Short essay(800words) on global warming. Include 1) the data or records that support global warming is in fact ocurring; 2) the natural and human-generated causes for global warming; 3) negative and positive (if any) consequences of global warming ; 4) the predictions of General Climate Model simulation and IPCC report; and 5) the efforts to slow down the rate of global warming (i.e., the warming trend is natural fluctuation, etc.), please give your idea and supporting evidence.