Changing your Diet Could Have Huge Land Use and Greenhouse Gas Implications

We all have within our power an incredibly effective way of reducing our planetary impacts:  embarking on your sustainability diet pathway. The concept is quite simple. Every person needs to take stock of their current diet and better understand two things: firstly, what impacts do your foody habits have on the planet; and secondly, what can you change in your diet to significantly reduce your food induced environmental footprint.

To illustrate the diet direction that we all ought to consider, I rely on a recent study that modelled our planetary impacts in the year 2050 with the very important assumption that our human population reaches nine billion inhabitants. The authors of this study simulate a planetary ecosystem and economy where the entire human population of Earth is on one of the following five diet variants as listed here:

  1. A reference diet, meaning our business-as-usual recent diet trends which encapsulate the good, the bad and the ugly of our regionally diverse, highly inequitable and majority high meat content that our diets have become.
  2. A ‘Healthy Diet’, as defined by the Harvard Medical School. This diet allows you to consume all meat sources (avoiding processed meats) in moderation while the bulk of your calorific intake should consist of fruits and vegetables. The Healthy Diet, and subsequent diets below, emphasize the need to eat in moderation avoiding any excessive over-eating habits.
  3. A no ruminant diet, is quite similar to the Healthy Diet only now no ruminant based meat (e.g. beef,  goat, sheep, buffalo) is allowed in your diet.
  4. A no meat (i.e. vegetarian) diet, where only dairy based animal products are permitted in your diet.
  5. A no animal (i.e. vegan) diet, meaning only plant/fungi based foods are permitted.

This study, entitled ‘Climate benefits of changing diet’, ensured that with the reference alternatives, every one of the nine billion human beings on the planet projected in 2050 would be nourished in a healthy and equitable fashion. Therefore, the reference alternatives (diet variants 2-5 above) would lead to a much healthier global population than our currently unbalanced food system. These four diet variants (2-5) can be seen as a sustainability diet pathway to embark upon, because in the equivalent order that these diets are presented above, they lead progressively towards less environmental impacts. The results from this study are actually quite amazing and I’ve illustrated the main findings in this short video below (please share!).

Certainly the models used to generate these astounding results require simplifying a great number of assumptions. However, the models utilized are among the best global integrated assessment models available in the world relying on years of research and refinement. The authors also undertook a number of sensitivity analyses to ensure their main findings were robust. Even if these findings are half the magnitude as they were presented, there is still ample justification to assume that these four diet variants progressively achieve less planetary impact in the proposed order as listed above.  Therefore, these diet variants provide us with an easy rule of thumb to follow if we wish to strive to achieve a diet that is considerably better for the planet.

Some of you may also be wondering what about fish? Although fish consumption was not modeled in any of the reference alternatives, this high protein meat sources generally has a life cycle environmental impact falling somewhere between chicken and pulses (like soy). (see above video for further context). However, as with most complicated systems in life, the devil is in the details. If your fish is flown halfway around the globe before landing on your plate, impacts can sky rocket towards similar greenhouse gas emission per unit protein as beef sources. So beware! The eat local mantra should be practiced to the best of your ability.

Back to those devils in the details: what major limitations do you feel need to be addressed in such an analysis? We’d all be thankful to hear your words of insight, caution, or skepticism.