I totally agree with your opinion. Carbon-dioxide are causing the Earth to warm up. Coal burning devices are one of the main causes of Global Warming because they can release carbon-dioxide and methane. Scientists are arguing about if coal-burning devices are the main cause of Global Warming or not. Research done by experts say that when you burn coal, it releases a chemical compound called sulfur-monoxide which is unstable. Thanks for your info...it'll really help me with my project about Global Warming.