Nigel stumbled into climate change policy in 1998 when he was appointed senior policy adviser to the U.S. chief Kyoto negotiator, Frank E. Loy.  While the opportunity first seemed unrelated to Nigel's training (business and financial law), interests (international security and development) and family background (childhood spent partly in Africa, European parents), he soon realized that solving the climate problem would require unprecedented international cooperation, as well as new laws, business models and financial markets.

In the late 1990's, Nigel became a leading architect of the Clinton Administration's diplomatic strategy on climate change.  In late 2000, he played a pivotal role in crafting an international compromise that would become the basis for the final rules for the Kyoto agreement.  Nigel stayed at the State Department for the first year of the Bush administration to help Secretary of State Colin Powell make the case for revising the Kyoto treaty rather than rejecting it.  While that effort proved unsuccessful, it earned him a reputation for bipartisanship and courage.  In both U.S. administrations he worked closely with senior officials in the White House, Congress and key federal agencies, and negotiating internationally with leading ministers and ambassadors from the world's major economies.

At the time he resigned from government service in 2002, Nigel was deputy head of the U.S. climate change negotiating team and deputy assistant secretary of state for oceans, environment and science.  In the latter role he had responsibility for all aspects of U.S. environmental foreign policy and played a significant role in designing major initiatives to conserve the Congo Basin, fight illegal logging in Asia and ban the most hazardous toxic substances globally.  During this period he was the youngest member of the State Department’s senior management team and received numerous awards for superior government service.

Since leaving government, Nigel has been active in U.S. politics and domestic environmental policy.  In 2004, the co-founded and directed a political action committee to support environmentally-minded candidates for federal office.  In 2008, he served as a senior adviser on climate change to the Obama-Biden campaign and to its transition team, frequently representing their interests in high level private meetings with the world’s leading governments.

Previously, Nigel served as vice president of The Nature Conservancy, the world's largest conservation group.  At TNC, he oversaw 200 policy staff working in 30 countries around the world and was accountable for securing more than $200 million annually in government funding.  Nigel spearheaded the creation of the Forest Carbon Partnership Facility, a $300 million public-private partnership with the World Bank to use carbon finance to encourage developing nations to reduce greenhouse gas emissions attributable to deforestation.

Along the way, Nigel has held climate and foreign policy research positions at leading U.S. think tanks, including the Brookings Institution and the Council on Foreign Relations.  He is currently a visiting scholar at Resources for the Future, a Senior Transatlantic Fellow at the German Marshall Fund of the United States and a non-resident scholar at Brookings.

Early in his career, Nigel was an international lawyer at the U.S. State Department, a capital markets attorney at Sullivan & Cromwell in New York, and a lecturer at Georgetown University.  He is a graduate of Harvard Law School, where he completed his degree with honors and received awards for his international law scholarship.