Description:
There are three main factors that directly influence the energy balance of the earth: the total energy influx, which depends on the earth's distance from the sun and on solar activity; the chemical composition of the atmosphere, and albedo, the ability of the earth's surface to reflect light. The only factor that has changed significantly in the last 100 years is the chemical composition of the atmosphere. This resource also includes a graphic that shows how the amounts of carbon dioxide (in parts per million), methane (in parts per billion) and nitrous oxide (in parts per billion) in the earth's atmosphere have increased from the year 1000 to the year 2000. The graphic also shows how the amount of radiative forcing, in watts per square metre, has increased for each chemical.