Prior to joining Environmental Defense Fund, Krupp spent several years in private law practice in New Haven, Connecticut in several firms: Cooper, Whitney, Cochran & Krupp (1984); partner, Albis & Krupp (1978–1984). During that time he also was founder and general counsel for the Connecticut Fund for the Environment (1978–1984), a leading state environmental group.
Since 1984, when he became president of Environmental Defense Fund, he has been influential in developing many innovative market-based solutions, including the acid rain reduction plan in the 1990 Clean Air Act, and the U.S. proposal to achieve least-cost greenhouse gas reductions in the Kyoto Protocol.
According to the Form 990 filed by Environmental Defense Fund with the Internal Revenue Service as required by law, in 2004 he earned $357,057 in salary and $51,113 in other compensation as president.
Krupp serves on the board of the H. John Heinz III Center for Science, Economics and the Environment, the John F. Kennedy School of Government Environment Council, the Nicholas Institute for Environmental Policy Solutions, and the Leadership Council of the Yale School of Forestry and Environmental Studies. He has served on the President’s Advisory Committee on Trade Policy and Negotiations for Presidents Bill Clinton and George W. Bush.
He is the recipient of the 1999 Keystone Leadership in Environment Award, and the 2002 Champion Award from the Women’s Council on Energy and the Environment.
In March 2008, Earth: The Sequel, the book he wrote with journalist Miriam Horn, was released. It highlights innovators and the technology they are creating to fight global warming.