Scientists and meteorologists are arguing about whether it is possible that the levels of carbon dioxide will increase to values double and even quadruple present values. This could happen over a peroid of decades. Evidence gathered from ice cores and after 1958 from direct atmospheric sampling shows that the amount of carbon dioxide in the air has been increasing for over 200 years. Before 1800 the density was about 275 parts per million by volume. It is about 355 parts per million by volume. This increase is believed to be due to the combination of increased burning of fossil fuels and before 1905 to deforestation. The total source is estimated to have been increasing at a high rate at least until 1973. From 1973 until 1990 the rate of increase has been much less. Growing trees can help cut down on green gases. This is where we enter the equation.