The world’s carbon dioxide emissions in 2007 exceeded even some of the direst predictions of climate scientists, growing 3 percent from 2006 according to an annual report from the Global Carbon Project. The climb in overall emissions last year was especially surprising given the economic downturn that was expected to help curb emissions. For the first time, developing nations took the lead in overall CO2 emissions, accounting for some 53 percent of the total, according to the report. China was also officially reconfirmed as the world’s largest CO2 polluter; it alone accounted for some 60 percent of the rise in worldwide emissions in 2007. The report also found that the world’s natural carbon sinks, such as oceans and forests that lock away carbon and keep it out of the atmosphere, have been absorbing some 3 percent less CO2 pollution since 2000 than they did in the first half of the 20th century. “We should be worried, really worried. This is happening in the context of trying to reduce emissions,” said Richard Moss of the World Wildlife Fund. “We’re already locked into more warming than we thought.”