This document summarizes a talk given by Jane Lubchenco at the 1997 AAAS annual meeting about how the scientific community needs to adapt to meet new environmental challenges. It discusses four key points: 1) How the world is changing due to human impacts like population growth and resource use; 2) The implications of these global changes for society; 3) The role science must play in addressing challenges created by a changing world; and 4) How scientists should respond to these challenges by reexamining priorities and redirecting efforts towards more sustainable solutions. The author calls on scientists to define a new social contract to devote their skills and research towards the most pressing problems of the day in exchange for public funding.