Reuters: Delegates at U.N. climate talks resisted U.S. pressure to delete tough 2020 guidelines for cutting greenhouse gases with the European Commission saying they were a "crucial" element in a draft text. The U.N.-led talks have become dominated by disputes over whether a text should keep a mention of a need for rich nations to axe greenhouse gas emissions by 25 to 40 percent below 1990 levels by 2020 to avoid the worst impacts. Any watering down or removal of the …