Dr. Nigel Sizer serves as the executive director of the Preventing Pandemics at the Source initiative with Dalberg Catalyst. He served for two years as President of Rainforest Alliance until January 2018. He helped lead the successful merger with the leading Dutch-based non-profit UTZ and following the merger he served as Chief Program Officer. He also advises corporate and nonprofit leaders.

Previously, as Global Director of the Forests Program at the World Resources Institute, Nigel led a hundred-person plus team across Africa, Asia, and Latin America, conceived and launched path-breaking partnerships including the award-winning Global Forest Watch and the Global Restoration Initiative.

Nigel also served as Vice President for Asia-Pacific with Rare, where he developed grassroots efforts to link impoverished communities in Indonesia to global carbon markets and pioneered community-based fisheries and marine protected areas efforts. In 2008, he served as lead advisor on climate change and energy issues in Asia to former US President Bill Clinton and the Clinton Global Initiative. He has also worked with the United Nations Environment Program in Nairobi and established The Nature Conservancy’s Asia-Pacific Forest Program. He founded and co-chaired The Forests Dialogue, which recently celebrated 20 years of progress, and helped establish and lead the Asia Forest Partnership.

A globally recognized authority on forests, ecology, climate change and development policy, Nigel holds Bachelors, Masters, and Doctoral degrees in natural sciences and tropical forest ecology from the University of Cambridge. He has lived and worked in Brazil, Kenya, and Indonesia. He has served on numerous boards and advisory groups including Natural State, Tree Global, the Tropical Forest Alliance, the Rainforest Foundation, the Amazon Alliance, the Global Forest Foundation, and the Andean Center for Sustainable Development. He has raised hundreds of millions of dollars in the course of his career. He helped inspire future leaders as an adjunct professor of nonprofit administration at Baruch College, City University of New York.  Nigel has received numerous awards including the Henry Arnold Conservation Fellowship from the Mulago Foundation and the United Nations Secretary General’s Big Data Challenge prize. He has been a frequent commentator on environment and development issues for the BBC, CNN, Al Jazeera, and many other media outlets. He now lives in the Lower Hudson Valley, New York, with his family, growing fruits and vegatables, beekeeping and helping to restore the local landscape.