Associated Press: California is defined by its scenery, from the mountains that enchanted John Muir to the wine country and beaches that define its culture around the world. But as scientists try to forecast how global warming might affect the nation’s most geographically diverse state, they envision a landscape that could look quite different by the end of this century, if not sooner. Where celebrities, surfers and wannabes mingle on Malibu’s world-famous beaches, there may be only sea walls …