1. Introduction
The agricultural sector is an important contributor to anthropogenic greenhouse gas emissions (GHGEs) [
1]. GHGEs from on-farm production and related land use changes account for about 20% to 25% of the total emissions from all human activities [
2]. This contribution is even more striking for non-CO
2 GHGEs. For example, crop and livestock production within the farm gate contribute more than 50% of the total anthropogenic methane (CH
4) and 75% of the nitrous oxide (N
2O) emissions [
3,
4]. Besides, emissions from pre-production, such as fertilizer and pesticide manufacturing, also increase these emissions. Hence, mitigating agricultural GHGEs has attracted wide public concern.
In addition to the mitigation strategies in food supply chains, dietary patterns are also critical to mitigating agricultural GHGEs through their impact on supply activities. Many studies have explored a series of approaches to reduce agricultural GHGEs from the supply side, such as technological innovation and production management [
1]. From another perspective, the food demand determines the food production, in regards to both quantities and structures, which is related to the agricultural GHGEs [
5,
6]. With economic development and population growth, the food demand is increasing, and the structures tend towards animal-based food [
7]. Especially in developing countries, the rapid per capita income growth has noticeably improved diets [
8]. Thus, it is interesting to study the changes in residents’ food demands and diet-related agricultural GHGEs over the past decades and project their responses to income growth and the increased prices of animal-based foods.
China is an interesting and important case in regards to this problem. First, China is a traditional agricultural country, which feeds about 20% of the global population. The agricultural GHGEs account for 17% (according to the Initial National Climate Change Bulletin of the People’s Republic of China) of the total anthropologic GHGEs in China, and the ratio is higher than the average global level [
3]. This study will help us explore how to reduce agricultural GHGEs from the demand side. Second, China is a populous country with enormous economic development; thus, the food demand has experienced significant changes in quantity and structure [
9,
10]. From 1987 to 2017, the diet-related GHGEs increased by 64%, driven by a more meat-intensive diet [
11]. Thus, estimating the food demand characteristics and projecting the changing trends is important for both food security and a sustainable environment. Last, to show responsibility for sustainable development, the Chinese government aims to achieve carbon peaking by 2030 and carbon neutrality by 2060. The result of this study will contribute to achieving the goals from the perspective of the food demand side.
A great deal of work has been done to evaluate diet-related GHGEs and propose strategies to reduce GHGEs. Previous studies have calculated the GHGEs from plant- and animal-based food [
12] and evaluated diet-related GHGEs at national [
11,
13,
14], provincial [
15], and household levels [
9,
16,
17]. Further, the driving factors, such as Engel’s coefficient, urban/rural status, and demographic factors of increased diet-related GHGEs, have been analyzed [
13,
14,
17]. Some studies also compared the current Chinese diet with Western diets or diets recommended by the Chinese Dietary Guidelines, simulating the future changes in diet-related GHGEs under different diet scenarios [
9,
18,
19]. These results showed that a healthier diet with less meat consumption can facilitate a reduction in agricultural GHGEs [
9,
18]. In this regard, some Western scholars suggested levying a carbon tax on animal-based foods, which can efficiently reduce diet-related GHGEs [
20,
21,
22]. However, few studies evaluated the impacts of income growth or a rise in food prices on diet-related GHGEs in China based on demand models. Based on previous studies, this study investigates the time-variable GHGEs from 2000 to 2020 and further examines the responses of food demands and diet-related GHGEs to an increase in per capita income and prices of various animal-based foods.
Many studies estimated food demand elasticities using demand models or meta-analysis, some of which further projected the food demands in the future. These results showed that income responsiveness was higher for meat consumption, and meat demand would continue to increase with income growth [
23,
24,
25]. However, the income elasticities of most foods tend to decline with income increases, while the own-price elasticities for some foods tend to be more elastic [
25,
26]. This means that bias between food demand projections based on dynamic income elasticities and results based on constant elasticities are substantial, and the bias will gradually increase over time [
26]. Hence, this study estimates the time-variable demand elasticities and performs the projections considering the dynamic demand elasticities as per capita income increases.
This study aims to estimate the dynamic changes of food demand elasticities with time-series data, and project the responses of food demands and diet-related agricultural GHGEs to an increase in per capita income and animal-based food prices. This study fills the gap in the literature by (1) projecting the impacts of a rise in income and animal-based food prices on diet-related GHGEs considering the change in demand elasticities; (2) analyzing the change trends in demand elasticities with time-series data. We employed the data from the China Statistical Yearbook (2001~2021) and divided the residents’ consumed foods into six groups. First, we clarified the food demand characteristics and related agricultural GHGEs from 2000 to 2020. Then, we used the Almost Ideal Demand System (AIDS) model to estimate the demand elasticities of six food groups and analyzed their dynamic changes. Last, we performed two projections. One is to simulate the impacts of income growth on food consumption and diet-related GHGEs considering the dynamic changes of income elasticities; the other is to project the responses of food consumption and diet-related GHGEs to an increase in prices of different animal-based foods.
The remainder of the paper is organized as follows.
Section 2 introduces the methodologies and data, including the conceptual framework, demand model, and calculations of diet-related agricultural GHGEs.
Section 3 presents the results.
Section 4 and
Section 5 discuss and conclude the study, respectively.
4. Discussion
Given the continued economic growth and diet transition, this study analyzed the time-variable demand elasticities and explored the responses of food demand and diet-related agricultural GHGEs to changes in per capita income and food prices. Consistent with the results of previous studies [
9,
35], we found that the share of animal-based food expenditure in the total food expenditure, quantities of animal-based food consumption, and diet-related GHGEs from animal-based foods showed an upward trend during the past two decades. For this, per capita income growth is the main driving factor, and demographic transition and urbanization also play a role [
13,
29,
36]. Although the consumption of beef and mutton is not much, the corresponding GHGEs are high and have become the highest among those from animal-based foods since 2015. The high carbon emission intensity of ruminant meat and the growing appetite for beef and mutton can explain this effect [
27,
37].
Our results show that income elasticities for most foods tend to decline, which are consistent with previous findings, although the exact elasticity values from various studies are different due to various data sources, food categories, and methods applied (
Appendix B). The changing trend of income elasticities agrees with our expectations. Moreover, our results reveal that own-price elasticities for vegetables and fruits; pork; beef and mutton; and poultry and eggs are more elastic as per capita income increases. However, Liu and Zhong [
38] showed that own-price elasticities for rice and flour became more sensitive to price changes over time. This may be because Liu and Zhong [
38] used samples from 1986 to 2002, during which time people were still searching to obtain enough calories instead of looking for diverse foods. One explanation for these increased price-elastic elasticities may be that the economic and market development provide consumers with more choices, more substitution possibilities, and price-elastic demand [
25]. Animal-based foods, especially beef and mutton, are more sensitive to income growth than plant-based foods. This result agrees with previous findings, which imply that animal-based food consumption will grow faster than plant-based food consumption as income increases [
39,
40]. Among all animal-based foods, aquatic product consumption is the most price-elastic, followed by beef and mutton consumption, and pork consumption. This indicates that policymakers might reduce GHGEs through food demand management by food price adjustment, while assuring residents’ nutrition intake.
Further, our projections show that the demand for all foods, except staple foods, will increase as per capita income increases. This is according to the finding of Zheng et al. [
41], who revealed that food security in China has been transformed into feed grain security. Further, the increased food demands decline with income growth due to the decreased income elasticities. Hence, the increased diet-related agricultural GHGEs also tend to decline, and may even be negative. Besides, if we increase the prices of beef and mutton, pork, and poultry and eggs and reduce the prices of aquatic products, the diet-related agricultural GHGEs can be noticeably reduced. This is according to Western research, which showed that imposing a tax on several animal-based foods can effectively mitigate GHGE [
22,
42]. However, as China is still a developing country, any policy aiming to reduce GHGEs should guarantee food security and residents’ nutrition intake. Hence, China may combine a tax and subsidy policy to promote a sustainable diet.
From the demand side, a single measure is also not enough to achieve carbon neutrality and mitigate the projected increase in environmental burden. In addition to improving diet, international trade and reducing food waste and food processing are also expected to deliver emission reductions [
5,
6,
43]. For example, Kong et al. found that if we decrease food waste and food processing by 10%, the total agricultural GHGEs can be reduced by 1.59% [
44].
There are several limitations in this study, which should be further addressed in the future. First, the heterogeneities of regional disparity and the urban-rural gap should be further analyzed. Second, the data from the China Statistical Yearbook only include residents’ food consumption at home, ignoring the food consumption away from home. As meat demand, especially beef consumption, away from home grows more than proportionally to total food consumption [
45], our result might underestimate diet-related GHGEs and their responses to an increase in income and animal-based food prices.
5. Conclusions
This study investigated diet-related agricultural GHGEs in China and their responses to an increase in per capita income and animal-based food prices. The AIDS model, considering the issue of food expenditure endogeneity, was used to estimate demand elasticities for six food groups from 2000 to 2020. Then, the impacts of an increase in per capita income on food demands and diet-related agricultural GHGEs are projected considering the trend in the changes in income elasticities. Meanwhile, we also projected the responses of diet-related agricultural GHGEs to an increase in the prices of pork, beef and mutton, poultry and eggs, and aquatic products, respectively.
Our results indicate that the food demand and diet-related agricultural GHGEs will increase in the short term, but the increased effect tends to decline gradually. In the long term, the total diet-related agricultural GHGEs might decrease due to a lower increase in animal-based food and a greater decrease in staple foods. The dominant driver of increased diet-related GHGEs is the increased consumption of beef and mutton and pork. However, increases in prices of beef and mutton, pork, and poultry and eggs can reduce diet-related agricultural GHGEs, while an increase in the price of aquatic products has the opposite effect.
Along with remarkable economic development, China is also facing environmental challenges. On the road to achieving carbon peaking and carbon neutrality, this study has important implications for policymakers. With the continued increase in per capita income, although diet transition improves residents’ nutritional status, the government should pay attention to the environmental impacts driven by the rapid increase in animal-based food demand. In addition to the mitigation strategies from the supply side, the government can reduce GHGEs through food demand management from the demand side, while ensuring residents’ nutritional intake, for example, by subsidizing low-carbon food or taxing carbon-intensive food to promote a more sustainable diet structure.