Getting the measure of farming’s environmental impacts Andrew Balmford Conservation Science Group

1. Getting the measure of farming’s environmental impacts Andrew Balmford Conservation Science Group Department of Zoology University of Cambridge APPG Science & Technology in Agriculture Westminster, 19 March 2019

2. Agriculture is the biggest threat to biodiversity habitat clearance for new farmland intensification of existing farmland

3. Land sharing Green et al. 2005 Science 307: 550 • keeping hedgerows, copses, ponds, and patchwork landscapes • reducing chemical inputs • until recently, €5B/y agri-environment payments across EU • typically reduces yield (production/area)

4. Land sparing Green et al. 2005 Science 307: 550 • if sharing lowers yield, need more area under farming • alternative: high-yield farming on sufficient land to meet demand combined with retention or restoration of intact habitats elsewhere in region

5. Land sparing Land sharing   40 10 studies, 5 continents, over 2000 species 60 Ghanaian birds, trees Indian birds, trees, butterflies Ugandan birds Brazil/Uruguay pampas birds, dung grasses, beetles, daisies Kazakhstan birds Mexican birds, trees, dung beetles Polish birds, trees, sedges 0 20 Hodgson et al. 2010 Ecol. Lett. 13: 1358; Phalan et al. 2011 Science 333: 1289; Hulme et al. 2013 PLoS ONE 8: e54597; Gilroy et al. 2014 Glob. Ch. Biol. 20: 2162; Feniuk 2015 PhD thesis; Kamp et al. 2015 J appl. Ecol. 52: 1578; Dotta et al. 2016. Cons. Biol. 30: 618; Williams et al. 2017 Glob. Ch. Biol. 23: 5260; Finch et al. 2019 Cons. Biol. in press Colombian birds, dung beetles UK birds and butterflies

6. Other costs of high-yield farming Balmford et al. 2018 Nature Sust. 1: 477 Because yields vary across different systems, need to compare costs per unit of production

7. Cost-cost plots Balmford et al. 2018 Nature Sust. 1: 477

8. Cost-cost plots: Chinese paddy rice greenhouse gases water

9. Cost-cost plots: UK wheat greenhouse gases nitrogen

10. Cost-cost plots: Brazilian beef greenhouse gases

11. Cost-cost plots: UK dairy nitrogen greenhouse gases phosphorus soil

12. Recap • Land sparing - retaining/restoring large areas of habitat through high yield production elsewhere - much better for most species than sharing Phalan et al. 2016 Science 351: 450 • High-yield farming raises concerns about other costs • Costs should be compared per unit production, but data very limited • Initial cost-cost plots indicate some high-yield systems have relatively low environmental costs

14. High-yield farming for climate change mitigation? Rhys Green Conservation Science Group Department of Zoology University of Cambridge APPG Science & Technology in Agriculture Westminster, 19 March 2019

15. Farming and greenhouse gas emissions Lamb et al. 2016 Nature Clim. Change 6: 488 Agriculture 10% of UK greenhouse gas emissions Legally binding commitment to  by 80% (cf 1990) by 2050 Royal Society 2011: on-farm approaches “… not nearly sufficient to realise 80% cut…”

16. Farming and greenhouse gas emissions Lamb et al. 2016 Nature Clim. Change 6: 488 Agriculture 10% of UK greenhouse gas emissions Legally binding commitment to  by 80% (cf 1990) by 2050 Royal Society 2011: on-farm approaches “… not nearly sufficient to realise 80% cut…” What about scope for yield increases + restoring CO2-sequestering habitat on spared land? carbon sequestration greenhouse gas emissions

17. Farming and greenhouse gas emissions Lamb et al. 2016 Nature Clim. Change 6: 488 expect 38% ↑ in UK demand, 2010-50 2050 land conversion no yield growth  ↑ ↑ emissions 2050 on farm 1.3%/y yield growth  ~80% ↓ in emissions 2010 target 0 mean yield change 2010-50 1.3%/y

18. Past and future yield scenarios for some UK crops Lamb et al. 2016 Nature Clim. Change 6: 488

19. Balmford et al. 2018 Nature Sust. 1: 477

20. Balmford et al. 2018 Nature Sust. 1: 477

21. Conclusions • UK demand for agricultural products is likely to increase markedly by 2050, though reducing food waste and changing diets away from animal products may have effects High-yield farming could potentially meet increased demand and spare land to grow unharvested non-crop plants (such as trees) that would sequester carbon long-term • Modelling indicates that projected increases in yield of UK crops and livestock could allow net GHG emissions from agriculture to decline by 80% between 1990 and 2050, as required by the Climate Change Act 2008. This requires land sparing for non-crop vegetation and yield increases by 2050 near the top end of the plausible range.

22. Conclusions • Taking into account the potential for establishing or conserving carbon sequestering non-crop vegetation on land spared by high-yield farming has a marked effect on net GHG emissions per tonne of product in favour of high-yield (low land cost) farming methods. Even without this LUC effect, low land cost (high-yield) methods do not always have high environmental costs per tonne of product. • Linking the promotion of high-yield but low-externality cost farming to large-scale establishment of non-crop vegetation on other land could deliver the benefits of land sparing, but this would require policy mechanisms not yet in existence.

24. Farming and greenhouse gas emissions Lamb et al. 2016 Nature Clim. Change 6: 488 Modelled effects on UK GHG emissions, when combined with land sparing, of: Reduction in calories from animal products Reduction in food waste Zero net Zero net 80% reduction 80% reduction 2010 emissions 2010 emissions

25. Three-compartment land sparing

28. Conclusions so far… • On demand side: • scope for making better use of food waste • nudging has some potential to shift diet • … but agricultural demand will still grow markedly On supply side, for taxa/regions studied (only!): • most spp. will  as food production  • land sharing will support some spp. • high-yield farming is better for most – especially small-range and specialist spp. - provided policy and governance regimes encourage land sparing • in UK, high-yield farming + habitat restoration could greatly  agricultural emissions • data limited, but some high-yield techniques may have lower environmental costs in other ways

29. What the data say across all groups examined, most species are sparing-preferring losers: 859 bird spp 86 dung beetle spp 54 butterfly spp 77 daisy spp 420 tree spp 103 grass spp Phalan et al. 2011 Science 333: 1289; Hulme et al. 2013 PLoS ONE 8: e54597; Feniuk 2015 PhD thesis; Kamp et al. 2015 J appl. Ecol. 52: 1578; Dotta et al. 2016. Cons. Biol. 30: 618; Williams et al. 2017 Glob. Ch. Biol. 23: 5260

30. What the data say Hulme et al. 2013 PLOS ONE 8: e54597 Feniuk 2015 PhD thesis Kamp et al. 2015 J appl. Ecol. 52: 1578 Dotta et al. 2016. Cons. Biol. 30: 618 Williams et al. 2017 Glob. Ch. Biol. 23: 5260 Number of species similar results for: Ghanaian birds, trees Indian birds, trees, butterflies Ugandan birds Pampas birds, grasses, dung beetles, Asteraceae Kazakhstan birds Mexican birds, trees, dung beetles Polish birds, trees, sedges 0 20 40 Food production: GJ ha-1y-1 60 Food production: GJ ha-1y-1 Colombian birds, dung beetles UK birds and butterflies Gilroy et al. 2014 Hodgson et al. 2010

31. % threats to birds attributable to agriculture developed developing 225 1,039 95 687 Green et al. 2005 Science 307: 550 Environmental significance of farming • farming already: • covers > 50% of useable land • has ~ doubled N fixation rates • source of 19-35% of GHG emissions • has caused >40% of observed sea-level rise, 1961-2003 • is focused in high-biodiversity regions • is biggest source of threat to spp. global food demand may≥ double by 2050 Tilman et al. 2011 PNAS 108: 20260

32. Two demand-side projects • Cutting/better using waste currently ~1/3 of all food produced Erasmus zu Ermgassen EU adoption of E Asian practices for feeding food waste to pigs could: free up 1.8Mha of cropland  12/14 other env’tal impacts (cf anaerobic digesters)  production costs … and is supported by 75% of producers surveyed zuErmgassen et al. 2016 Food Policy 58: 35 Salemdeeb et al. 2017 J. Cleaner Prod. 140: 871 zuErmgassen et al. 2018 PLOS ONE 13: e019628

33. Two demand-side projects 2. Reducing demand for meat (esp. beef, lamb) GHG (land, water, N…) footprint of meat (esp. ruminant) >> alternatives Tilman & Clark 2014 Science 515: 518 Emma Garnett altering choice architecturein cafes to test scope for nudging people to eat less meat

34. Two contrasting approaches On-farm biodiversity is declining Trade-off between yield and on-farm biodiversity land sharing land sparing • keeping hedgerows, copses, ponds – and patchwork farms • reducing chemical inputs • until recently, €5B/y agri-environment payments in EU • typically reduces yield (production/area) • if sharing lowers yield, need more area under farming • high-yield farming on converted land combined with retention or restoration of intact habitats Green et al. 2005 Science 307: 550

35. Some model landscapes intermediate yield land sparing land sharing yield: zero low intermediate high land use: natural habitat farming The tradeoff: density-yield curves Loser Winner Land sparing best density density density Loser Loser Land sharing best Intermediate best yield yield yield

36. India study: • measured crop yields and population densities of all birds and trees • 20 1km2 study areas spread across yield gradient Malvika Onial 2010 PhD thesis What the data say • Ghana study: • measured crop yields and population densities of all birds and trees • 25 1km2 study areas spread across yield gradient but matched for soils, climate, etc. Ben Phalan 2009 PhD thesis oil palm plantation farm mosaic forest

37. Other externalities of high-yield farming Balmford et al. in press Nature Sust.

38. Caveats and next steps 1. Need to consider other consequences of high-yield farming other externalities, water flows, cultural values, recreation … food is not just calories and protein – other nutrients, accessibility rural livelihoods

39. Caveats and next steps integrated pest management e.g. push-pull vs maize stemborers • 2. Need to identify yield-enhancing systems with relatively low environmental costs silvopastoralism Broome et al. 2013 Proc. R. Soc. Lond. B. 280: 20132025 co-culture Khan et al. 2014 Phil. Trans. R. Soc. Lond. B. 369: 20120284 genetic modification Xie et al. 2011 PNAS 108: E1381 key metrics: yield, env’tal cost/kg

40. Caveats and next steps 3. Need to identify and implement explicit linkages between high-yield farming and land sparing • Phalan et al. 2016 Science 351: 450 price effects alone limited Ewers et al. 2009 Global Change Biol. 15:1716 Stevenson et al. 2013 PNAS 110: 8363 market-based incentives e.g. eco-certification, preferential access to credit Balmford et al. 2012 Proc R Soc Lond B 279: 2714 command-and-control measures e.g. land-use zoning, protected areas, legally-required offsets Nepstad et al. 2014 Science 344: 1118

41. Caveats and next steps publicly-funded financial incentives e.g. agricultural subsidies and taxes, PES strategic deployment of investments e.g. new/improved roads, extension officers, irrigation Laurance et al. 2014 Nature 513: 229 Sankaran & Madhusudan 2010 Hindu Surv. Env. 2010: 113 Nature Conservation Foundation e.g. micro-loans for anti-crop-raiding fences

44. Other externalities of high-yield farming