Eating our way out of environmental change

Agriculture has a dramatic impact on our environment – humans have covered Earth in cropland to feed ourselves or to feed our food. As a result, there has been widespread deforestation, fossil fuel consumption and pollution to feed the planet. And given that human population size is increasing, the problem of feeding everyone and pollution in our environment will only become more pressing. At the same time food consumption is converging on a diet higher in meat and empty calories, which puts a strain on arable land and increases greenhouse gas production (see “Humanity is but an anchovy, from a food point of view” for information on human dietary trends and trophic level and “Eating Fewer Resources” for greenhouse gas emissions of meat products).

But is there a way out of it? Tilman and Clark (Tilman and Clark, Nature 515:518-522) investigated whether and how dietary changes of humanity could affect our impact on the planet in terms of greenhouse gas pollution and land use, as well as the effects on human health. They found that as wealth of countries increased over the past 50 years, demand for meat increased, while demand for legumes declined. At the same time, the proportion of the diet composed of ‘empty calories’ – foods which have few nutrients other than protein, fats and sugars – increased along with total calories consumed, which means that an increasing proportion of our agricultural land is being used to produce nutritionally-poor, as well as excess, food.

These trends in global diets are related to a rise in diseases such as cancer, obesity, type II diabetes, and heart disease. Tilman and Clark then compared how three diets (vegetarian, pescetarian, and Mediterranean) affect disease and death risk – these diets lead to a reduction in heart disease of at least 20%, cancer by ~10%, and type II diabetes by upwards of 41%. These diets were associated with greater vegetable consumption and fewer calories. So these dietary shifts are good for our health, but what are their effects on the environment?

If global food consumption switched to one of the above diets, greenhouse gas emissions would be reduced by at least 30% per person, and there would be no net increase in worldwide food-related greenhouse gas emissions despite a larger population. In contrast, the business as usual scenario would increase greenhouse gas emissions by 80%! Meanwhile total cropland would remain relatively unchanged, even if global population increases by 36% as predicted.

So can we eat our way out of further environmental damage? Maybe, but we can at least reduce further damage and pollution with shift in our diet, while improving our health at the same time.

Stay safe and stay informed,
Joe