Agence France-Presse: US President George W. Bush pledged Sunday to play a “constructive” role on climate change at a summit of rich nations, but hopes for a breakthrough were dim as he pressed developing countries. Japan, the host of the three-day Group of Eight summit, pushed for progress in the fight against global warming but environmentalists said that any agreement was unlikely to be far-reaching. “Yeah, I’ll be constructive,” Bush told a joint news conference after meeting …