Climate Change | Low Carbon Network

The greenhouse effect is a natural phenomenon and not a bad thing as many non-scientists assume. Without it the planet would be permanently ice-locked with an average global temperature of around -15 degrees Celsius.
Although there is much less methane in the atmosphere than carbon dioxide, it is a much more powerful greenhouse gas. According to the Intergovernmental Panel on Climate Change (IPCC) report Climate Change 2001: The Scientific Basis, published by Cambridge University Press in 2002, the Global Warming Potential (GWP) of a greenhouse gas is measured against that of carbon dioxide which is given a GWP of 1. Methane has a GWP of 62 over a 20-year period. The “Technical Summary” of the report states that the radiative forcing (heat retaining properties) of methane contribute 20% of the total forcing of all greenhouse gases.

What concerns scientists is not the naturally occurring greenhouse effect which is essential for life on the planet but the additional greenhouse effect caused by people. Scientifically this is referred to as the anthropogenic greenhouse effect. According to the Inter Government Panel on Climate Change (IPCC 2007) CO2 currently contributes about 55% to this anthropogenic greenhouse effect.
Biogeochemistry of Carbon
Carbon exists in many forms on the planet and the number of carbon atoms has not changed since the Earth’s formation – this is known as the carbon pool.
The study of the transformation of carbon from one form to another is known as biogeochemistry because it typically involves biological, geological and chemical processes. Carbon is said to cycle between forms and is stored for varying lengths of time within different reservoirs.
The carbon pool (49 x 1012 Gt C) exists in three principal reservoirs on the earth, specifically the atmosphere, the lithosphere (the earth’s crust e.g. coal) and the biosphere. The biosphere is the living part of the planet and even human beings are a Carbon-based life form. CO2 constitutes by far the largest proportion of carbon in the atmospheric reservoir (99%).
Burning fossil fuels transforms fixed carbon, which exerts no influence on climate, into CO2 which increases the anthropogenic greenhouse effect. However the reverse of this process is also occurring on a daily basis. The biosphere and specifically plant life such as trees remove atmospheric CO2 and transform it into fixed carbon via a process known as photosynthesis, which uses energy obtained from sunlight.
The Role of the Oceans
Many people assume that plants are restricted to land masses however the oceans contain billions of microscopic algae (very small plants) known as phytoplankton which also use CO2. Because of this the surface of the oceans are undersaturated with CO2 and therefore absorb more CO2 from the atmosphere via physical diffusion. In biogeochemical terms the oceans are said to act as a sink for atmospheric CO2. When these small plants die many sink to the bottom of the ocean and effectively remove carbon from the atmospheric reservoir for long geological time periods. In fact the oceans remove about one-half of the ~ 4.4 Gt anthropogenic CO2 from the atmosphere per annum.