Add beer to chocolate, coffee, and wine as some of life’s little pleasures that global warming will make more scarce and costlier, scientists say. Increasing episodes of of extreme weather events are expected to reduce global barley production, a key ingredient in beer.  Losses of barley yield can be as much as 17 percent, an international group of researchers estimated. That means beer prices on average would double, even adjusting for inflation, according to a study in the journal Nature Plants.