With 7.7 billion people on Earth  we have to produce a lot of food. Sadly, food production is a major source of greenhouse gas emissions [7,9,10] and the main cause of tropical deforestation . But we do need to eat! So what foods are better and worse for the planet?
Swipe across for a graph showing CO2e* emissions per 100 grams of protein of various food types . The lines span from the lowest 10% to the highest 10% of emissions for that food, indicating how emissions vary depending on how the food is made .
Keep in mind that different foods have different nutritional qualities . Root vegetables may cause very low CO2e emissions , but we can’t only eat root veg…
What can we learn from this? Fruit, vegetables, and cereals have very low emissions . The most efficient sources of protein are also plant-based ! Beef and lamb have comparably very high emissions  because cows and sheep burp lots of methane [9,10], a potent greenhouse gas .
Strikingly, chicken produces on average only 10% as much CO2e emissions as beef (per gram of protein) . More people eating chicken (instead of beef) would make more chickens suffer : farmed chickens often have very poor welfare [23,24]. For example, chickens may behave abnormally, be chronically hungry , or die from disease . On the other hand, it would save land from deforestation , saving wildlife , and reducing emissions .
Whilst it would be ideal if we all ate diets with a minimal environmental impact, including no meat , this is unlikely to happen . Therefore, if we all stopped eating red meat, this would be better for the planet than 10% of us going vegan.
*To measure the impact of different greenhouse gases in one unit, scientists invented “CO2 equivalent (CO2e)” . 1kg of methane emissions is 28kg CO2e
 Our calculations based on data S2 from Poore and Nemecek 2018: https://science.sciencemag.org/content/360/6392/987/tab-figures-data
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