Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2019 Oct 22;10(1):4641.
doi: 10.1038/s41467-019-12622-7.

The greenhouse gas impacts of converting food production in England and Wales to organic methods

Laurence G Smith  1   2 , Guy J D Kirk  3 , Philip J Jones  4 , Adrian G Williams  1
Affiliations

The greenhouse gas impacts of converting food production in England and Wales to organic methods

Laurence G Smith et al. Nat Commun. .

Abstract

Agriculture is a major contributor to global greenhouse gas (GHG) emissions and must feature in efforts to reduce emissions. Organic farming might contribute to this through decreased use of farm inputs and increased soil carbon sequestration, but it might also exacerbate emissions through greater food production elsewhere to make up for lower organic yields. To date there has been no rigorous assessment of this potential at national scales. Here we assess the consequences for net GHG emissions of a 100% shift to organic food production in England and Wales using life-cycle assessment. We predict major shortfalls in production of most agricultural products against a conventional baseline. Direct GHG emissions are reduced with organic farming, but when increased overseas land use to compensate for shortfalls in domestic supply are factored in, net emissions are greater. Enhanced soil carbon sequestration could offset only a small part of the higher overseas emissions.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Projected food production under conventional and organic farming methods. a Crop production and areas. *oilseed rape. b Livestock production and numbers. **sheep numbers × 10, ***poultry numbers × 100, ****milk production in Mt × 105. Conversion to 100% organic methods caused decreases in wheat, barley, oilseed rape, pigs, eggs, poultry meat and milk, and an overall decrease to 64% of the conventional baseline. Data of Smith et al.. Source Data are provided as a Source Data file
Fig. 2
Fig. 2
GHG emissions per unit production under conventional and organic farming methods. a Crops. b Livestock, including emissions in feed production. N2O = nitrous oxide, CH4 = methane, CO2 = carbon dioxide. Production is expressed in tonnes (t) of total metabolised energy. Data are means ±1 standard deviations from the uncertainty analysis (Methods). Emissions due to land use change overseas to compensate for shortfalls in home production, and enhanced soil carbon sequestration under organic methods, are not allowed for. Organic dairy, beef and sheep production have lower total GHG emissions per tonne of product, although greater forage intake increases CH4 emission. Less N fertiliser use in organic farming gives N2O and fossil energy use savings per tonne of product. Exceptions are crops receiving less N fertiliser in conventional farming (beans, oats), organic crops requiring flame weeding (carrots) and organic vegetable crops with lower marketable yields (potatoes, onions). Source Data are provided as a Source Data file
Fig. 3
Fig. 3
Total GHG emissions from food production for England and Wales (E & W) under conventional and organic farming methods. a For food crops for human consumption both from home and overseas production. b Additional net emissions due to soil C sequestration (CS) and overseas land use changes (LUC) to compensate for shortfalls in home production: High = all LUC by conversion from grassland, no CS; Medium = 50% of LUC by conversion from grassland, moderate CS; Low = 25% of LUC by conversion from grassland, high CS; COC= carbon opportunity cost of Searchinger et al. (Methods). c For livestock both from home and overseas production, including emissions during production of crops fed to livestock. d Additional net emissions due to CS and overseas LUC to compensate for shortfalls in livestock production: High, Medium, Low as for Crops. Note LUC losses and CS gains both only apply over the first few decades following conversion, however a flat rate is applied here. Data are means ±1 standard deviation from the uncertainty analysis (Methods). Source Data are provided as a Source Data file
Fig. 4
Fig. 4
Overseas land area needed for imported food. The area required to offset shortfalls in domestic production under organic methods is over five times that under conventional methods, largely due to imports of oilseeds, pork, poultry meat, eggs and milk. Note only the products listed in Fig. 1 are included; products that are not produced in the UK on a large scale (such as maize, rice, tea, coffee and sugar cane) are excluded (Methods). Source Data are provided as a Source Data file
See this image and copyright information in PMC

References

    1. Helm, D. Green and Prosperous Land: A Blueprint for Rescuing the British Countryside (William Collins, London, 2019).
    1. Meier MS, et al. Environmental impacts of organic and conventional agricultural products–Are the differences captured by life cycle assessment? J. Environ. Manag. 2015;149:193–208. - PubMed
    1. Williams, A. G., Audsley, E. & Sandars, D. L. Determining the Environmental Burdens and Resource Use in the Production of Agricultural and Horticultural Commodities (Defra, London, 2006).
    1. Nemecek T, Dubois D, Huguenin-Elie O, Gaillard G. Life cycle assessment of Swiss farming systems: I. Integrated and organic farming. Agric. Syst. 2011;104:217–232.
    1. Haas G, Wetterich F, Köpke U. Comparing intensive, extensified and organic grassland farming in southern Germany by process life cycle assessment. Agric. Ecosyst. Environ. 2001;83:43–53.

Publication types