This document discusses key economic challenges over the next 50 years based on analysis using economic models. It identifies six major trends: 1) shifting patterns of economic growth; 2) rising global economic interdependence; 3) increasing global environmental costs; 4) continued increases in earning inequalities; 5) substantial fiscal challenges; and 6) medium-term risks of rising current account imbalances. It examines the consequences of these trends and discusses policies to support growth, limit rises in inequality, and address rising climate change costs on both national and international levels through policies like carbon pricing, education investment, and tax coordination.