Sunday, August 26, 2007

The "Eco-Footprint" and the productivity and efficiency of land use

This posting in response to a small portion of Oskar's Orientation. The new blog entry is necessary to post images, and this is going to be quite long anyway, so please forgive its displacement from the comments section.

In response to the chart of relative Eco-footprints, George questioned the role of productivity differences between countries. Oskar's response in the Orientation post was somewhat speculative, so I thought I'd take a look at some data. While I don't think George was referring to agricultural productivity alone, agriculture is the most land-intensive human activity, and the Eco-footprint is cast in terms of hectares of land, so I'll follow Oskar in looking at arable land use, specifically the production of food crops, for which there's reasonable cross-country data available from the UN's Food and Agriculture Organization. I'll be using their year 2000 numbers, which are more complete than some of the more recent data.

The FAO breaks production of food crops into three groups, cereals, pulses (peas, beans, and lentils), and roots/tubers. The distribution of these three crop types is heterogeneous across the globe, with North America specializing the production of cereals, which account for over 90% of the mass of food crops produced. Roots and tubers become more prevalent moving from NA to Asia, then Europe, Latin America, and finally Africa, where they make up the bulk of food crop production. Pulses constitute only a small portion of production on a continent-level basis, but they do contribute a significant amount in many individual countries. In general, I'll handle this heterogeneity by considering the total mass of food produced, assuming geography determines which crops are produced but that, all else equal, the inherent productivity of land in terms of mass of food per hectare is equal.

This first figure results (click to enlarge). The total mass of food crops divided by the land area used to produced them is displayed for selected countries (those in the Eco-footprint chart and a few others of interest), ranked high to low from left to right as in the Eco-footprint chart, with the world average on the far right. While agricultural land in the US is much more productive than the average plot of land in the world, it is not the most productive, significantly no different than the average plot of land in China.

One potential explanation for the higher average productivity of land in the UK, Germany, Japan, and South Korea is the higher population density of these heavily industrialized countries. Economic theory would predict that as the total area of farmland is reduced, the least productive farmland will be recruited to other uses first, thereby raising the average productivity of remaining farmland. When a dwarf leaves a room, the average height of the remaining people goes up without anyone actually growing taller. This effect should be testable with the FAO's data over time, but that's outside the scope of this simplistic cross-country comparison.

Instead, I'll follow Oskar's lead and take a look at the inputs that are put into this productivity. Farmland in the US and China might be equally productive in a gross sense, but we need to consider net productivity. The next set of figures do just that. The most important input to agriculture, as mentioned, is land, so we can get an idea of the efficiency (or lack thereof) of land use by simply taking the inverse of the preceding graph: the amount of land (hectares) it took to produce a given amount (100 tonnes) of food in each country. Countries are ranked by how inefficiently they use the input, making the UK the most efficient at the bottom of the chart while Australia, with its wide, dry spaces is the most land-intensive producer among the selected countries. As you can see, the US uses land more efficiently to produce food crops than the world at large.

While the FAO doesn't have usable data on pesticide use, it does for fertilizer. As indicated in the chart below, the US used slightly more fertilizer to produce a given amount of food than the world average, but is much more efficient with this input than many industrialized and industrializing countries, including China. The intense use of fertilizers in South Korea and Japan may help explain their productivity advantage over the US, but at greater environmental cost. Nigeria stands out as the most 'efficient' user of fertilizers, barely using any to produce mostly tubers.

Next up is water used for irrigation. The scale of the chart is distorted by the extremely inefficient irrigation that occurred in Bangladesh, over 250 thousand cubic meters of water to grow 100 tonnes of food, while the average plot of farmland in that country was about at the world average. Japan also used exorbitant amounts of irrigation, which unlike Bangladesh helps contribute to relatively high productivity. Contrast Japan to the UK, which achieved the highest agricultural productivity per unit land with negligible irrigation--the most water-efficient of the selected countries. While China sat at about the world average for agricultural water use, the US used significantly less water to achieve the same land productivity.

The large-scale use of industrial machinery and its intendant fossil fuel consumption and resulting emissions is the largest component of the high Eco-footprint of Americans. How does this shape up for agricultural production? The next figure displays the number of tractors on average used to produce 100 tonnes of food crops. Japan far exceeds the other selected countries and the world average here, heavily distorting the scale of the chart. Surprisingly, the US was below the world average in 2000, and used significantly fewer tractors on average to produce the same amount of food than most other industrialized countries in our comparison. For the first time, China is more 'efficient' than the US, relying on fewer tractors to farm the same amount of food.

The final input under consideration is labor. As seen the the chart below, the Southeast Asian countries relied on huge amounts of labor to produce food crops, India over 90 workers per 100 tonnes, while the UK and her former colonies used stunningly little labor, less than one worker in American fields to achieve the same production as 90 or so Indians, Bangladeshis, or Chinese. China and India alone contributed about 58% of the world's agricultural labor force in 2000, making them the prime drivers of the high world average.

Agricultural labor is even more interesting in the inverse. The mass of food on average produced by each farmworker is displayed in the final chart. Canadian farmworkers were the most productive, yielding an astonishing average of over 150 tonnes of food crops each, with the US slightly behind at about 122 tonnes/worker. The average Indian, in contrast, produced just 1 tonne of food in the year 2000, with many of the countries in our selection faring only slightly better. This indicates those huge masses of workers in Southeast Asia are primarily engaged in subsistence-level farming. Japanese workers produced just over 6 tonnes of food each on average.

It's interesting to compare the US to Mexico, where workers produced an average of only 3.6 tonnes of food each in 2000. Farm workers in the US were over 30 times more productive than those south of the border. Are Americans workers simply more productive than Mexicans, all else equal? This is clearly not the case, since the majority of the 3 million American workers in 2000 were Mexican nationals, legal and illegal. Mexicans are vastly more productive in America than they are in Mexico.

Why the difference? As we've seen, in addition to the relatively negligible amount of labor, American agriculture used less land, fewer tractors, and vastly smaller amounts of land and water to produce a given amount of food than most of the countries in our comparison and the world as a whole, with only slightly more fertilizer per unit of food. This is the result of technology, by which I mean the way the different factor inputs are used together to produce an output. American farms simply make better use of the resources put into farming, including, most spectacularly, people. Overall, the performance of agriculture in the US seems quite good under this comparison.

Japan's productivity, on the other hand, was based on extremely intensive use of fertilizer, tractors, and, for an industrialized country, labor, allowing it to get more food out of more limited land resources. But Japan's gross productivity wasn't that much higher than the US given its increased resource use, such that Japan may very well have much lower net agricultural productivity than the US. Unlike Japan, the UK made limited land more productive with much lower costs in terms of water, labor, and fertilizer, though they needed more tractors on average to do so.

So why do we Americans have such a huge Eco-footprint if we're doing relatively well in terms of agricultural land use? Part of the reason lies in the sheer scale of American activity. In 2000, the US produced over 30% more tonnage of food crops than India, using only 3 million farm workers compared to India's 263 million strong agricultural labor force. Only China, with its 511 million farm workers produced more food than the US. Only China and India farmed more hectares of land than the US. Only China used more total fertilizers, with the US using 12.5% more than the third largest consumer of fertilizers, India. But while both China and India have large-scale agriculture in the same league as the US, over 17% of the world's tractors were employed in America--nearly 4.7 million of them. India made use of just under 2 million tractors, while China used just under 1 million.

The Eco-footprint simply weighs several million tractors as far more harmful to the ecosphere than three quarters of a billion subsistence farmers. Whether this is a fair weighting is open to debate.

Finally, instead of asking "how many Earths"-style questions inspired by the Eco-footprint, we can ask what global agriculture would look like if every country employed American agricultural technology, all else being equal. This will require the assumption that corn fields in Africa are just as inherently productive as those in Kansas, potato fields in Canada just as inherently productive as those in Idaho; it's the use of input factors that matter.

Running the numbers, in the year 2000, each of the 161 countries in my data set could have produced the same amount of cereals, pulses, and roots/tubers at US levels of efficiency (or inefficiency) with a small, about 6.4%, increase in global fertilizer use along with more 33% more intensive use of tractors (that's an additional 8.8 million of these machines). What would be gained from such increases? First, such American-style production would have reduced global water use for irrigation in 2000 by more than 63%, a savings of nearly 870 billion cubic meters of fresh water. It would have required 50% less land under the till, freeing up nearly 400 million hectares of land that could have been put to other uses (including returned to nature) or saved from slash-and-burn in the first place. Most dramatically, such a change would have implied a 98% reduction in agriculture workers, freeing some 1.316 billion people from toil in the fields.

This suggests that each tractor introduced in the year 2000 would have freed, on average, 150 people from a life of subsistence farming. I'd argue that much of the progress of western civilization is due to such emancipations. Just 3 million farmworkers in the US allow two orders of magnitude more Americans the freedom to specialize and increase non-farm productivity even more. Imagine how many potential Mozarts, Einsteins, and Bill Gates who have been born into a life of illiteracy and back-breaking labor among the teeming billions of subsistence farmers in the underdeveloped world. The Eco-footprint can in no way capture this cost to living 'sustainably', i.e. in poverty. 150 people per tractor sounds like a fair trade to me.

I did most of the data work in Access, but I've dumped the raw data, my (in)efficiency calculations, and American-technology projections into an Excel spreadsheet if anyone wants to have a closer look or play around with the numbers. The above analysis is almost stupidly simplistic, but at the worst it should yield some sense of the large differences between agricultural practices in different countries and the magnitude of those differences across the scales involved.


Verity said...

With regards to the second to the last paragraph, a point you do not bring up is the cost of emancipation: to the community, values, etc? What will happen to the newly unemployed workers who have no formal education if you only provided them with more efficient was to use the land? Will the industrial revolution repeat in developing nations? And what if you ended up only freeing the male workers? What greater burdens will be placed on the females who remain in the villages? In some parts of rural China, women have to take care of everything: food, children, the elderly, housing, cooking, cleaning, without the husbands/male relations as they have gone to find work in the city ('China: From the Inside' PBS 2007).

You may end up easing one 'eco-footprint' but what others do you create?

Justin Smith said...

Good point. Such a transition doesn't happen in a vacuum. In the West, the Industrial Revolution was accompanied by enhanced education and human capital for both males and females. The direction of causality depends on who you ask, but see Gregory Clark's paper “Human Capital, Fertility and the Industrial Revolution” for a chart that tracks male and female literacy in England through its Demographic and Industrial transition.

The Chinese economy needs to create 15-20 million jobs a year just to keep up. A transition to 'modern' agriculture with the same labor needs as American food production would send more than 500 million farm workers into the cities looking for work. If such a transition occurred too rapidly (maybe it already is?) the consequences for Chinese society could indeed be dramatic, challenging even the ability of the Communist Party's tanks to maintain control. This might help explain why the Chinese government is artificially devaluing its currency, reducing the return on domestic capital.

The transition wasn't always a smooth ride in the West (consider the divergent paths of the Northern and Southern US). I guess time will tell if China is able to pull it off on a larger scale over a shorter period of time.

Expanded capital in rural areas would free up female labor as well--only 5 million rather than more 500 million people would be needed to work the farms at year 2000 productivity levels. Assuming the Chinese economy can create enough non-farm jobs, people would be able to afford more capital in the home as well. In modern Western economies the prospects for women are much brighter than today's rural China. Chinese culture will probably determine how the gains and pains are distributed across genders, but geography won't be silent either.

Men are leaving the interior for the coast for jobs. The jobs are on the coast because of dramatically easier access to world markets. So, what might be done to bring the hinterland closer to world markets and make for a more evenly spatially-distributed industrialization?

Oskar said...

Justin, thanks for taking the time to put together this awesome post. It raises a number of good points. Assessing the net energy gain or loss per unit area is difficult and often the data simply aren't available. It might be worth while trying to convert things like tractors, as inputs, and agricultural production into common units, like joules. How much farmland does a tractor cost in joules of productivity when the cost of all the steel and labor and transport are combined? We would have to do this for fertilizers and pesticides as well but it would make the economic tradeoffs more apparent. My basic point in the Orientation was simply that net production requires looking at the inputs and its amazing how many reports only talk about how much is being produced.
I like that you pointed out the differences in technology across countries and the degree to which tractors might equal some number of workers. But - is it the case that one tractor would free 150 people from difficult labor or make 150 people completely unemployed? This is a difficult issue as many labor situations are highly inhumane but its still something we need to consider. Also, the degree to which labor is limiting varies from country to country. In some places, labor is very inexpensive compared to tractors and it might be hard to justify the cost of machinery from the perspective of a farmer.
And - given the costs of technology it might be the case that using so many tractors (8.8 million is a lot) would make the footprint go up.
You and Verity both rightly brought up some of the humanitarian issues that accompany eco-footprint questions and issues of the tradeoffs between environmental problems, productivity, and labor in general. A few analyses have shown that we are producing plenty of food to feed the world and pointed to unequal distribution of resources as the problem. Hopfenburg (2003) shows that current levels of food productivity could feed 3.79 times the current world population (See also Smil 2000). But getting to the point where we produce less at lower environmental cost to save machinery and land for the future while distributing in a more equitable fashion... I'm not optimistic that we'll get there soon but perhaps we should consider moves in that direction? These issues are difficult to say the least.
2000 Energy in the twentieth century: Resources, conversions, costs, uses, and consequences. ANNUAL REVIEW OF ENERGY AND THE ENVIRONMENT 25:21-51.
Hopfenberg, R.
2003 Human Carrying Capacity Is Determined by Food Availability. Population and Environment 25(2):109 - 117.

Justin Smith said...

Last month the New York Times had an interesting piece on global food trade and comparative geographic advantage that bears on some of these issues.

prince said...

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