Agriculture is only directly responsible for a small percentage of carbon emissions, but it is responsible for a higher percentage of total greenhouse gas emissions due to emissions of methane (particularly from cows) and nitrous oxide (from the use of manure and artificial fertilizers). For example, agriculture emits 1% of UK carbon, but 7% of total UK greenhouse emissions, because 36% of UK methane emissions and 67% of UK nitrous oxide emissions are from agriculture. (Emissions of non-carbon greenhouse gases from UK agriculture fell 18% from 1990 to 2006, but need to be reduced much further.)
Agriculture can also cause very significant emissions from the soil or can provide carbon sinks, to take or keep carbon out of the atmosphere. This is partly because plants take up carbon dioxide as they grow, which is then usually emitted when the plant is used (for fuel or food), and partly because carbon is stored in soil. It follows that pasture creates a significantly better sink than arable land. Over the last 150 years, the rapid conversion of forests, semi-natural vegetation and grassland to croplands means that, globally, much soil organic carbon has been lost.
However, despite the deforestation and changes in agricultural practice, forests and farmland remain major sinks for carbon emissions. Approximately 10% of current US greenhouse gas emissions are taken up by US forests or agriculture (see US EPA – Carbon Sequestration in Agriculture and Forestry).
Therefore, as well as being beautiful, vital for biodiversity and home to millions of people, forests are crucial carbon sinks. Reforestation is necessary, but will not provide significant new sinks soon enough to control climate change. More important is to prevent deforestation and this must be a priority in national and international discussions about the replacement for the Kyoto Protocol. Some forests should remain untouched (except by those who live in them), but others should be better managed. For example, more regular harvesting of wood waste (which does not mean felling trees) would increase the amount of wood available to generate renewable electricity and not damage the health of the forest. However, there will usually be some loss of biodiversity – half of natural forest is dead wood, so removing it will reduce wildlife habitats.
Reducing agriculture’s climate impact
How should the climate impact of agriculture be reduced? Ploughing releases carbon from the soil, but crops can be grown without ploughing. However, this increases the emissions of nitrous oxide, another greenhouse gas, so may damage the climate more than ploughing does. Using crop residues to make compost and turning manure into biogas are other routes.
An important study, Greenhouse Gas Mitigation through Agriculture by Uwe Schneider and Pushpam Kumar, points out that the full effects of different approaches must be taken into account, including the potential for ‘carbon leakage’ if an approach in one area requires more land globally to be used for farming, which often leads to deforestation. Some approaches are good, some neutral, and some bad. As they write:
Examples of relatively neutral strategies include carbon sequestration via reduced tillage, moderate crop residue use for bio-energy generation, livestock manure management, use of low-emission fertilizers, and crop-demand based fertilization. Land intensive mitigation strategies, on the other hand, have a high leakage potential because these strategies decrease traditional agricultural commodity supply and provide incentives to expand agriculture elsewhere. Thus, high leakage potentials exist for afforestation of agricultural land, dedicated energy crop plantations and wetland restoration.
None of these conclusions are uncontroversial, for example:
- Some recent science questions the climate advantages of reduced tillage.
- Crop residues may be more effectively incorporated into soil to increase soil carbon.
However, the key point is that the full direct and indirect effects of any change must be considered.
Nevertheless, there is great potential for reducing agriculture’s contribution to climate change, through transforming national and regional policies and changing behaviour. The urgent priority is to replace intensive agriculture with organic agriculture.
Organic agriculture has a much lower climate footprint than intensive agriculture, because of lower emissions and increased carbon sequestration. Organic systems do not use artificial fertilisers – nitrous oxides from such fertilisers are the second largest agricultural greenhouse emissions, after methane. Instead, organic farmers use natural fertilisers such as legumes.
Reduced emissions alone mean that organic agriculture has about an 18% lower climate footprint. A Food and Agriculture Organisations (FAO) report says that, with soil carbon sequestration, the climate impact is 60% lower (see Institute of Science in Society: FAO Promotes Organic). In addition, work on an experimental farm has indicated that the climate impact of organic farms could be 80% lower (see Organic Farming and Climate change).
Therefore, major policy changes are needed to promote organic agriculture. This will also be beneficial for human health, for biodiversity, create many more jobs, be much better for animal welfare, require less irrigation and lead to less rapid run-off from farmland, so reducing flooding. Another benefit will be the maintenance and building of soil fertility on land threatened by degradation and erosion.
Current organic levels
Certified organic agriculture worldwide tripled between 2000 and 2006. The countries with the greatest organic areas are Australia, China and Argentina. Latin America has the greatest total number of organic farms. In Europe, Italy has the largest organic area and the highest number of farms.
However, organic agriculture still represents only a tiny percentage of the total. Organic food accounts for less than 2% of food sales worldwide. The following are percentages of certified organic agriculture. Note that because certification excludes forests and harvesting of wild plants and not every organic farm will be certified, actual figures, particularly in the developing world, will be higher.
(Statistics from The World of Organic Agriculture.)
The low levels of organic agriculture are primarily due to the policies of major countries or regions, which promote intensive agriculture. The EU’s Common Agriculture Policy (CAP) is rightly infamous for its destruction of wildlife and landscapes. Its contribution to climate destruction must become better known and be halted. The Agenda 2000 paper A CAP for the future, agreed in 1999 and announced by the EU with great fanfare as a means of making the CAP sustainable, does not even mention climate change.
The CAP gives much more money to intensive agriculture than to organic, although the 1992, 2000 and 2003 reforms improved things slightly. The 2003 decoupling of payments from production does favour more extensive farming systems and thus benefits organic farming. However, less than 15% of CAP money goes to organic agriculture. The other 85% of taxpayers’ money is spent in ways that drive climate destruction.
EU member states have some powers to implement the CAP in ways which are better for organic farming. In all EU countries, organic farms receive fewer direct payments per hectare than conventional farms but, in Austria and Finland, it is only 6 to 8% lower, whereas in Spain, Denmark and Portugal it is 33%. The average for member states is 18%.
The highest reported domestic market growth for organic farming, estimated to be as much as 30%, is in China, and an organic boom is also taking place in Indonesia
An important factor in promoting organic agriculture in developing countries is the demand from industrialised countries. For example, in Africa, demand is low, with some exceptions (for example, Egypt and South Africa), but demand in Europe has led to more than one million hectares in Africa being certified as organic. (Additionally, 6.8 million hectares are certified as forest and ‘wild harvested’ areas.) Demand from North America and Europe is also a major factor in promoting organic agriculture in Latin America – Brazil, Argentina and Chile all have organic export agencies
The largest market for organic produce is the USA, which grew by 17% in 2008. The EU is second (due mainly to high demand in Germany, the UK, Italy and Austria).
Organic farming often means a lower yield than intensive agriculture. How much lower depends on the crop, the soil and so on. However, organic yields improve over time as the soil improves and builds up fertility. Such soils are also better suited to climate adaptation, for example, they retain more water and are therefore better in years of drought.
In 2002, the Research Institute of Organic Agriculture in Frick, Switzerland, published a report on the evidence from a 21-year comparative study. It found that organic crop yields on were, on average, 80% of intensive ones. Not all crops did equally well – organic potato yields were only 60%, but organic winter wheat achieved 90%, and grasses fed on manure did just as well as those fed on fertiliser (see New Scientist: 20-year study backs organic farming).
Most US farmers use less artificial fertiliser than European farmers, so the yield difference is less.
A recent UNCTAD report about organic farming in Africa
The yield of different forms of agriculture also depends on access to inputs. A 2007 study led by Ivette Perfecto of the University of Michigan found that, in developed countries, organic systems on average produce 92% of the yield produced by intensive agriculture. However, in developing countries, organic systems produce 80% more than intensive farms, because the materials needed for organic farming are more accessible than artificial pesticides and fertilisers. Although organic production tends to require more labour, this labour is spread out more evenly over the growing season, making it easier to manage (see New Scientist: Organic farming could feed the world). A recent report from the UN Conference on Trade and Development (UNCTAD) says that, in Africa, organic agriculture increases yield by 130% (see UNCTAD: Organic Farming could Feed Africa).
Farms and forests as a source of renewable energy
Farms should be used as a source of renewable energy, as well as food. Through Anaerobic Digestion (AD) – a process in which micro-organisms break down biodegradable material in the absence of oxygen – farm waste can be turned into renewable gas (that is, ‘biogas’), which can then be fed into the existing natural gas network. The remaining solid material can be used as a fertilizer. The UK Committee on Climate Change, in its December 2008 Report (see Chapter 9: Non-CO2 greenhouse gases), suggests that emissions from agriculture could be substantially reducing through AD, either centrally or on site at the farms, and that this would actually be cost beneficial to farmers.
‘Biomass’ is the name given to plants used to create energy. It can be burnt whenever needed, so is not intermittent, in the way wind or solar power is. Burning biomass also produces heat, so biomass should always be used in a Combined Heat and Power plant.
Since the plants absorb carbon while growing and then release it when burnt, getting energy from biomass is potentially carbon neutral. However, the actual climate impact depends on the source of the biomass. If it is from crops grown on fields converted from grassland or forest, or is grown with intensive of chemical fertilisers and pesticides, or transported a long distance, the climate impact may be damaging. The best source of biomass is waste wood, for example, from forests that have been managed properly. Short rotation coppice – fast growing trees which are cut down for biomass and replaced by new trees – is also good. Some energy crops, notably miscanthus, are potentially good in climate terms, but only if the land used to grow them is not converted from grassland. And the global food situation must always be considered in any approach to energy crops.
Plants can also be used to produce transport fuels, known as ‘biofuels’. This is strongly supported in the US, for energy security reasons. The Obama White House says that it is promoting biofuels “for increasing the national supply of home-grown American renewable fuels as an alternative to foreign sources of oil”.
The EU is also promoting biofuel – the Renewable Transport Fuel Obligation requires suppliers to include 5% renewable fuel in all transport fuel sold in the EU by 2010. Transport fuel is also part of the EU Renewable Directive target that 20% of all energy should be from renewables by 2020. It states that 10% of transport fuel should be renewable, but electric vehicles running on renewable power do not count towards this target. This is because the renewables have already been counted towards electricity targets, so this is effectively a 10% biofuel target.
However, the biofuel most commonly used today is ethanol, fermented from crops such as corn, rapeseed, sugar beet, soya oil or palm oil. Given how these crops are currently grown, this is likely to make climate change worse.
A detailed study of the impact of different biofuels was published in Finland in 2008 (see Greenhouse gas balances of transportation biofuels, electricity and heat generation in Finland). This concludes that current biofuels are three to five times worse for the climate than using oil. Finland has low carbon electricity generation – 57% of its domestic electricity generation is from renewables and 37% from nuclear. So, for countries with a high carbon electricity mix, such as the USA or Germany, the climate impact would be even worse.
4. Wind and hydro
Farms are also obvious locations for wind turbines. These take up very little of the land, are completely compatible with livestock or crops and provide the farmer with an additional source of income. Run-of-river hydro schemes are another option.
In the EU, food is responsible for about a third of individuals’ impact on the climate.
The FAO has calculated that the international meat industry, most of which is based on very intensive agricultural practices, generates roughly 18% of the world’s greenhouse-gas emissions. This is even more than transport. Meat production also uses much more water than any other food production – 2,400 litres of water to produce one hamburger.
However, different forms of meat have different climate effects, so this should not simply be a debate between vegetarians and omnivores. The UK Committee on Climate Change 2008 Report suggests that poultry meat is around a quarter as climate-heavy as beef or lamb. Pork is around a third as climate-heavy as beef. (However, these figures don’t include the loss of carbon from the soil used to grow protein crops such as soya needed to feed chickens and pigs. Cows and sheep can and should be fed on grass.)
Cows give off methane, which contributes to global warming. A cow produces around four tonnes of carbon-equivalent a year, more than the average car. Some recent research has suggested that this could be cut by a third by altering their feed, giving them different amounts of vegetable oil (see Agra Europe, 22 August 2008), but the current scientific consensus is that changing diet is unlikely to make much impact on methane emissions.
A 2009 Netherlands Environmental Assessment Agency report (see Climate benefits of changing diet), which analyses the costs of meat-based diets, estimates that a reduction in beef and pork consumption could cut $20 trillion off the cost of controlling climate change. It also states that reducing consumption of these meats would result in more land being available for vegetation to grow, which would result in a ‘carbon sink’.
However, because pasture produces a better carbon sink than arable land, an increase in free-range livestock may be a better climate option than an increase in cropland. Livestock can also graze on land, which is not available for arable. However, some land is not fertile enough for crops and, in some areas, arable is not allowed, for landscape, conservation or scientific reasons.
Fish is not covered in the Climate Change Committee’s report. It is potentially carbon-light – though usually bad for biodiversity reasons. However, the fact that shipping emissions are not yet regulated or much measured – for example, they are still outside the EU’s Emissions Trading Scheme – means that fisheries do have a significant climate impact due to the diesel used by ships.
Transporting food also has a significant carbon impact and food transport is a substantial part of total transport. For example, it is responsible for a quarter of UK lorry journeys. Supermarkets have national distribution systems, so even food labelled as locally grown may have travelled around the country to be prepared or packaged, before being transported back to be sold. Local farmers’ markets are an excellent way for consumers to ensure that what they buy is genuinely local.
However, food miles are not the most significant climate impact of food. A 2005 UK government report (see DEFRA: The Validity of Food Miles as an Indicator of Sustainable Development) suggests that it may be more energy-efficient to import tomatoes from Spain by lorry than to grow them in a heated greenhouse in the UK. (Obviously this depends how the greenhouse is heated. All organic greenhouses – which are not much heated – use combined heat and power.)
Food transported by air is obviously the most damaging, but is the fastest-growing way of moving food around.
Policy changes needed
Total policy transformation is urgently needed. All support and subsidy should go into organic agriculture. There is no other way to reduce agriculture’s emissions by the 80% required.
Obama’s manifesto promised to help organic farmers to get certification, to reform crop insurance so as to end the penalisation of organic farmers and to promote regional food systems. However, there has not yet been significant progress on policies to promote US organic agriculture.
There has been some progress in promoting farms as a source of renewable energy. The American Recovery and Reinvestment Act includes $6.9 billion for rural development activities, such as construction and renovation of rural water and wastewater systems, both of which could be used for renewable energy projects. (However, this programme also covers low income housing loans, broadband infrastructure in rural areas, rural business programs and construction of Forest Service facilities, so renewable energy will probably not get a very significant proportion.)
The Act also promises $800 million for biofuels research and development, loan guarantees for renewable power projects, including biomass facilities, and extends tax credits for biomass-based electricity. However, Obama’s promotion of current biofuels will add to climate change. There must be an immediate switch so that only biofuels, which have a lower climate impact than oil, receive any regulatory help or subsidy.