The Master of Environmental Studies (MES) program at the University of Pennsylvania helps you translate your passion for the environment into a fulfilling career. Our program offers you a rigorous academic grounding in environmental science and exceptional opportunities to conduct research in the field. In addition, you gain the professional networks and individualized professional development you need to excel in your work, whether as a researcher, policy advocate, teacher or business executive. More than 50 percent of the people in the world live in urban areas and this number is expected to increase dramatically in the coming decades. Some experts say that in 100 years, all of the world's population will live in cities. In the United States and around the world, critical issues in the urban environment include planning and designing systems for clean air and water, ensuring equity for the poor, transportation, environmental health, brownfield remediation, community development, physical infrastructure and food security.