Why is the global climate warming?

Global warming is a "natural phenomenon". Because people burn fossil minerals to generate energy or cut down forests to burn, many greenhouse gases, such as carbon dioxide, are produced. This gas has high permeability to visible light from the sun and high absorption to long-wave radiation reflected from the earth, which is commonly called "greenhouse effect" and leads to global warming. In recent 100 years, the global average temperature has experienced two fluctuations: cold-warm-cold-warm, with an overall upward trend. Since 1980s, the global temperature has obviously increased. The consequences of global warming will redistribute global precipitation, melt glaciers and frozen soil and raise sea level, which will not only endanger the balance of natural ecosystems, but also threaten human food supply and living environment.