Climate change is a complex issue. One of the main causes is the emission of greenhouse gases into the atmosphere at a faster rate than their natural elimination, and agriculture is one of its chief contributors.
Carbon dioxide is the main greenhouse gas, and is produced by burning fossil fuels. In general, organic agriculture uses less fossil fuel per hectare and per kg of product than conventional agriculture. This is because the fertilisers and pesticides used in conventional farming need an extremely high energy input to make and transport, but organic farming relies on natural nitrogen fixation as its source of nitrogenous fertility and minimises the use of pesticides.
Moreover, organic farming leads to the uptake of more carbon dioxide from the atmosphere, ensuring that it is fixed into the soil, and the reduced soil erosion on organic farms also means less carbon is lost.
In fact, organic farming returns up to 15% more carbon to the soil than conventional fertiliser-based systems due to the increased soil fertility and humus content, greater microbial activity and soil depth. Nevertheless, because organic farms tend to be smaller than conventional farms, some of these savings may be offset by the increased use of fossil fuels in comparison with the savings on larger farms.
Nitrogen oxides and methane are two other gases that contribute on a per kg basis to global warming. Nitrous oxide, for example, is approximately 300 times more potent as a greenhouse gas than carbon dioxide. However, nitrous oxide emissions from organically managed soil are lower than emissions from non-organically managed soil simply because nitrogen oxides are produced in response to nitrogenous fertiliser, therefore much less is made on organic farms than on conventional farms.