One of the reports I have to review today summarises how much greenhouse gas emissions are caused by activities related to agriculture. The original academic paper was published in Nature ten years ago. It is important to note that, as you can see from the WRI report that I mentioned earlier, agriculture has made tremendous progress so that the situation may have changed.
Nature: Non-CO2 greenhouse gases and climate change
About 10.3% of the greenhouse gases from the European Union come from food-related schemes. If you take the emissions from households, that is about 17%.
If we frame it in terms of agriculture, 25% of carbon dioxide, 50% of methane and 70% of nitrogen oxides are emitted from this sector. Carbon dioxide persists in the atmosphere for more than 1000 years, methane gas and nitrogen oxides persist in the atmosphere for 10 to 100 years, and the greenhouse effect varies from gas to gas. So, it is impossible to make a general comparison, but greenhouse gases that are not carbon dioxide can be 100 times more effective than carbon dioxide. Food-related systems, including agriculture, mainly emit these non-CO2 gases.
On a global scale, the share of greenhouse gas emissions from agriculture is 70% carbon dioxide, 15% methane and 15% nitrogen oxides.
The reason carbon dioxide emissions are so high at 70% is that the agricultural industry includes fossil fuels used in processing crops, land-use emissions, and transport. Methane gas comes from livestock manure, and nitrogen oxides are associated with so-called chemical fertilisers.
We can see here that by reducing methane emissions by using it as biogas energy, we can reduce fossil fuels and carbon dioxide. Using the residues from biogas digester, as organic fertiliser, we can reduce the nitrogen oxides associated with chemical fertilisers. So you can see that biogas technology is a solution that kills three birds with one stone.