How to cut global food emissions by two-thirds – by going vegetarian

A post at Sciblogs argues that going vegetarian could drastically reduce our carbon footprint at a personal level. But what happens when you multiply such changes by 7 billion people and factor in a growing population?

The answer is provided by Marco Springmann, a researcher at University of Oxford

In our latest research, colleagues and I estimate that changes towards more plant-based diets in line with the WHO’s global dietary guidelines could avert 5m-8m deaths per year by 2050. This represents a 6-10% reduction in global mortality.

Food-related greenhouse gas emissions would also be cut by more than two-thirds. In all, these dietary changes would have a value to society of more than US$1 trillion – even as much as US$30 trillion. That’s up to a tenth of the likely global GDP in 2050. Our results are published in the journal PNAS.

Future projections of diets paint a grim picture. Fruit and vegetable consumption is expected to increase, but so is red meat consumption and the number of calories eaten in general. Of the 105 world regions included in our study, fewer than a third are on course to meet dietary recommendations.

A bigger population, eating a worse diet, means that by 2050 food-related GHG emissions will take up half of the “emissions budget” the world has for limiting global warming to less than 2℃.

To see how dietary changes could avert such a doom and gloom scenario, the researchers constructed four alternative diets and analysed their health and environmental impacts: one reference scenario based on projections of diets in 2050; a scenario based on global dietary guidelines which includes minimum amounts of fruits and vegetables, and limits to the amount of red meat, sugar, and total calories; and two vegetarian scenarios, one including eggs and dairy (lacto-ovo vegetarian), and the other completely plant-based (vegan).

They found that adoption of global dietary guidelines could result in 5.1m avoided deaths per year in 2050. Vegetarian and vegan diets could result in 7.3m and 8.1m avoided deaths respectively. About half of this was thanks to eating less red meat. The other half came from eating more fruit and veg, along with a reduction in total energy intake (and the associated decreases in obesity).

There are huge regional variations. About two-thirds of the health benefits of dietary change are projected to occur in developing countries, in particular in East Asia and South Asia. But high-income countries closely follow, and the per-person benefits in developed countries could actually be twice as large as those in developing countries as their relatively more imbalanced diets leave greater room for improvement.

There are production implications too.

Fruit and vegetable production and consumption would need to more than double in Sub-Saharan Africa and South Asia just to meet global dietary recommendations, whereas red meat consumption would need to be halved globally, and cut by two-thirds in richer countries. We’d also need to tackle the key problem of overconsumption.

It’s a lot to chew on, Springmann concludes.

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