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Effects of diet overstated

Posted by martijnkatan on 23 Oct 2017 at 19:24 GMT

This is a valuable paper, but the Abstract and the first line of the Discussion vastly overstate the potential benefits of diet. The paper finds reductions in GHG emissions, water use etc. of 20-25% not 70-80%. The authors correctly summarize their findings as: 'The median changes in GHG emissions, land use, and water use, across all sustainable diet types, were -22%, -28%, and -18%, respectively’. The claimed 'reductions as high as 70-80% of GHG emissions’ in the Abstract and 'reductions above 70% of GHG emissions’ at the start of the Discussion are never substantiated or even mentioned in their Results. These numbers probably derive from the –72% in Bryngelsson et al. (2016), which is only one out of the 124 studies reviewed. Another vegan study actually found an increase in water use of +107% (Fig. 4). We should ignore both these outliers.

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