London ? For anyone trying to isolate the real issues dividing leaders at the Group of Eight summit convening today, the words between the brackets tell it all.

Only hours before the summit’s opening in Gleneagles, Scotland, negotiators representing the world’s leading industrialized nations had yet to resolve major differences over a joint communique proposing solutions to the world’s most pressing problems.

The Live 8 concerts July 2 focused unprecedented public attention on the G-8 summit, specifically its agenda for African aid. But so far, negotiators have been unable to word the communique in a way that satisfies everyone, especially President Bush. And until they do, unacceptable wording must remain in brackets, awaiting further negotiation – which could continue until the final hours of the summit on Friday.

British Prime Minister Tony Blair, the summit’s host, has placed global climate change and aid to Africa at the top of the agenda. But he has found that identifying major world problems is far easier than coming up with solutions that leaders can agree on.

The ability to remove the brackets and reach consensus will be the measure of the summit’s success, said Britain’s chancellor of the exchequer, Gordon Brown.

“What Britain says is one thing. What we can persuade the rest of the world to do together is what we will get as the outcome of Gleneagles,” he told the BBC on Tuesday.

Police officers walk by the flags of the G8 leaders in front of the Gleneagles Hotel near Auchterarder, Scotland. Scottish police on Tuesday promised zero tolerance for troublemakers at protests planned to coincide with the opening of the summit of leaders of the G8 group of wealthy nations, which begins today.

Many brackets remain, and time is running out, according to Sir Michael Jay, Britain’s chief negotiator.

“The idea is to have an action plan but also to have agreements on the reasons for an action plan,” he told reporters Monday. “What we’re trying to achieve is the agreement on the importance of the issue, agreement on the importance to act on the issue, agreement on what that action should be.”

On topics as amorphous and controversial as global climate change, the use of seemingly innocuous phrases such as “global warming” can be subject to intense negotiation. The United States has reportedly opposed references to the phrase and has sought to alter wording about the causes and cures for climate change.

Although other G-8 leaders support plans for mandatory cuts in the so-called “greenhouse gases” and carbon emissions blamed for global warming, Bush contends that the better solution is voluntary cutbacks and a focus on developing cleaner technologies. Mandatory emissions cuts, he says, would devastate the economy of the United States, which constitutes only 5 percent of the world’s population but produces a quarter of the world’s energy-related carbon emissions.

There is no guarantee of success, Jay said.

“There have been quite intense negotiations,” he said. “The issue of how you characterize the science has always been the most difficult issue. In other ways, the important issue is going to be: Can agreement be reached on a way forward?”