Mythbust: Dietary Changes to Save the World

Image result for beef emissions image


Every now and then, a fresh new research article comes out saying that if only people became vegetarian, or stopped eating beef, or ate more beans, that we’d take care of climate change.  Granted, agriculture and cattle production do have emissions associated with them and we need reductions everywhere we can get them.  Further, the IPCC (International Panel on Climate Change: the hyperlink is to its chapter on Agriculture, a pdf download) warns that large increases in meat consumption, especially of the middle class in China, will increase global emissions by as much as a few percent.

So, the latest such article is in The Atlantic, “If Everyone Ate Beans Instead of Beef” by James Hamblin with the tagline or summary “With one dietary change, the U.S. could almost meet greenhouse-gas emission goals.”  It summarizes a paper by Helen Harwatt and others that makes this argument.

This sounds amazing!  I didn’t know it was so easy!  (Even though it’s really hard to get 300 million people to change their diet.)

But more important, how accurate is this?  It turns out that the tagline is true, but the greenhouse-gas emissions goals it references are so weak this doesn’t turn out to mean much.

Here are a couple of key questions which really reveal that the devil is in the details:

  1. What or which climate goals are these?  The article references Obama’s climate goals for 2020 and says that this dietary change will get us 46% to 74% of the way there.  So what were Obama’s climate goals, how ambitious were they, and therefore how large or significant is a 46% to 74% step to those goals?
  2. How do these emissions due to beef compare to emissions due to fossil fuels?  While all reductions in emissions are great, do we need to focus on creating policies that meaningfully curtail beef production or, for instance, that curtail fossil fuel production and use?  If we answer “both”, what practical steps do we take?

Obama’s Climate Goals
The 2020 Obama pledge is a pledge that he made at the 2009 Copenhagen conference, which was that emissions would be 17% lower in 2020 than in 2005.  The graphic below which visually shows this is from the Climate Action Tracker webpage for the US: the 2 black, round circles in 2020 column, which the first vertical band of colors.  These black dots are located right about at the transition from the red color to the yellow color.  The red color means that emission reduction efforts are absolutely inadequate, yellow that they are medium (not adequate but not completely awful), green that they are adequate, and dark green means that emission reduction efforts are a role model for the world.

These particular climate goals mentioned by the article are completely insufficient.  Further, this report came out in 2017 when emissions are lower than in 2005 (as seen in the article), mostly due to some energy efficiency and the switch from coal to natural gas.  So getting us now from our current emissions to our 2020 emissions goals represents a change in emissions from about 6800 MT eq (metric tons equivalent, which already factors in the fact that methane and other gases are more potent than carbon dioxide) to about 6200 MT eq.  This is a decrease of about 10% in overall emissions, and so if every American stopped eating beef and ate beans instead, we’d get about 46% to 74% of that 10% decrease.  In other words, this colossal dietary switch would reduce our overall emissions by about 5 to 7% overall.

I would celebrate such a reduction for sure, but it’s not the smoking gun or amazing progress the article makes it sound like, huh?  Plenty of people are taking this to mean that if we made this dietary change, we would meet some super aggressive climate goals or would be 60% of the way toward truly doing the US’s part in stopping climate change.  Not so.

Emissions compared to fossil fuels
The true culprit in climate change is fossil fuels.  The US EPA reports the breakdown of US greenhouse gases by economic sector in 2015 in the pie chart below.  Again, this is in units of equivalent emissions, which already factors in the effects of the stronger potency of gases such as methane (CH4) compared to carbon dioxide (CO2).

Pie chart of total U.S. greenhouse gas emissions by economic sector in 2015. 29 percent is from electricity, 27 percent is from transportation, 21 percent is from industry, 12 percent is from commercial and residential, and 9 percent is from agriculture.

Total Emissions in 2015 = 6,587 Million Metric Tons of CO2 equivalent

Almost all of the remaining 91% of the emissions from electricity, industry, transportation, and commercial/residential are from fossil fuels.  So agriculture represents about half the emissions of any one of these categories, but the rest of the categories are linked by having fossil fuels as the root cause.  So clearly, doing something about fossil fuels would be drastically more important and effective than doing something about diet.  (Not to say that doing something about diet isn’t good: I eat very little meat, but this alone isn’t going to solve climate change!)

I applaud anyone who changes their diet for health and/or climate reasons.  Eating less meat helps with both.  But the first graphic shows just how deep our emissions reductions need to be to truly tackle climate change.  We need to be talking much more about that, and way to curb fossil fuels that are politically feasible in this country, such as a revenue neutral carbon fee with rebate, which would create 2.8 million jobs and decrease emissions 50% from 1990 levels within 20 years.

It gets confusing how people reference different years as reference levels, but looking at the first graph we can get a sense of it.  1990 levels were about 6200 metric tons (eek!  we are currently above 1990 levels in 2017!), while 2005 levels were about 7100 metric tons.  So a 50% reduction from 1990 levels within 20 years would have us at about 3000 metric tons of emissions.  Holy cow, what a real step forward!

The good news is that with some political activism and education, this carbon fee is politically feasible because it grows the economy, is not a tax because revenues are returned to households as a rebate, and does not grow the government because the government doesn’t keep the revenue.  Groups like Citizens Climate Lobby are working to educate the public and convince Congress to pass this law, which is simple and is only a few pages long.  Some major gas companies even support the concept in general, as a type of carbon action that is fair and transparent.

We all are passionate about different topics, but if we are serious about wanting to slow or stop climate change, we’ve got to figure out a practical way to curtail fossil fuel use economy-wide!

I worry about articles that make it seem like diet or some other quick fix (which is still quite difficult) will do it.  What does this type of misinformation serve to do?  Divide the climate activist community on the best path forward?  Help people feel proud of themselves for changes they will or already made (becoming vegetarian)?  Distract from the main cause, which is fossil fuels?  Make climate activists seem elitist or disconnected, focusing on peoples’ personal eating habits?  What do you think?  Why might these ideas about diet seem to be so popular and eagerly believed?

As always, I welcome your comments!