Philip Clapp, environmental activist with Pew Trust

AMSTERDAM - Philip E. Clapp, a veteran environmental activist who helped bring high-powered business lobbying to such issues as climate change, has died in Amsterdam, the Pew Charitable Trust said yesterday. He was 54.

Mr. Clapp, a resident of Washington, D.C., died Wednesday while visiting the Dutch capital, according to a Pew statement. The organization refused to provide details on a cause of death.

Pew's president, Rebecca Rimel, praised Mr. Clapp as a master of framing complex scientific issues in a way that resonates with policy makers and the public.

"Phil was a true visionary about environmental issues, their consequences, and the most effective means to address them," she said.

Mr. Clapp worked for more than a decade on Capitol Hill after graduating from Harvard.

He was a Democratic staff member of the US House Budget Committee, where he directed the environmental task force.

He also headed the legislative practice of a large Washington law firm and was a consultant on mergers and acquisitions to investment banking firms.

In 1994, he founded and directed the National Environmental Trust, a nonprofit public relations firm funded by large foundations to campaign for water and air quality, endangered species, and the protection of forests and oceans.

Pew said the firm is credited with playing a key role in adopting a broad range of US environmental policies, from the landmark Safe Drinking Water Act Amendments of 1996 to the passage of the Magnuson-Stevens Fishery Conservation and Management Act of 2006.

He was an early and vocal advocate on climate change issues and a promoter of the international agreement concluded in 1997 in Kyoto, Japan.

Mr. Clapp continued to attend subsequent global warming talks even after the US Congress did not ratify the Kyoto accord.

Mr. Clapp became deputy managing director of the Pew Charitable Trust when the two groups merged in January.