The G8 nations -- the United States, Britain, Japan, Germany, Italy, Canada, Russia and France -- are largely on board with a proposal to attempt to reduce emissions of carbon dioxide and other gases responsible for global warming by 50 percent by 2050.
But a major focus of the meeting in Kobe is midterm targets for 2020, which scientists say are needed to avoid a potentially disastrous rise in world temperatures of more than 3.6 degrees Fahrenheit over levels prior to the industrial age.
"A long-term goal is not a substitute for midterm, mandatory targets," said Matthias Machnig, Germany's environment minister.
The European Union has pledged a 20 percent emissions reduction by 2020, and has offered to raise it to 30 percent if other nations sign on. A U.N.-brokered agreement last December included a footnote referencing the need for cuts of between 25 percent and 40 percent.
The United States, however, has not committed to a midterm goal, demanding that top developing countries like China also commit to reductions. Japan has called for emissions by industrialized countries to begin to fall in the next one or two decades, but it too has stopped short of setting a 2020 target.
U.N.-led talks are racing to meet a 2009 deadline to strike an accord to take over from the Kyoto Protocol, whose first phase will expire in 2012. The head of those talks, U.N. climate chief Yvo de Boer, has said he fears enthusiasm for the effort was waning, and he called for G8 countries to send a stronger signal they were serious.
Japanese Environment Minister Ichiro Kamoshita, the host of the Kobe meeting, called for the world's richest countries Sunday to take the first steps in battling climate change, urging them to together reduce their emissions by more than 50 percent by mid-century.
"Developed countries should take the lead in emissions reductions and identify fair and equitable quantified national targets so that the global greenhouse gas emissions peak within the next 10-20 years," he said in an address, without specifying a reduction target.
Proponents say deep midterm cuts would force governments to take action quickly, spurring progress against warming. Goals for 2050 are important, they say, but give the world too much time to take steps that ought to be taken more urgently.
"Otherwise we are going to have a very nice long-term goal but no policy implication, (which is) what we really need, given the urgency of climate change," said Jos Delbeke, head delegate from European Commission.
Developing nations also have been pushing richer countries to make reduction commitments, arguing that global warming is a problem caused by industrialization that fueled the rise to affluence in North America, Europe and Japan.
Masnellyarti Hilman, Indonesia's head delegate, said her country aims to reduce emissions by 17 percent by 2020 and 22 percent by 2025. Indonesia is one of the leading carbon dioxide emitters in the world because of widespread deforestation.
But she said Indonesia and other developing countries were looking for strong signals from G8 countries that they are serious about reducing their own emissions quickly.
"For the long-term, I think the majority (have) already stated their target, but for the midterm target, they need to discuss," she said. "I think Japan (has) also not set a midterm target. We hope that they will take the lead."