TOKYO — Two centuries after the dawn of the industrial age, the world today takes its first concerted step to roll back the emission of "greenhouse gases" believed linked to climate change with the enactment of the Kyoto global-warming pact.

The agreement, negotiated in Japan's ancient capital of Kyoto in 1997 and ratified by 140 nations, calls on 35 industrialized countries to rein in the release of carbon dioxide and five other gases from the burning of oil and coal and other processes.

Its impact, however, will be limited by the absence of the United States, the world's leader in greenhouse gas emissions.

Proponents say the stakes are high: the gases are believed to trap heat in the atmosphere, contributing to rising global temperatures that are melting glaciers, raising ocean levels and threatening dramatic and potentially damaging climate change in the future.

"The tools for keeping climate change under control, such as renewable energy sources and energy efficiency measures, are developed and ready to use," said Greenpeace International official Stephanie Tunmore. "There is now a price on climate pollution and penalties for polluters. The switch to a carbon economy begins here."

Implementation of the agreement was delayed by a struggle to meet the requirement that countries accounting for 55 percent of the world's emissions ratify it. That goal was reached last year — nearly seven years after the pact had been negotiated — with Russia's approval.

The Clinton administration signed the protocol in 1997, but the U.S. Senate refused to ratify it, citing potential damage to the U.S. economy and insisting that it also cover countries with fast-growing economies such as China and India.

"We have been calling on the United States to join. But the country that is the world's biggest emitter has not joined yet, and that is regrettable," Japan's top government spokesman, Chief Cabinet Secretary Hiroyuki Hosoda, told reporters.

In Japan, the host to the 1997 conference and a tireless supporter of the pact, the enactment — at midnight New York time — was being met with a mixture of pride and mounting worry that the world's second-largest economy is unprepared to meet its emission reduction targets.

Under Kyoto, the targets vary by region: The European Union is committed to cutting emissions to 8 percent below 1990 levels by 2012; the United States agreed to a 7 percent reduction before President Bush denounced the pact in 2001.