People and Factories, Cellular respiration and burning fossil fuels
Plants take CO2 and sunlight to make sugar and oxygen. When Animals eat the plants it also eats the sugar because the plants created the sugar. When the Animals dies the body decomposes and the sugar go's with the deceased body to the ground.
fuels of the factory releases CO2 and pollutes the system which blocks the organisms to grow plants and when it blocks the organism it the fuel spreads all around which is not good because it has carbon dioxide in it and it could kill you instantly and when it releases it could have a chance to burn wood and could start a fire.
When the Plants receives CO2 from the sunlight it produces sugar, And when an animal eats the plant it eats the sugar from the plant too. When a huge animal eats the smaller animal it eats the sugar inside the small animals stomach. When the huge animal dies the remains are there and the sugar stay there.