Today an article by five co-authors and me was published in the journal Nature Climate Change. It’s on “Ruminants, climate change and climate policy,” and makes the point that political and business leaders concerned about global warming have missed an important part of the problem. This missing piece of the puzzle is the emissions – mostly of methane, a greenhouse gas that is 25 times as powerful as CO2 – that come from ruminant livestock, which include sheep, goats, water buffalo, and most importantly cattle.
Reducing the emissions from ruminants, which are mostly associated with the production of beef, could make a big contribution to preventing the worst impacts of global warming. But what’s the alternative?
This graph — my modification of Figure 2 of our new paper, which shows the emissions associated with different kinds of food — shows how much greater the emissions of beef are, compared to the alternatives. The emissions associated with meat from ruminants (red bars) are all much higher than the other sources of protein (blue bars).
Emissions from different sources of animal and plant protein, in kg CO2eq per kg of product.
Horizontal lines added by Doug Boucher to indicate mean values for beef (red line), pork (blue), poultry (green) and plant sources (purple). Source: Figure 2 from Ripple et al 2014, Nature Climate Change; original data from Nijdam et al. 2012, Food Policy.
What’s most notable is how close to each other – and to zero – the three main alternatives are, compared to the great difference between any of them and beef. In other words, if you want to reduce the emissions associated with the food you eat, the most important step is to reduce your consumption of beef. Compared to that decision, the question of what you replace it with — pork, poultry, or plants only — is much less important.
This comparison can be put into numbers, using the means for pork, poultry, and plants and comparing them to the three different beef production systems and their overall mean. Naturally the biggest reduction comes from replacing beef with plant foods. But the reductions made by moving from beef to chicken are all at least 90 percent as large as the beef-to-plants change. (They range from 92 to 97 percent, depending on the production system of the beef that you started with.)
For switching from beef to pork, the reductions are a bit less but still all at least 80 percent of that achieved by going from beef to plant protein (ranging from 82 to 93 percent).
There are other considerations besides climate footprint that are relevant to the sustainability of kinds of food, of course. We have shown that the alternatives to beef are preferable to it in terms of land use and health impacts, for example, in our recent report on Climate-Friendly Land Use. (I should point out that by “we” I mean me and my UCS colleagues, not the co-authors of the new paper, who may or may not agree with this post.) And of course there are important economic and social questions involved as well. But if Earth’s climate is your main concern, the lesson is pretty clear: the important point is to eat less beef, no matter what you replace it with.
And in that spirit, here’s a Christmas turkey, with best wishes for Happy Holidays and a climate-friendly New Year.
Turkey dinner. Source: texascooking, Flickr.com