WASHINGTON — Leaders of the Group of 8 leading industrial nations on Tuesday set a goal of cutting global emissions of greenhouse gases in half by 2050 and said that all major economies should join the effort.

But the joint statement from the G-8 meeting in Japan didn't say what year would be the baseline for the 50 percent cut, and it didn't impose any tough midterm reduction requirements that would require nations to act quickly.

The White House called the agreement progress. Dan Price, President Bush's deputy national security adviser for international economic affairs, said that the statement showed the G-8 countries agreed "that all major economies, developed and developing, must commit to meaningful midterm mitigation actions" and that those actions must be part of a new international agreement now being negotiated that would take effect in 2012.

Price said that the G-8 leaders also had committed to spending $10 billion on research and development of clean energy technologies.

The G-8 members are the United States, Japan, Russia, Germany, France, Britain, Canada and Italy.

The statement said the goal should be accomplished "within a time frame that should be compatible with economic growth and energy security."

Sen. Barbara Boxer, D-Calif., the chair of the Senate Environment and Public Works Committee, said the G-8 statement was no big step forward.

"The Bush administration said they would agree to a goal of 50 percent — but, but, but. It's a goal, it's not a mandate. But if China and India don't act, we don't do anything," Boxer said. "It's saying something to get the heat off, but it's doing nothing and it's hiding behind India and China, which is their latest way."