The potential for land sparing to offset greenhouse gas emissions from agriculture

Abstract

Greenhouse gas emissions from global agriculture are increasing at around 1% perannum, yet substantial cuts in emissions are needed across all sectors 1 . The challenge of reducing agricultural emissions is particularly acute, because the reductions achievable by changing farming practices are limited 2,3 and are hampered by rapidly rising food demand 4,5 . Here we assess the technical mitigation potential offered by land sparingincreasing agricultural yields, reducing farmland area and actively restoring natural habitats on the land spared 6 . Restored habitats can sequester carbon and can offset emissions from agriculture. Using the United Kingdom as an example, we estimate net emissions in 2050 under a range of future agricultural scenarios. We find that a landsparing strategy has the technical potential to achieve significant reductions in net emissions from agriculture and land-use change. Coupling land sparing with demandside strategies to reduce meat consumption and food waste can further increase the technical mitigation potential, however economic and implementation considerations might limit the degree to which this technical potential could be realised in practice.We projected the mitigation potential of land sparing in the United Kingdom with reference to its binding commitment to reduce emissions by 80% by 2050 (relative to 1990 levels) 7 . We began by identifying a technically plausible range in the future yields of all major crop and livestock commodities produced in the UK, based on historic trends and future potential. We define yields as the annual tonnage of production per hectare for crops and the feed conversion ratio (feed consumed per kilogram of production) for livestock. Future yields could vary across a wide range, driven by a number of biophysical, technical and socioeconomic factors [8][9][10][11] . We assessed the likely bounds of this range based on an assessment of technical potential and reflect this in our projections, which span yield declines through to sustained long-term growth averaging 1.3% per annum across all commodities 3 (Table 1; Supplementary Fig. 1; Supplementary Discussion). For the avoidance of doubt, we do not equate our lower yielding scenarios with 'land sharing'.We next projected emissions attributable to UK agricultural production out to 2050, quantifying all sources of emissions that would be affected by a land-sparing strategy. We therefore quantified not only emissions reported under 'Agriculture' in the UK's greenhouse gas inventory 12 , but also emissions related to agriculture but reported in other sectors (e.g. farm energy use, agro-chemical production and land-use change), and emissions arising overseas due to imported feed for livestock (see Supplementary Table 2 for all emissions sources quantified). Our projections assumed that agricultural production increases from present levels in proportion to projected demand growth (Supplementary Table 1). In certain scenarios, projected UK farming capacity does not keep pace with demand growth. In such cases ...

The environmental sustainability of insects as food and feed. A review

“…The first point about reducing the demand for livestock products is, at least in theory, a powerful mitigation option (Schösler et al 2012;Hedenus et al 2014;Davis et al 2016;Herrero et al 2016;Lamb et al 2016). This is particularly true for ruminant meat.…”

“…This can be achieved by substituting animal protein with vegetable protein and making a transition from ruminants (e.g., cattle and sheep) (McAlpine et al 2009;Tilman and Clark 2014;Bryngelsson et al 2016) to lower impact species (e.g., pigs and poultry) (Steinfeld and Gerber 2010). Reducing meat consumption and combining this with land sparing have the potential to reduce greenhouse gas emissions (Lamb et al 2016) and increase biodiversity (Phalan et al 2011). Another mitigation measure is using feed with a low environmental impact for the production of fish, pigs or poultry.…”

A glimpse of the future in animal nutrition science. 1. Past and future challenges

“…In ruminant production, for instance, the maximum mitigation potential ranges from 4 to 7% depending on the level of adoption rate (historical adoption rates to full adoption rates) of technologies such as cultivated pastures, better nutrition, changes in land-use practices, and changing breeding (Thornton and Herrero, 2010). Lamb et al (2016), however, acknowledged that their technological advancements might be untenable in practice, leading us back to the starting point. These authors also alluded the fact that reducing meat consumption would alleviate the growth of GHG emissions and perhaps a legislative incentive would be needed in the form of taxation on meat.…”

“…In the livestock arena, the upper-bound livestock productivity gains of Lamb et al (2016) assumed that technological advancements would lead to continued genetic gains through breeding and improved animal health and nutrition. The authors did not provide exact ways in which these improvements could offset livestock GHG emissions.…”

“…Sustainability does not necessarily imply organic agriculture, though some organic components might be needed to establish sustainable farming systems (Reganold and Wachter, 2016). Lamb et al (2016) laid out the "land sparing" concept for parts of Europe. It essentially seeks to increase yields, leading to a reduction on farmland area to produce the same amount of food/feed, allowing farmland to be spared and used to offset GHG emissions.…”