Nigel Sizer joined The Nature Conservancy (TNC) in January, 2001. He serves as Director of the Forests Program for the Asia Pacific Division. He is based in Bogor, Indonesia, and is charged with developing new projects to abate threats to forests throughout Asia and the Pacific. These responsibilities include serving as Chief of Party and Coordinator for the Alliance to Promote Certification and Combat Illegal Logging in Indonesia. This is a partnership lead by TNC and WWF-Indonesia with about 30 other partners (most from the private sector) and majority funding from the US Agency for International Development. He also advises on TNC-wide forest conservation initiatives.

Prior to joining TNC, Dr Sizer worked with the prestigious environment policy think tank, World Resources Institute, based in Washington DC, for eight years. At WRI he headed up the group of experts working on forest issues all over the world, including in the Amazon and Andean countries, Congo Basin, Indonesia, Burma, Canada, and Russia. There he published many reports including Profit Without Plunder: Reaping the Revenue from Guyana's Tropical Forests without Destroying Them, Backs to the Wall in Suriname: Forest Policy in a Country in Crisis, and Opportunities to Save and Sustainably Use the World's Forests through International Cooperation. He helped to create Global Forest Watch, a worldwide network to monitor the state of forests that now has chapters all over the world.

He has written widely about global forest issues, including for The New York Times, The Washington Post, The International Herald Tribune, The Guardian, The Journal of Commerce, The Jakarta Post and The Toronto Star.

Before working with WRI, Dr Sizer was affiliated with the Department of Tropical Forestry at the Brazilian National Institution of Amazonian Studies in Manaus. He spent three years as a field scientist in the Brazilian Amazon for the Smithsonian Institution and the University of Cambridge, England.

Dr. Sizer gained First Class Honors Bachelors and Master of Arts degrees in Natural Sciences from King’s College, University of Cambridge, where he was awarded various prizes and scholarships. He received his Ph.D. in Tropical Forest Ecology from the same institution.

He has served on the boards of The Rainforest Foundation, the Amazon Alliance, the Global Forest Foundation, and the Andean Center for Sustainable Development. He currently co-chairs The Forests Dialogue, a global forum for leaders from industry, environmental groups, labor and private forest owners to address conflicts related to forest resources. He is on the steering committee of the Forests Integrity Network created by Transparency International.