Associated Press: The top U.N. climate official says negotiators are likely to hold at least four conferences this year, but without much expectation of concluding a binding agreement on global warming. Yvo de Boer says the main elements of a deal should be in place by the yearend conference in Mexico, but technical issues may wait until 2011. The goal is an agreement to control greenhouse gases and protect poor countries from the impacts of climate change. De Boer said two previously …