AFP: China will on Monday host its first UN climate conference as it seeks to showcase its green credentials, but hopes are dim that the event will yield major breakthroughs that environmentalists crave. Three thousand delegates will converge on the northern port city of Tianjin for the latest round of tortured United Nations negotiations aimed at securing a post-2012 treaty on tackling global warming. But even the most optimistic forecasts for the six days of talks foresee only …