Finding ways of capping carbon emissions is on the agenda for this week’s G8 Summit, which begins today on the pristine Japanese island of Hokkaido. But if anything is getting capped, it’s expectations for a meaningful agreement on climate change.

A competing jumble of climate change negotiations have turned the forum itself into a debate topic as polarizing as the carbon markets and global targets being proposed. Not one, but two extra groups have joined the G8 at Hokkaido, each with the potential to reach its own set of conclusions. The G8 + 5 group brings major developing emitters like China and India into the fold, and the Major Economies Meeting (MEM), George  W. Bush’s brainchild, adds three other big carbon emitters—Indonesia, Australia and South Korea—into the mix. Together, the groups account for 80 percent of greenhouse gas emissions. Washington would prefer to settle the major points at the MEM before tackling the unwieldy 200-country United Nations gatherings, which are coming up against their deadline for a post-Kyoto treaty to be approved in Copenhagen in December of 2009. Coming out of Hokkaido empty-handed will make pre-Copenhagen talks this fall just that much messier.

Still, while none of the three groupings at Hokkaido will likely produce a major consensus on emissions caps, they are producing a lively diplomatic chess match. E.U. members, who want the group to commit to steep cuts in carbon emissions by 2050, are butting heads with Bush over his unwillingness to commit to numerical targets. Meanwhile, Japanese Prime Minister Yasuo Fukuda is trying to broker a compromise. With a more green-friendly Obama or McCain administration only months away, Fukuda apparently believes that a tussle with Bush is counterproductive. Instead, he’s pushing for agreements on less-polarizing issues, such as encouraging carbon capture and storage technology for coal power plants, promoting nuclear energy and lowering tariffs on clean technology.

“There are some folks out there who think the rest of the world can settle on their own agreement and expect the United States to then come and join under a new administration,” said Council on Foreign Relations environmental expert Michael Levi on a recent press conference call. “But the Japanese understand that, regardless of substance, the United States is going to have to be part of creating whatever agreement happens if there’s any chance that the U.S. will end up being part of that agreement.”