Editing IPCC:AR6/SRCCL/Chapter-5 (section)

==== 5.5.1.6 Cellular agriculture ====

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The technology for growing muscle tissue in culture from animal stem cells to produce meat, for example, ‘cultured’, ‘synthetic’, ‘in vitro’ or ‘hydroponic’ meat could, in theory, be constructed with different characteristics and be produced faster and more efficiently than traditional meat (Kadim et al. 2015 <sup>[[#fn:r858|858]]</sup> ). Cultured meat (CM) is part of so-called cellular agriculture, which includes production of milk, egg white and leather from industrial cell cultivation (Stephens et al. 2018 <sup>[[#fn:r859|859]]</sup> ). CM is produced from muscle cells extracted from living animals, isolation of adult skeletal muscle stem cells (myosatellite cells), placement in a culture medium which allow their differentiation into myoblasts and then, through another medium, generation of myocytes which coalesce into myotubes and grow into strands in a stirred-tank bioreactor (Mattick et al. 2015 <sup>[[#fn:r860|860]]</sup> ).

Current technology enables the creation of beef hamburgers, nuggets, steak chips or similar products from meat of other animals, including wild species, although production currently is far from being economically feasible. Nonetheless, by allowing bioengineering from the manipulation of the stem cells and nutritive culture, CM allows for reduction of harmful fatty acids, with advantages such as reduced GHG emissions, mostly indirectly through reduced land use (Bhat et al. 2015 <sup>[[#fn:r861|861]]</sup> ; Kumar et al. 2017b <sup>[[#fn:r862|862]]</sup> ).

Tuomisto and de Mattos (2011) <sup>[[#fn:r863|863]]</sup> made optimistic technological assumptions, relying on cyanobacteria hydrolysate nutrient source, and produced the lowest estimates on energy and land use. Tuomisto and de Mattos (2011) <sup>[[#fn:r864|864]]</sup> conducted a lifecycle assessment that indicates that cultured meat could have less than 60% of energy use and 1% of land use of beef production and it would have lower GHG emissions than pork and poultry as well. Newer estimates (Alexander et al. 2017 <sup>[[#fn:r865|865]]</sup> ; Mattick et al. 2015 <sup>[[#fn:r866|866]]</sup> ) indicate a trade-off between industrial energy consumption and agricultural land requirements of conventional and cultured meat and possibly higher GWP than pork or poultry due to higher energy use. The change in proportion of CO <sub>2</sub> versus CH <sub>4</sub> could have important implications in climate change projections and, depending on decarbonisation of the energy sources and climate change targets, cultured meat may be even more detrimental than exclusive beef production (Lynch and Pierrehumbert 2019 <sup>[[#fn:r867|867]]</sup> ).

Overall, as argued by Stephens et al. (2018) <sup>[[#fn:r868|868]]</sup> , cultured meat is an ‘as-yet undefined ontological object’ and, although marketing targets people who appreciate meat but are concerned with animal welfare and environmental impacts, its market is largely unknown (Bhat et al. 2015 and Slade 2018 <sup>[[#fn:r869|869]]</sup> ). In this context it will face the competition of imitation meat (meat analogues from vegetal protein) and insect-derived products, which have been evaluated as more environmentally friendly (Alexander et al. 2017 <sup>[[#fn:r870|870]]</sup> ) and it may be considered as being an option for a limited resource world, rather than a mainstream solution. Besides, as the commercial production process is still largely undefined, its actual contribution to climate change mitigation and food security is largely uncertain and challenges are not negligible. Finally, it is important to understand the systemic nature of these challenges and evaluate their social impacts on rural populations due to transforming animal agriculture into an industrialised activity and its possible rebound effects on food security, which are still understudied in the literature.

Studies are needed to improve quantification of mitigation options for supply chain activities.

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