Cities concentrate people, economic activity and pollution. Covering less than 5% of global land area, cities are home to more than half the Earth's human population, produce over 96% of global gross domestic product, and consume nearly 80% of energy. Join us on campus for our Discoveries Lecture Series featuring Professors Lucy Hutyra and Nathan Phillips of the Department of Earth & Environment. Hutyra and Phillips are in the midst of a National Science Foundation funded research project; studying Boston's energy and resource flows and tracking carbon as the lifeblood of Boston's urban metabolism. They will discuss two key carbon compounds and greenhouse gases, carbon dioxide (CO2) and methane (CH4), what these compounds tell us about Boston's environmental health, and opportunities for greater urban sustainability. Discoveries, a series of dynamic learning opportunities for alumni and friends, features faculty experts from the College of Arts & Sciences and is brought to you by the Boston University Alumni Association.