WASHINGTON - It was touted as a collection of thousands of scientists debunking global warming. So was that Perry Mason on the list? And John Grisham? What about that Spice Girl?

The petition with 15,000 signatures surfaced shortly before the April 22 Earth Day and quickly became music to global warming's critics. They highlighted it in news releases, at congressional hearings, even on the Senate floor.

The work of a chemist at a small research institute in Oregon, the petition of scientists - and some nonscientists, it turned out - has become the center of the latest furor in a contentious debate over whether human activity is changing the earth's climate.

Arthur Robinson, a physical chemist from Cave Junction, Ore., who circulated the petition by mail among scientists, said questionable names were added to the petition by pranksters.

The petition urges rejection of the accord signed last year in Kyoto, Japan, which sets procedures for dramatically lowering carbon dioxide emissions - the principal greenhouse gas. The petition maintains the growth of carbon-dioxide emissions, in fact, may be beneficial to plants and humans.

While the petition has been portrayed by global-warming skeptics as authoritative evidence that many scientists reject the catastrophic scenario of global climate change, Robinson acknowledged that little attempt was done to verify credentials of those who responded.

Several environmental groups questioned dozens of the names: "Perry S. Mason" (the fictitious lawyer?), "Michael J. Fox" (the actor?), "Robert C. Byrd" (the senator?), "John C. Grisham" (the lawyer-author?). And then there's the Spice Girl, a k a. Geraldine Halliwell: The petition listed "Dr. Geri Halliwell" and "Dr. Halliwell."

Asked about the pop singer, Robinson said he was duped. The returned petition, one of thousands of mailings he sent out, identified her as having a degree in microbiology and living in Boston. "It's fake," he said.

"When we're getting thousands of signatures there's no way of filtering out a fake," Robinson, 56, said in a telephone interview from Oregon.

Robinson, who acknowledges he has done no direct research into global warming, said the petition includes thousands of people "qualified to speak on this subject" including biochemists, geophysicists and climatologists.