1. Agriculture is directly responsible for about 7 per cent of total UK greenhouse gas emissions (CO2 = 1%, N2O = 3.5%, CH4 = 2.5%).
2. Around one per cent of this total (actually 0.7%) is carbon dioxide (CO2) from direct energy use in agriculture (just like energy-related carbon dioxide emissions in the rest of the economy, this may be reduced dramatically through energy efficiency and low-carbon renewable energy substituting for fossil fuels).
3. About half of the total is due to nitrous oxide (N2O) emissions from agricultural soils (an inevitable consequence of crop and grass production, whether using organic or mineral fertilisers - there are no easy ways to reduce this by more than a few per cent).
4. The remainder (roughly 2.5% of the UK total) comprises methane (CH4), mostly from ruminant livestock (also difficult to reduce, at least in the short term).
5. Indirect emissions attributed to agriculture (energy used and N2O emitted in mineral fertiliser manufacture, not normally counted as part of agricultural emissions) would add about another 0.5-0.7% to the agricultural contribution
6. The food chain as a whole is sometimes blamed for as much as 18-20% of UK greenhouse gas emissions, but much of this total arises 'beyond the farm gate' in food processing, consumption or waste disposal, or indirectly through changes in land use attributed to agriculture elsewhere in the world. Some sources of information confuse UK farms with the food chain as a whole, UK production with UK consumption, or UK figures with worldwide figures.
7. Since points 3. and 4. (above) involve biological processes with only limited opportunities for management, there is a danger that government measures to reduce UK agricultural greenhouse gases would simply 'export' these emissions by shifting agricultural production to other countries.
8. While UK agriculture gradually adapts to climate change, we can also improve the 'greenhouse gas efficiency' of resource use in agricultural production, store more carbon in vegetation and soils, and use bioenergy and other renewable energy technologies for self-supply and energy export, helping to reduce emissions elsewhere in the economy.
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