CBSE Class 10 Answered

Global warming is caused by several factors. Emission of green house gases is one of the most important causes. Burning of fossil fuels, especially in automobiles and industries, burning of coal and natural gases releases large amounts of green house gases (like CO_2, methane, water vapour, sulphur dioxide, nitrous oxide , CFCs etc) into the atmosphere. These green house gases form a lid on the earth's atmosphere, which prevents some of the heat from escaping. Instead, it is reflected back to the earth's surface, where it raises the temperature of earth. That's called the greenhouse effect. In addition, pollution from factories, carbon dioxide from rotting trees all lead to global warming. Deforestation is another important cause.