The agreement "is an important and significant step forward" in the efforts to fight global warming, said Koji Tsuruoka, director-general for global issues with the Japanese Foreign Ministry.

However, the Japanese official stopped short of describing the agreement as a breakthrough, noting: "It is naive to think a breakthrough can be made."

Considering the fact some of the G8 members, notably the U.S., have long refused to set numerical targets for its carbon emissions, some may argue that the G8 statement at least represents a step forward on the issue of climate change, analysts note.

However, many analysts quickly pointed out that a deal that falls short of mid-term targets is unlikely to make people take these long-term commitments seriously.

"Unless the G8 leaders agree on immediate action and medium-term targets for reducing their greenhouse gas emissions by 2020, any long-term promises will be unattainable," said Oxfam, an international aid agency.

Even on the long-term goal, the G8 nations' commitment looked shaky as they wanted to bring major developing countries on board.

In their process of industrialization, developed countries emitted huge amounts of greenhouse gas without binding limits, and their current per capita emissions are much higher than those in developing countries.

Economic interests was the key reason behind the G8 nations' failure to take a decisive move on climate change, reflecting the dilemma they are facing in solving global issues while carefully taking care of their own interests, according to the analysts.