This Technical Summary synthesizes the key evidence and messages of GEO-6. Chapter 1 sets out the context and methodological approach of the GEO-6 assessment. It is followed by chapters that: i) discuss the five drivers affecting the health of the planet: trends in human population, combined with economic development; growth of consumption; rapid urbanization; accelerating technological innovation; and climate change (Chapter 2); ii) review the impacts of broad systemic activities (called cross-cutting issues in the GEO-6) and the health, equity and economic dimensions of these impacts (Chapter 3); collectively providing evidence that the planet is becoming increasingly unhealthy;. iii) review the literature and undertake case studies on policy implementation to show how policies are struggling to keep up with the rate and scale of planetary degradation (Chapter 4); iv) assess the literature to demonstrate that there is a case to be made for transformative change linking the health of the planet to human health (Chapter 5) and v) examine the changing role of knowledge and data for a healthy planet (Chapter 6).