Professor May has an undergraduate degree in human ecology from The Evergreen State College (1974), and a master’s in city and regional planning (1979) and doctorate in natural resource economics (1986) from Cornell University.

He is a professor at CPDA/UFRRJ and at the Graduate Program in Public Policies, Strategies, and Development in the UFRJ Department of Economics.

He is a researcher at the Brazilian National Institute of Science and Technology in Public Policies, Strategies, and Development (INCT-PPED).

He served as president of the International Society for Ecological Economics (ISEE, 2008–2009) and the Brazilian Society of Ecological Economics (ECOECO, 2014–2017), as well as Deputy Director of OSCIP Amigos da Terra-Amazônia Brasileira (AdT, 2005–2012).

He works with the UNEP/UN TEEB (The Economics of Ecosystems and Biodiversity) program.

His experience in the area of natural resources policy and economics mainly focuses on the following topics: biodiversity valuation and payment for ecosystem services (PES), reducing deforestation emissions and forest degradation (REDD+), clean development mechanisms (CDM) and the voluntary forest carbon market, agricultural trade and the environment, sustainability indicators, socio-environmental certification, agroecology and sustainable forest management, financing of conservation units, non-timber forest products, river basin management, and agroforestry systems.