The Farmland Required to Feed Humanity Has Peaked

By William Tucker

Usually the environmental news is bad. We're running out of fossil fuels or room to put their exhausts or water or space to put our garbage or what have you.

This time, however, the news from the Rockefeller University's Program for the Human Environment is good. Due to improved yields, slowing population growth, growing affluence and changing consumer habits, the world appears to have hit "peak farmland," meaning that the land required to feed humanity has hit a maximum. The result is that much land now used for agricultural may eventually be returned to its natural state.

The only wild card in the deck is biofuels, which accounts for almost all the additional land put under cultivation over the last two decades. The authors of the study - Jesse Ausubel (Ausubel), Iddo Wernick and Paul Waggoner - are not enthusiastic about biofuels and believe that if supporters take a second look, they may tone down their support. Then the world would be on a downward slope in the agricultural consumption of land.

The report, entitled "Peak Farmland and the Prospect of Land Sparing," appears in the current issue of Population and Development Review. It chronicles the extraordinary progress made by India and China in the last several decades in feeding their populations while at the same time actually returning some land to forestation.

"[Since 1960,] India's population rose over two and a half times, while national income rose 15 times. By 2010 the average Indian ate a sixth more calories than in 1960."  Nonetheless, "[t]he 5MHa [million hectares] added to forests from the 1960s to 2000 exceeds the size of the state of Iowa in the US. The reversal of deforestation hints at an associated peak in farmed land."

So too, in China, "[w]hile the area of harvested Chinese corn doubled during the half- century, each harvested hectare became more than four and a half times more productive. The 120MHa of land spared is the equivalent of 2 Frances or 8 Iowas."  As a result, "the extent of Chinese forests reportedly expanded 30 percent from 1990 to 2010."

Their conclusion - which runs against the grain of much environmental thought - is that the Green Revolution and its introduction of advanced agricultural techniques into the developing world was a success. "Unlike some other revolutions of that era, this one has proven enduring and provides the continuing benefit of reducing cropland expansion to feed ever more mouths."

Ausubel, Wernick and Waggoner separate out five qualities they say account for the impact of agricultural activity on the available land. They are:

1) Population

2) Affluence, as measured in GDP per capita

3) Consumption 1, which tracks how people change their diet in response to affluence

4) Consumption 2, which tracks the proportion of land used for non-food crops

5) Technological improvements, measured by the amount of land farmers use versus the value of their crop.

The authors find that while the rate of world population growth started falling in 1970, the biggest impact has come from technological improvements, plus people's response to growing affluence. Surprisingly, the demand for food turns out to be fairly inelastic. Above a certain level of affluence, people do not increase their caloric intake. Ausubel, Wernick and Waggoner call this "dematerialization" and say it plays a significant role in reducing the demand for farmland. Also encouraging is that China and particularly India are NOT increasing their meat consumption to the same level as Western nations.

"As the Chinese grew more affluent after about 1970, their meat consumption grew rapidly with little dematerialization. By the 1990s, however, the FAO reported Chinese meat consumption rising less than half as fast as affluence and dematerializing 6 percent per year from 1995 to 2007. As Indian consumers grew more affluent, they behaved differently. They scarcely increased their meat consumption during the half-century to 2010, causing rapid dematerialization and even exhibiting income elasticities below zero. Globally, average meat consumption dematerialized little from 1980 to 1995, but then as in China, it rose only half as fast as affluence from 1995 to 2007."

The result is that "the battle to feed humanity" does not appear destined to outrun the world's land resources. Granted, much of this has been achieved through the application of fossil fuel resources to agriculture, both through intensive use of fertilizers and the mechanization of processes. But even here the inputs seem to be leveling off to a sustainable level.

During the first years of the Green Revolution, for instance, consumption of nitrogen fertilizers sometimes outraced crop production by as much as 10 percent. But this trend slowed to between 0.5 and 2.5 percent in the 1980s so that over the last 40 years fertilizer use per unit has risen at an annual rate of only 0.72 percent. Instead, most improvements in crop production now come through a cluster of advances known as "precision agriculture."

Water consumption has also leveled off. In the United States, the withdrawal of water for irrigation actually peaked in 1980 and has since declined relative to crop production at an average rate of 2.0 percent per year. All those small improvements in drip irrigation and drought-resistant varieties eventually add up.

The only surprise has been a reversal of an improving trend in the C2 factor, which measures agricultural output per calory in the food supply. With the decline in demand for cotton and tobacco, this tend had been improving. But a reversal has come with the growth of crops-for-fuel. Ironically, in trying to stretch oil resources, environmentalists have ended up stressing an even more important resource, fertile land. The authors write:

"As the shortcomings of biofuels become evident to governments and champions of the environment alike, we conservatively project C2 as slowing to 0.4 percent annually, slightly less than half the 1995-2010 level. . . . A biofuels bust would lead to a negative value."

The overall result is that, even if the dubious effort to turn corn into ethanol continues to consume almost half the American corn crop, world trends are moving in the right direction. As Ausubel, Wernick and Waggoner conclude:

"Another 50 years from now, the Green Revolution may be recalled not only for the global diffusion of high-yield cultivation practices for many crops, but as the herald of peak farmland and the restoration of vast acreage to Nature."

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