In order to attain carbon neutrality, large-scale deployment of bioenergy with carbon capture and storage (BECCS) is imperative, as indicated by numerous integrated assessment models1,2. BECCS is particularly notable for its capacity to remove carbon dioxide and replace polluting fossil fuels. However, concerns have been raised regarding the substantial land, water and nutrient requirements associated with BECCS3. Widespread implementation of BECCS may impact food production4 — particulary in countries such as China, which must feed 20% of the global population with only 7% of the arable land. As the world’s largest carbon emitter, China must urgently address the question of how to produce sufficient bioenergy to achieve carbon neutrality targets without compromising food security and other land-based sustainability objectives.
Credit: mustbeyou / Alamy Stock PhotoNow writing in Nature Food, Ren et al.5 find that an efficient food system can be an effective solution to address thisissue. This efficient food system includes three sustainable measures: (1) closing the yield gap by adapting recommended practices without increasing nitrogen fertilizer use, (2) reducing food loss and waste, and (3) shifting toward healthier diets that align with dietary guidelines. Under this efficient food system, although more than 50 million hectares of cropland are required to meet the carbon neutrality target in 2060, China can still achieve its food security target, with average aily per-capita calorie intake increasing from 2,905 kcal in the reference scenario (the ‘middle of the road’ pathway) to 3,294 kcal in 2060. Additionally, the implementation of this efficient food system will also alleviate environmental burdens in China by reducing agricultural land, irrigation water, nitrogen fertilizer and greenhouse gas emissions by 21% (53 million hectares), 13% (48 km3), 17% (4 million tonnes) and 12% (44 million tonnes CO2 equivalent), respectively.Previous global studies have ued stylized assumptions to investigate the above measures, however several regional differences should be incorporated into integrated assessment models for more realistic results and targeted advice. For example, China has set minimum 95% self-sufficiency rates (SSR) for three main staple crops — namely wheat, rice and corn — as well as guidelines, policies and laws to promote healthy diets and reduce food waste and loss. Another point of attention is the interregional transfer of envionmental burden through trade. The work of Ren et al. therefore builds a valuable bridge between the top-down integrated assessment model (GLOBIOM-China) and bottom-up national studies by examining country-specific policies on food, trade, resources and the environment.The present study makes a very bold assumption: removing China’s 95% SSR to explore what would happen if the country’s food demand were to be met through trade. Results show that, without an efficient food system, wheat self-sufficiency wold decrease to 66% by 2060. Additionally, food imports would pose negative environmental impacts onto trading partners, requiring an additional 23.2 million hectares of agricultural land, 16.6 km3 of irrigation water and 1.7 million tonnes of nitrogen fertilizer, while generating 46.2 million tonnes CO2 equivalent of greenhouse gas emissions (from agriculture, forestry and other land use). Therefore, without an efficient food system, using trade to solve the domestic food shortage causd by bioenergy deployment under the carbon neutrality target would compromise domestic food security and global sustainability.However, the transition to an efficient food system can effectively convert these trade-offs into synergies. To prove the robustness of their findings, the authors undertook multiple sensitivity analyses, including ‘one-at-a-time’ and ‘two-at-a-time’. They found that, under all the variants of efficient food systems, SSR for both rice and corn could be robustly higher than 95% (tht is, 95–100% and 97–99%, respectively). Compared with the reference scenario that sets aside carbon neutrality and other land-based sustainable development targets, six sustainability indicators for China (calorie intake, water demand, greenhouse gases, fertilizer uses, agricultural land, food price) and four virtually imported environmental impacts from trading partners (virtual greenhouse gases, virtual nitrogen, virtual water, virtual agricultural land) show substantial improvemens, underscoring that efficient food systems are essential for achieving carbon neutrality, food security and global sustainability simultaneously.Ren et al.’s study assumes that China’s carbon neutrality may require large-scale bioenergy deployment. Future studies should make this assumption more carefully, as its practical potential has long been discussed and even questioned6. Many other carbon removal technologies, such as afforestation, direct air capture, biochar and enhanced weathering, can also be icluded in the model’s portfolio of technologies, thereby reducing the demand for BECCS and land competition with food production7,8. Moreover, an efficient food system itself could also be an important mitigation measure. Future studies can explore another storyline — an efficient food system may reduce greenhouse gas emissions, decrease the ‘negative’ emissions demand sourced from BECCS, and thereby reduce land pressure and increase food security. Last but not least, the realizationof an efficient food system may face social, economic, environmental and cultural challenges — for example, how to ensure people of different ages and socioeconomic statuses have appropriate animal-based food and calorie intake9, and how to increase food production without incurring additional environmental burdens10.Food systems are closely related to multiple sectors and sustainability targets. The work of Ren et al. makes it clear that the threefold goals of carbon neutrality, food security and global sutainability depend on the careful design of efficient food systems, while also identifying solutions that can convert possible trade-offs between climate mitigation and sustainable development into synergies.
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Download referencesAcknowledgementsThis work is jointly supported by the National Natural Science Foundation of China (72140002) and the Tsinghua-Rio Tinto Joint Research Center for Resource Energy and Sustainable Development.Author informationAuhors and AffiliationsDepartment of Earth System Science, Institute for Global Change Studies, Ministry of Education Ecological Field Station for East Asian Migratory Birds, Tsinghua University, Beijing, ChinaWenjia Cai, Rui Wang & Shihui ZhangAuthorsWenjia CaiView author publicationsYou can also search for this author in
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