginning with a broad history of the universe, earth, life, and man, it considers the origins and rise of science and technology, before moving on to discuss the present state of the world and its/our possible futures. Humans on Earth then addresses the main challenges for social and economic development in the 21st century in the context of global change. It presents a detailed but non-technical analysis of questions relating to climate change, our dependence on fossil fuels, deforestation, loss of biodiversity, desertification, and air, water, soil, and ocean pollution, as well as problems related to overpopulation, poverty, social and economic inequalities, and conflict potential. The main emphasis is on the risks and uncertainties of the short-term future, the next 50 to 100 years, with regard to environmental degradation and the sustainability of our growth paradigm.