WRAPUP 5-Bush promises to be constructive on climate at G8

(For more G8 summit stories, click on [G7/G8]) (Recasts after Bush/Fukuda news conference)

*Chances poor of substantive deal on climate change

*Bush vows to be constructive, wants China and India on board

*Africa, rising oil and food prices also on busy agenda

By Tabassum Zakaria and Chisa Fujioka

TOYAKO, Japan, July 6 (Reuters) - U.S. President George W. Bush promised on Sunday to be constructive in talks on global warming but said a deal was impossible unless fast-growing China and India agreed to limit their greenhouse gas emissions.

Climate change is high on the agenda of the annual summit of the Group of Eight rich nations that starts on Monday at a luxury hotel on the lush northern Japanese island of Hokkaido.

"I'll be constructive. I've always advocated that there needs to be a common understanding and that starts with a goal," Bush told a news conference after meeting Japanese Prime Minister Yasuo Fukuda, the host of the three-day summit.

"And I also am realistic enough to tell you that if China and India don't share that same aspiration, then we're not going to solve the problem," said Bush, who turned 62 on Sunday.