Reuters: France and Brazil joined forces on Saturday to press the United States and China to make significant concessions at next month’s climate change summit in Copenhagen. In a joint document, French President Nicolas Sarkozy and President Luiz Inacio Lula da Silva of Brazil urged rich industrialized countries to cut emissions of greenhouse gases by at least 80 percent from their 1990 levels by 2050. They called on emerging countries to seek low carbon growth and to take steps to …