In his early 20s, John-O Niles spent three years in Nigeria and Cameroon conserving endangered primates and their habitats. In his late 20s, as a graduate student, he published numerous peer-reviewed articles and books, including a graduate textbook on climate science and policy. In 2003, he became the first director of the Climate, Community & Biodiversity Alliance, one of the leading global sustainable development standards. In 2006, he was named the first Science and Technical Advisor for the Coalition of Rainforest Nations (CfRN), the block of nations that brought reducing emissions from deforestation in developing countries (REDD+) to the forefront of climate change diplomacy and action. From 2008 to 2012, he was Director of The Tropical Forest Group, and led a dozen affiliates in policy work, humanitarian conservation, forest measurements and greenhouse gas accounting. In 2012, he became Director of the Forest and Climate Program for WWF US. He also lectures at the University of California, San Diego in global carbon science and policy.