The Contribution of Fossil Fuels to (a) Feeding Humanity and (b) Habitat Conservation?

Guest post by Indur M. Goklany

Analyses of policies related to fossil fuel usage usually focus on the negative impacts from that usage, while generally ignoring the positive aspects, such as their contribution to global food production and, through that, the alleviation of hunger which, it should be noted, is the first step to maintaining a healthy and productive population. Fossil fuels, however, are critical for food production worldwide. They contribute to food production via a number of pathways:

• They serve as raw materials for the production of fertilizers and pesticides, without which yields would be substantially lower.

• They provide most of the energy needed to move agricultural inputs (including water) and agricultural outputs to and from farms, markets and consumers.

• Fossil fuels also provide the energy for running farm machinery.

• They have helped increase atmospheric carbon dioxide concentration, which increases the rate of photosynthesis and water use efficiency in crops (and other vegetation).

• Much of the decrease in post-harvest losses, from farm to eventual consumption, also depends on fossil fuel powered technologies (e.g., refrigeration, storage in plastic products, and more rapid delivery systems).

Here I will develop a lower bound estimate of the contribution of fossil fuels to global food production. Specifically, I will address nitrogen fertilizers and pesticides, that is, only the first of the five pathways identified above by which fossil fuels enhance food supplies. Consequently, considering only this pathway would understate the contribution of fossil fuels to global food production.

Also since fossil fuels help increase agricultural yields, that limits the amount of habitat converted to cropland. Notably, such conversion is generally regarded to be the greatest threat to ecosystems and biodiversity worldwide (Wilcove et al., 1998; Millennium Ecosystem Assessment, 2005). Therefore higher yields imply higher habitat conservation (Goklany 1998). Here, I will also provide a lower bound estimate the amount of land that has been “saved” from being converted to cropland.

Contribution of Nitrogen Fertilizers to Global Food Production:

Nitrogen, the fourth most abundant element in the human body, is critical for life on earth. It is an essential component of amino acids, proteins, RNA and DNA. Without it, plants would not grow and there would be no food.

It is also the most abundant gas in the atmosphere. However, plants are generally unable to directly use the nitrogen in the air for their growth. For that, nitrogen has to be “fixed” in the soil (or other growth medium) via either natural processes (e.g., through the action of various soil or aquatic bacteria) or synthetic processes. Generally, natural processes are unable to fix nitrogen in the amounts needed to feed humanity. This is why synthetic processes have to be used to fix nitrogen in the form of fertilizers which can then be used to grow crops.

Synthetic fixation of nitrogen is accomplished via the Haber-Bosch process. [Vaclav Smil, writing in Nature, called the Haber-Bosch process the most important invention of the twentieth century (firewalled). I agree. Fritz Haber and Carl Bosch—both Nobel Prizewinners before the Nobel Prize was devalued by the political shenanigans of the Norwegian committee awarding the Nobel Peace Prize—received Nobel Prizes in Chemistry (I believe) in 1918 and 1931, respectively.]

In this process, invented in 1908, hydrogen is first produced from natural gas, and then reacted with nitrogen from the air under very high temperature and pressure in the presence of a catalyst (generally iron). Because the hydrogen is derived from natural gas, and the need for high temperatures and pressures, the entire process is very energy-intensive. According to one estimate, 1% of world’s energy is used for this process.]

Erisman et al. (2008) estimate that in the 100 years since the invention of the Haber-Bosch process, that even as the global population has increased, the percentage of global food production dependent on nitrogen from the Haber-Bosch process has grown. By 2008, they estimate, it was responsible for 48 percent of global food production (see Figure 1). Thus, as they note, “the lives of around half of humanity are made possible by Haber–Bosch nitrogen.” Their estimate, which is generally consistent with earlier estimates (e.g., Smil 1999, Stewart et al. 2005), assumes that in the absence of the Haber-Bosch process, other substitute technologies would have boosted productivity by 20% between 1950 and 2000.

Figure : The percentage of the world’s population estimated to be fed through the Haber-Bosch process, 1908 to 2008 (indicated by the short dashed line, right axis). Trends in human population and nitrogen use throughout the twentieth century are also shown. The total world population is shown by the solid gray line (left axis). The estimate of the number of people that could be sustained without nitrogen from the Haber–Bosch process is shown by the long brown dashed line. The average fertilizer use per hectare of agricultural land (blue symbols) and per capita meat production (green symbols) is also shown. Source: Erisman et al. (2008).

Figure 1 shows that in the absence of the Haber-Bosch process, the world would have had enough food to feed only 3.5 billion people (out of a world population of 6.7 billion) in 2008. It would be even fewer if there were no fossil fuels.

This is because regardless of which substitute technologies are used they would more likely than not rely on energy to one degree or another: No substance can be extracted, moved, processed and distributed without an investment of energy. And in today’s world, energy is synonymous with fossil fuels for practical purposes. Currently, 81% of the world’s energy consumption is derived from fossil fuels (and 6% from nuclear). Consequently, the 48% estimate derived by Erisman et al. (2008) as the contribution of the Haber-Bosch process to world food production is a lower-bound estimate.

Contribution of Pesticides to Global Food Production

Oerke (2006), used data from 19 regions around the world for 2001–03 to estimate losses in five major food crops from the full gamut of pests: pathogens (fungi, chromista, bacteria), viruses, animal pests, and weeds. He estimates that in the absence of pesticides, 50–77 percent of the world’s wheat, rice, corn, potatoes and soybean crop would be lost to pests. Fortunately, pesticides have reduced these losses to 26–40 percent. But most pesticides are made from feedstock derived from petroleum, another fossil fuel.

If one assumes that the mid-point of the above ranges for actual and potential losses due to pests applies to global food production, then in the absence of any pesticides, yields would be 46% lower. However, one ought to expect that in the absence of fossil fuels, substitute pest control methods would be employed. In the following, I will assume that in the absence of fossil fuels, actual yields would be 10% lower, although that might be an overestimat

e. But it will serve the purpose of developing a lower-bound estimate of the contribution of fossil fuels to food production.

A Lower-Bound Estimate of the Contribution of Fossil Fuels to Global Food Production

Combining the lower bound estimates of the contribution of fossil fuels to food production via nitrogenous fertilizer and pesticides indicates that because of fossil fuels, food production increased by at least 114% in 2008. That is, in their absence, food production would have been at least 53% lower.

A Lower-Bound Estimate of the Contribution of Fossil Fuels to Habitat Conservation

The corollary to the above estimate is that, in the absence of fossil fuels, the world would have needed at least 114% more cropland in 2008 to produce the same amount of food as it actually produced with the help of fossil fuels. But, as noted, conversion of habitat to cropland is probably the primary threat to ecosystems and biodiversity worldwide.

The above estimate assumes that the new cropland is just as productive on average as current cropland. But this is doubtful, since the best cropland is likely to already be in use currently. This reinforces the fact that the 114% is a lower bound estimate.

Since today there are 1.53 billion hectares of cropland worldwide (FAOSTAT), we would need an additional 1.75 billion hectares to meet the present level of food demand. To put this number in context, in 2006, the World Resources Institute estimates that there were a total of 1.41 billion hectares set aside for full or partial protection of biodiversity. This includes areas set aside for strict protection to areas set aside for sustainable use of resources.

So it seems fossil fuels have preserved more land from being converted to human use than all the other preservation effort undertaken to date (despite Prince Charles and Richard Attenborough’s best efforts).

Summary

Just the contribution of fossil fuels to global food production would outweigh whatever damage that has been attributed to fossil fuels, whether it is from real pollutants (e.g., particulate matter, sulfur dioxide, etc.) or from hypothesized bogey-molecules such as carbon dioxide. That they have, moreover, also “saved” more habitat from conversion to agriculture is a bonus beyond compare.

So the war with fossil fuels would seem to be counterproductive.

References:

Erisman, J.W., Sutton, M.A., Galloway, J., Klimont, Z, and Winiwarte, W. 2008. How a century of ammonia synthesis changed the world. Nature Geoscience 1: 636–639.

FAOSTAT.

Fogel, R.W. 1995. The Contribution of Improved Nutrition to the Decline of Mortality Rates in Europe and America. In: Simon, J.L. Ed. The State of Humanity. Cambridge, MA, Blackwell, 61–71.

Goklany, I.M. 1998. Saving Habitat and Conserving Biodiversity on a Crowded Planet. BioScience 48: 941-953.

Millennium Ecosystem Assessment [MEA]. 2005. Synthesis Report. Washington, DC, Island Press.

Oerke, E.-C. 2006. Centenary Review: Crop Losses to Pests. Journal of Agricultural Science 144: 31–43.

Smil, V. 1999. Detonator of the population explosion. Nature 400: 415.

Stewart, W.M., Dibb, D.W., Johnston, A.E., and Smyth, T.J. 2005. The Contribution of Commercial Fertilizer Nutrients to Food Production. Agronomy Journal 97: 1–6.

Wilcove, D.S., Rothstein, D., Dubow, J., Phillips, A. and Losos, E. 1998. Quantifying threats to imperiled species in the United States. BioScience 48: 607–615.