It may seem difficult to believe that people's can actually change the Earth's climate. When people started using machines to make their easier, they also begin the climate and environment. Population , fossil fuel and deforestation continue to affect the mixture of gases in the atmosphere. Energy to run machines , light or heat our homes comes mainly from fossil fuels like coal and petroleum. Burning these fossil fuels releases greenhouses gases. Deforestation also plays a major part in the greenhouse as trees that help to carbon dioxide from the air are being cut down too quickly.