The rate of global warming and sea level rise may be slightly higher in the next century than previously predicted, particularly in the U.S., according to a peer-reviewed analysis released yesterday by the Pew Center on Global Climate Change. The U.S. and other nations have been working to cut sulfur-dioxide pollution in the air, which causes acid rain and health problems, but sulfur also reflects the sun’s heat and slows global warming, so removing sulfur from the air may have the side effect of raising temperatures and sea levels, according to the study, which is based on unpublished research gathered by the U.N. Intergovernmental Panel on Climate Change.