In his State of the Union message  to Congress in January, President Bush acknowledged, in the clearest terms he has used to date, the urgent need for action to address global climate change. But the address contained no major shifts in his Administration's climate policy.

The President is firmly opposed to mandatory curbs on carbon dioxide emissions. Instead, he favors technological innovations and voluntary approaches to reducing the greenhouse gases responsible for global warming.

But can voluntary programs cut emissions enough to make a difference? That's the question addressed in a new book by the U.S. think tank, Resources for the Future.

The book is called: Reality Check: The Nature and Performance of Voluntary Environmental Programs in the U.S., Europe and Japan. From among the thousands of local, state and national programs in these countries, the authors focus on seven with records dating back to the early 1990s.

They range from a German cement industry plan for voluntary reduction of fuel consumption, to a powerful Japanese business association plan that cuts across energy sectors to stabilize the country's greenhouse gas emissions by 2010.

The editors also include a U.S. plan aimed at reporting the significant release of certain toxic chemicals. The other six studies in Reality Check focus on voluntary initiatives related to energy and greenhouse gas issues.

Co-editor William Pizer says the report's assessment of these voluntary initiatives, measured in the percentage reduction in greenhouse gases, ranged widely in terms of program effectiveness. "The low point is the German cement industry where the estimate is zero. The high point is the U.S. 33/50 program where the estimate is closer to 30 percent."

The U.S. program gets its name from its goal to reduce the release of certain high priority chemicals below 1988 levels by 33 percent by 1992 and 50 percent by 1995.

Pizer says people were worried people about the safety of their local environment and pressed for reductions. "Whereas climate change is a global issue and it involves a problem that is further off in the distance for a lot of people."

Pizer says when energy or greenhouse gas emissions programs are analyzed separately, they average only a five percent reduction in emissions. "If you are really serious about changing behavior then voluntary programs are not going to be the right tool."

Pizer says tax relief and other financial incentives can encourage emissions reductions, but not that much.

Programs like the Danish Energy Efficiency Agreement and the U.K. Climate Agreements have the higher reductions and offered tax exemptions. But Pizer finds 3-5 percent effects in other programs that didn't have huge financial incentives.

While stabilizing the climate will require much more aggressive tools than voluntary reductions, Pizer says initial steps like emissions tracking give major polluters a framework for what later may become a government mandate. "I think that people get used to what a regulatory approach is likely going to require and are therefore less frightened by it when the regulation comes down the pike."

Reality Check Co-editor Richard Morganstern says voluntary actions taken by U.S. private industry and individual states to curb emissions have begun to make their way into proposed legislation. "In several of the bills on Capitol Hill now, there are provisions for credit for early emissions reductions."

Samuel Thernstrom does not think these efforts go far enough even as government mandates. In a policy paper for the American Enterprise Institute,  a Washington-based research group, he calls for new, clean and affordable energy technologies that can stabilize the climate over the long term. "What we need to be doing is not working on what I call 'evolutionary technologies' such as hybrid cars that produce slight improvements in fuel efficiency, we need to be working on the 'revolutionary technologies' such as hydrogen fuel cell cars, which are true zero emission cars."

Thernstrom believes the development and deployment of these radical strategies will be more effective in the long run against global warming than all the emission-curb programs now pending in the U.S. Congress.