Modesto Bee: What if you needed a heart transplant, but you put off surgery until you became so weak an ambulance had to deliver you to the emergency room? By that time, you would be in immediate danger. That’s a lot like what’s happening with global warming. Unless you’re a scientist studying atmospheric chemistry, or you’re paying very close attention to the global warming debate, the earth doesn’t appear to be in immediate danger. But when scientists go looking for telltale warnings, they find …