Slide 10: Biosphere
The biosphere is the sum total of all life on the planet. Whilst it clearly is a component of terrestrial processes, it is useful to consider it as a separate system.
The biosphere affects the albedo of the planet's surface considerably. Bare ground (desert) has an albedo of 0.3, whilst coniferous forests are generally between 0.09 to 0.15, absorbing far more solar radiation.
The biosphere also affects the fluxes of certain greenhouse gases. Whilst terrestrial vegetation can fix a certain amount of carbon in it's structure, many species of plankton utilise CO2 in the formation of their carbonate shells. When these plankton die, their shells sink to the ocean bottom, effectively removing it from the system, reducing the atmospheric concentration of gases by at least fourfold.
The biosphere also generates large amounts of aerosols such as spores, viruses, dust, bacteria and pollen that scatter and reflect incoming radiation.
Primary productivity in the oceans also generates dimethyl sulphides, which oxidise in the air to form small salt nuclei around which droplets form. These are responsible to a large extent for cloud formation over the ocean.