Food and Greenhouse Gases: Emissions Intensity of Nutrition Sources

Post written by C.Will

New research published in Nature Climate Change argues that reducing the number of ruminant livestock, especially cattle, could significantly reduce greenhouse gas (GHG) emissions.  They find the GHG emissions from ruminants are 19-48 times higher than emissions from high protein foods obtained from plants. This comparison is based on full life cycle analysis including both direct and indirect environmental effects from ‘farm to fork’ (enteric fermentation, manure, feed, fertilizer, processing, transportation and land-use change are considered).

This offers a compelling argument for significantly reducing our consumption of animal protein to reduce our GHG emissions. However, it is important to consider the nutritional differences between animal protein and high protein foods obtained from plants.

A previous blog of ours discussed studies that look into the debate about GHG emissions from animal protein products and the nutritional difference between animal protein and other high protein sources. To get a comparable amount of energy from fruit and vegetables, larger portions are needed because animal protein products are a rich source of energy. Therefore, when comparing animal protein products and fruit and vegetables on a measure of GHG emissions per unit of energy (in kilocalories), the difference is much smaller.

The problem is complicated and the solution is not clear, but it is important to understand that the food choices we make as individuals do have an impact on the environment. Together we can improve the food security problem by making better informed decisions about our consumption.