Improved water, food, sanitation = improved nutrition, cleaner fuels. We have many global problems: global warming, population growth, habitat destruction, resource depletion. Today"s environmental degradation is rapidly an unprecedented global crisis: caused by population growth and industrialization. In the past 100 years: manufacturing increased, use of fossil fuels increased, number of automobiles, production of synthetic chemicals. In 150 years: we have 30% concentration of carbon dioxide, ozone destroying chlorofluorocarbons. Human made emissions have led us to acid rain. Biologists and ecologists have an idea where the human health reflects the health of a complex ecosystem. Some believe that the harmful things humans do to the environment can undo itself with the help of technology. We avoid talking about the global change we are experiencing because it may be too frightening or overwhelming. Some believe we are experiencing global warming"s effects as we speak. Science has proven that the earth is warming, and ghg are part of the cause.