Table 3.
Total US food-related GHGE after hypothetical changes in meat intake among potential changers
|
Mean per person per day (n=7188) |
Population-level impact per day* |
||||||
|---|---|---|---|---|---|---|---|
| Mean (kg CO2-eq) | Mean change (kg CO2-eq)† | Change (%)‡ | Total (metric tonnes CO2-eq) | Change in total (metric tonnes CO2-eq) | Equivalent difference in passenger vehicle km§ | ||
| Original diet | 4·64 (4·48 to 4·80) | .. | .. | 475 410 | .. | .. | |
| 100% beef replaced | |||||||
| With poultry | 4·41 (4·27 to 4·55) | −0·22 (−0·26 to −0·19) | −4·8 | 452 471 | −22 939 | −90 484 398 | |
| With plant protein¶ | 4·39 (4·25 to 4·53) | −0·25 (−0·29 to −0·21) | −5·4 | 449 504 | −25 906 | −102 187 126 | |
| 50% beef replaced | |||||||
| With poultry | 4·53 (4·39 to 4·67) | −0·11 (−0·13 to −0·09) | −2·4 | 463 941 | −11 469 | −45 242 199 | |
| With plant protein¶ | 4·51 (4·37 to 4·65) | −0·13 (−0·15 to −0·11) | −2·7 | 462 457 | −12 953 | −51 093 563 | |
| 25% beef replaced | |||||||
| With poultry | 4·58 (4·46 to 4·70) | −0·06 (−0·07 to −0·05) | −1·2 | 469 676 | −5734 | −22 621 099 | |
| With plant protein¶ | 4·56 (4·42 to 4·70) | −0·06 (−0·07 to −0·05) | −1·4 | 468 934 | −6476 | −25 546 782 | |
| 100% beef, pork, or poultry replaced with plant protein¶ | 4·33 (4·19 to 4·47) | −0·31 (−0·35 to −0·27) | −6·7 | 443 494 | −31 916 | −125 891 484 | |
| 50% beef, pork, or poultry replaced with plant protein¶ | 4·48 (4·34 to 4·62) | −0·16 (−0·18 to −0·13) | −3·4 | 459 452 | −15 958 | −62 945 742 | |
| 25% beef, pork, or poultry replaced with plant protein¶ | 4·56 (4·42 to 4·70) | −0·08 (−0·09 to −0·07) | −1·6 | 467 431 | −7979 | −31 472 871 | |
Data are mean (95% CI), unless specified otherwise; all analyses account for survey design and sampling weights. Potential changers (n=1026) are individuals who reported trying dietary guidance and were estimated to be likely to agree that humans contribute to climate change; these individuals comprised 16% (95% CI 15–17) of the sample. All replacements were made in equal calorie amounts, as estimated from the National Nutrient Database for Standard Reference. Replacements were only made if individuals consumed the meats in question: 645 (61%) ate beef and 938 (92%) ate beef, pork, or poultry. GHGE=greenhouse gas emissions. NHANES=US National Health and Nutrition Examination Survey. CO2-eq=CO2-equivalents.
Population-level values were calculated by use of the probability weights (expansion factors) supplied with the NHANES dataset; these represent the size of the population at the midpoint of the survey years being used; in the case of NHANES 2007–10, this was 153 731 402 individuals.
A paired t test was used to test the hypothesis that the mean difference between individuals' substituted diets and original diets was equal to 0; all differences in the table were significant at a level of p<0·0001.
Values are percent change in the mean value compared with that of baseline (original).
Calculated with the US Environmental Protection Agency's Greenhouse Gas Equivalencies Calculator.
Plant proteins are legumes, nuts, and seeds; diet changes for each potential changer reflected the individual's actual reported intakes of these three food groups; replacements were made in the same ratio as that the individual reported eating the three food groups; if the individual did not eat any of the food groups, the overall average ratio in the sample was used to distribute the new intake, specifically 0·405 for legumes other than soy, 0·336 for nuts or seeds, and 0·259 for soy.