It's certain that you've heard of global warming. It's not certain that you worry about it. It's possible that you believe there is not much you can do. Like all national or international problems, efforts of one individual are like drop in a ocean in solving these problems. I am not sure whether I should worry about it. I do believe that prophesies of global warming and impending doom are real but I am pretty sure that this won't happen within my lifetime - and science backs me up here - and I am in general not much concerned about what happens after my death. Question is, should I be? It's my responsibility that not to exploit earth yet should I go out of my way to save it for future generations who have no real bearing on me? Of course, there is one school of thought which believes in self-extinction of human race. Argument is that humans have lived long and well on this planet and they should voluntarily extinct and give up world for other species. I actually find idea fascinating and am not averse to it. After all, why bother with what happens after me? Am I selfish for thinking so?
There was a time though, starting in 1950 or before and ending around 1990, when global warming was competing with global dimming. What happened was that some aerosols particulars were absorbing and reflecting sunlight back and hence there was decrease in energy on earth. Scientists now claim that that might have been factor in clouding effect of global warming for them to observe. More about this in this interesting piece on Guardian.