as the main component of fossil fuels is carbon, that's why on burning fossil fuels,more and more carbon will be released in atmosphere in the form of carbon dioxide, carbon monoxide, methane etc and causing green house affect, global warming etc
b- cannot tell which change produced the results
Answer: ethics.
Ethics and moral are usually confused, but they are differente. You can think of ethic as the "science" whose object is to study (by the use of rigorous reflection) the human acts to distinguish right from wrong. While moral is related with costumes of a particular culture.