redOrbit: U.S. scientists say they’ve determined soybean leaves grown at the high carbon dioxide levels predicted for 2050 respire more than under current CO2 levels. Researchers at the University of Illinois and the U.S. Department of Agriculture said their finding will help fine-tune climate models and could point to increased crop yields as CO2 levels rise. The scientists said plants draw CO2 from the atmosphere and make sugars through the process of photosynthesis. But they also …