The use of fossil fuels is the main source of excess greenhouse gases. By driving cars, using electricity from coal-fired power plants, or heating our homes with oil or natural gase, we release carbon dioxide into the atmosphere. Deforestatione is another significant source of greenhouse gases, as exposed soils release carbon dioxide, and fewer trees mean less carbon dioxide conversion to oxygen. The production of cement c (for sidewalks, buildings, and other man made activities) involves a chemical reaction responsible for a surprisingly large amount of carbon dioxide in the atmosphere. Over the same period, the level of atmospheric methane, another important greenhouse gas, has risen by 151 percent, mostly from agricultural activities such as raising cattle and growing rice. Methane leaks at natural gas wells are another major contributor to climate change. A. The production of cement has caused climate change B. Methane and Deforestation are necessary and do not harm the environment. C. Many human activities on earth have caused damage to the earth and to the atmosphere and are causing climate change.