how can local environmental changes have global effects?; why are there different theories about the effects of global warming?; which of the following statements about current theories on global warming is true?; it is not possible for global warming to have any positive side effects.; some scientists believe that global warming will lead to an increase in disease and starvation.; how does an increase in the annual melt season in antarctica have a global effect?; some scientists believe that global warming will bring about extreme weather.; scientists disagree about the possible effects of global warming.