Miami Herald: Few foods are more associated with home and hearth than bread. For centuries farmers have labored to master the elements and produce the crops that literally would put bread – whether in the form of corn tortillas, wheat chapattis or a loaf of rye – on the table for their families. The struggle against nature’s extremes has never been easy, but global warming seems poised to make things even harder for many farmers. Indeed, according to a new study, global warming-induced changes in …