Climate forcings is a general term that encompasses all the man made and naturally occurring influences of climate change. Climate forcing include positive forcings, which contribute to the increase in the earth's temperature, and negative forcings, which contribute to the decrease in the earth temperature. An example of a negative forcing is cloud cover that reflects light from the sun back into space. A positive forcing would included black soot particulate released during the burning of diesel fuel. The combination of the two types of forcings will determine if the net change in the earth's temperature will be positive or negative. The variation and uncertainty related to each type of forcing makes it nearly impossible to accurately analyze the cumulative effect. (13)
Each forcing can be attributed to either natural occurring events or man made influences. Anthropogenic forcings are those created by man made technologies or processes. The anthropogenic forcings have lead to the belief that as a planet, we are experiencing AGW (anthropogenic global warming). The scientific basis for this belief lies in data that has been collected and analyzed reaching back as far as previous ice ages. An examination of the changes in composition of the atmosphere in the last 400,000 years through four cycles of ice ages reveals that the current concentration of CO2 in the atmosphere is the highest it has been and is continually on the rise. (13)
This information, along with recent data showing the rapid increase in atmospheric CO2 since the industrial revolution initiated in 1850, lead scientists to believe there is not just correlation of the data but also causation that relates the burning of fossil fuels to the increase in CO2 concentration to the increase in global temperature. (14)
Albedo of the earth
The albedo of the earth, also known as it's diffuse reflectivity, refers to the earth's cumulative ability to reflect radiation that impinges upon it from the sun. Snow, trees, water, clouds, aerosols, and black carbon are the largest contributors to the earth's albedo. Snow, clouds, and white aerosols all have a high albedo meaning they reflect most of the light. Vegetation, soil, and black carbon all have a low albedo meaning they absorb most of the radiation that strikes them. The average albedo of the earth is constantly changing but usually varies between 30% to 35%.
There is a direct influence of the albedo on global warming. If there are large areas of vegetation, they are sequestering large amounts of CO2 while at the same time absorbing alot of the energy that strikes them from the sun. If the vegetation is removed there would be localized increases in CO2 concentrations while at the same time decreases in the amount of energy being absorbed from the sun.