Local foods good for the environment?

A couple months ago the journal Frontiers in Ecology and the Environment published a paper by Andrew Zumkehr and Elliott Campbell.  The paper was widely reported in the press.  For example the Washington Post the headline: As much as 90 percent of Americans could eat food grown within 100 miles of their home.  Another outlet: Most Americans could eat locally.  

I promptly wrote a blog post asking: even if Americans could eat locally, should they?  Shortly thereafter, I exchanged several emails with Pierre Desrochers, the author of the excellent book The Locavore's Dilemma: In Praise of the 10,000-mile Diet.  We decided a more formal reply was warranted.  

I'm pleased to report that a couple days ago Frontiers in Ecology and the Environment published a letter by Pierre and me.

We write:

“In a recent paper, Andrew Zumkehr and Elliott Campbell (2015; Front Ecol Environ 13[5]: 244–248) present a simulation study that assesses the technological feasibility of providing enough local calories to feed every American. In so doing, they suggest turning back the clock on one of Homo sapiens sapiens’ greatest evolutionary achievements: the ability to trade physical goods over increasingly longer distances, producing an attending ever-widening division of labor (Horan et al. 2005). The main benefit of this process is that one hundred people who specialize and engage in trade end up producing and consuming far more than one hundred times what any one individual would achieve on his or her own. By spontaneously relocating food production to regions with higher biotic potential for specific types of crops and livestock in order to optimize the overall use of resources, trade and the division of labor have delivered more output at lower costs.

Zumkehr and Campbell largely sidestep these benefits. They cite a few studies suggesting that (re)localized food systems would deliver environmental, economic, food security, and social benefits, but neglect to mention critiques of those claims”

We offer these specific critiques of their model:

“We also take issue with the authors’ use of yield data from each county to infer the agricultural potential of each location. This approach suffers from selectivity bias; the effect of increasing local food production onto more marginal local lands will likely deliver less-productive results than current average yields. In a competitive market economy, observed crop yields near urban locations are likely to represent an upper bound for the overall level of productivity in the area because only lands productive enough to outcompete other uses are currently devoted to agricultural production. The authors are also silent on the environmental consequences of removing wildlife from current idle lands to make room for domesticated plants and animals.

Moreover, the authors exclude cost considerations and conclude that the “current foodshed potential of most US cities is not limited by current agronomic capacity or demographics to any great extent”, but rather by “social and economic” considerations. However, an economic barrier is just as real and restrictive as an agronomic one. Resource and budget constraints simply will not allow all wants and desires to be realized. It is all very well telling people with limited means to eat local cake, but they should also be told of its price tag.”

What's good for countries is good for communities

A new paper by Trevor Tombe in the American Economic Journal: Macroeconomics provides a cautionary tale for those who think we'd be better off economically if we sourced more food closer to home.  

The paper starts off with this stylized fact

“Agriculture in poor countries has low productivity and high employment relative
to other sectors. Differences in aggregate productivity and income between
rich and poor countries are therefore primarily due to differences within agriculture;
Schultz (1953) calls this the Food Problem”

The problem, it seems, is that poor, agricultural-based countries don't trade.

“Trade data, though, presents a puzzle: with low relative agricultural
productivity, developing countries should be massive food importers; yet, they
are not (see section I.B). The “missing” food imports suggests trade costs may
be important for international productivity differences.”

These "trade costs" that are holding up trade include bad policies like tariffs but also bureaucratic problems like border delays.

The paper has a nice set graphs, and the following shows a few of them related specifically to agriculture.

First, when you don't trade agricultural products with you're neighbors, you tend to be poor.

Countries that have more agricultural trade have higher GDP/worker.  The correlation is 0.68.  Countries that have more agricultural trading partners tend to be richer and more productive.

A lot of local food advocacy is premised on the idea that we need smaller farms with more farmers.  I don't think anyone would argue that greater local food production would mean  more employment in agriculture.  Well, would that be good for the economy?  According to this paper, no. This graph shows a very clear negative correlation between a country's employment share in agriculture and GDP/worker.  More workers in agriculture is typically going to mean lower economic output.  

Finally, this graph shows that the higher the share of food spending on domestic output (i.e., the more local foods purchased), the lower the country's GDP/worker.   

There's no reason to believe what's true of countries wouldn't also be true for states or cities trading with each other.

The author concludes:

“Agricultural trade costs account for roughly 25 percent of the aggregate differences between rich and poor countries. Trade costs in agriculture and manufacturing together account for over 40 percent. Even observable, policy-relevant trade costs (tariffs and border
delays) have important negative productivity effects in poor countries. The food
trade is missing in poor countries and in our models; it should be no longer.”

Buying local good for the economy?

Here's a nice video by Don Boudreaux for MRUniversity on the myth that buying local is good for the economy.  Sometimes a picture (or in this case, video, is worth a 1,000 words). 

Local Foods on Stossel Show

Here's a slice of my interview with Stossel about local food that they released on YouTube (which I presume means this portion of the interview got cut from what will appear later tonight on Fox Business).  

Study Shows Most Americans Could Eat Locally, but Should They?

This paper in Frontiers of Ecology and Environment by Andrew Zumkehr and Elliott Campbell conducts a type of simulation to suggest that most Americans could eat locally (see the accompanying press release here).

That seems like the wrong question.  It shouldn't be whether we CAN eat locally but whether, WHY would you want to eat everything grown locally?  

The paper basically assumes local is "good" and asks how do we get more of it.  A few, uncritical references are made to the fact that local food systems may "result in large GHG emission reductions" or that it "shortens the distances required for economic and energy-efficient recycling of waste streams between farms and cities" or it " may increase community involvement in food production issues, potentially leading to improved environmental constraints on landuse practices."  Yet, there is good reason to believe that local food systems would generate more GHG emissions, result in less food choice and dietary diversity, increase price and availability risk for consumers, and drive up food costs.  There is a lot written on each of these issues, none of which is referenced here.

In any event, the authors do some calculations to suggest it may be technological feasible to provide enough calories to feed everyone in this country with local production.  The authors used yield data from each county in the US to infer the productivity of growing crops in each location.  However, it is likely a mistake to assume that yield would remain constant as production expands to more marginal lands.  In fact, it is almost certainly the case that observed yields near urban locations are an upper bound for the productivity in the area because only those lands that are currently productive enough to out compete other uses are those currently in use for crop production.  That is, you're only observing yield from the most productive lands and you're not observing yields from the least productive lands.

It might not be surprising to hear that the authors don't calculate the cost of all this.  The words "cost" and "price" appear exactly three times in the paper, the latter of which in reference to the fact that they don't study price effects.  The paper concludes that: 

“current foodshed potential of most US cities is not limited by current agronomic capacity or demographics to any great extent, and that the critical barriers to this transition will be social and economic.”

Saying the main barrier is "economic" is akin to saying the main barrier is reality.  The reality of the resource constraints that nature deals us and our willingness to pay to overcome some of those constrains.

Nonetheless, that doesn't keep them from proposing some grand plans .  From the press release: 

“Campbell’s maps suggest careful planning and policies are needed to protect farmland from suburbanization and encourage local farming for the future.”

I don't see anything in this paper that suggests we need "careful planning" or to "encourage local farming."  If people want local foods and are fully willing to pay for them, farmers will provide it.