What are the environmental consequences of growing the food supply to feed the world in 2050?

The most recent UN estimates show global population stabilizing at 9-10B sometime after 2050. What will it take to feed these additional 2-3B people?

While forecasting anything 40 years in the future is a treacherous task, estimates typically place the required expansion of the food at double current production levels in 2050.1 I often find it easier to visualize some of these data to get a better sense of the magnitude:

Data from UN sources. FAO statistics database http://faostat.fao.org/site/609/DesktopDefault.aspx?PageID=609#ancor and population database http://esa.un.org/unpd/wpp/index.htm

It is interesting to note that during the past 50 years, otherwise known as the green revolution, global food supply has grown faster than global population. Thomas Malthus must be quite happy that his 1798 prediction that the food supply was limited to linear growth has proven incorrect, at least thus far. Malthus failed to predict that increases in yield per cultivated area would increase simultaneously with total area under cultivation. In other words, increases in the food supply are driven by:

The first term, yield per cultivated area, has driven a majority of the expansion of the global food supply in the past 50 years. Future improvements will also likely lean on this lever.

Understanding of the potential environmental impacts of expanded food production  requires bit deeper dive into the factors that will drive the increase. Luckily others have already completed great work on this topic. Tilman et. al. lay out the drivers of the future impact in their 2000 paper Forecasting Agriculturally Driven Global Environmental Change.

Yield per cultivated area is a function of:

  • Fertilizer application
  • Irrigation
  • Pesticide application
  • Yield potential of crops2

Cultivated area is a straightforward function of area under crop or pasture production.

The use of these inputs for food production in their current form also have negative environmental impacts. These impacts include:

  • Irrigation drives salt and nutrient loading to downstream aquatic ecosystems, salinization of soils, and pressure on limited water availability
  • Fertilizers drive eutrophication3 of estuaries and coastal seas, loss of biodiversity, groundwater pollution, increases in smog and ozone depletion and acidification of soils
  • Pesticide drives general environmental degradation and human health effects
  • Conversion to cropland drives global habitat destruction and loss of native ecosystems

Tilman et. al. conclude that given the current trajectory of food production, the environmental impact in 2050 will be quite large.

  • Irrigation – 2.0 fold increase in area under irrigation, placing severe stress on global water tables
  • Fertilizers – 2.4 to 2.7 fold increase in nitrogen- and phosphorus-driven eutrophication of terrestrial, freshwater, and near-shore marine ecosystems
  • Pesticide – 2 to 3 fold increase in pesticide use, leading to general environmental degradation & human health concerns
  • Cropland conversion – 1 billion hectares of natural ecosystems converted to agriculture by 2050 (about the area of the U.S.)

There is clearly a need to find solutions to ensure adequate food supply growth while simultaneously using less fertilizer, water, pesticide and land per unit of output. This is a massive but important challenge, and one which will provide ample opportunity for entrepreneurial innovation over the coming 40 years.

As a quick end note, it is interesting to examine the predictions of Tilman et. al. 10 years in to their 50 year predictions (the report was published in 2000). Using the same UN statistics, the annual use of key inputs can be examined and compared to the estimates of the study. In the figures below (please click on the images for a larger version), note that irrigated land and both types of fertilizer are closely tracking the predictions. Both cropland and pasture land, however, are falling well below predictions. I will not speculate here to the causes of this phenomenon, but it does give hope that we’ve already made progress to grow the food supply with fewer inputs.

Irrigated landNitrogenous fertilizerPhosphate fertilizer

 

Crop landPasture land

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  1. These estimates assume an increasing shift to more protein-dense, calorie-rich Western style diets. For example, this UN report on Global Agriculture Towards 2050 reports an expected availability of 3,050 calories per capita per day. [return to reading ↩]
  2. Yield potential is the theoretical yield under ideal conditions. See this definition for more information [return to reading ↩]
  3. I thought it was a made up word as well. See Wikipedia for more information [return to reading ↩]
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One Response to “What are the environmental consequences of growing the food supply to feed the world in 2050?”


  • Comment from Jorge

    Ben, Nice article, rich in data and links.

    In addition to pressures due to increasing population, bio-fuels will also be increasing the demand for agricultural outputs and acres. This will add to the pressure over the environment.

    Jorge
    http://www.bluerivert.com


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