Nature: Threatened with encroaching seas, dwindling water supplies and fiercer storms, Bangladesh is already suffering the ill effects of rising global greenhouse gas emissions. Mason Inman reports on how the region is coping with climate change. Ali Akbar Adi takes a break from steering his ox-driven plow across his small plot of land, digging furrows for a crop of lentils and beans. “When salt water comes in, the yields are very low,” he says. Storm surges push this salty water up …