World Population: How Did It Get So Big?
1. The Haber-Bosch Process
As I have been writing this article, the world population has passed 6.8 billion. Today it's 11% more than what it was (6.1 billion) when the 20th Century ended - and when MIT Press published a book called Enriching the Earth: Fritz Haber, Carl Bosch, and the Transformation of World Food Production.
The book is about the process of synthesizing ammonia. Fritz Haber, a German, invented the process in 1909 and was awarded the Nobel Prize in Chemistry in 1918. Carl Bosch, another German working for the chemical company BASF, shared the Nobel Prize in 1931 for industrializing the process that Haber invented.
According to MIT Press, the Haber-Bosch process "has been of greater fundamental importance to the modern world than ... the airplane, nuclear energy, space flight, or television. The expansion of the world's population from 1.6 billion people in 1900 to today's six billion [in 2000] would not have been possible without the [industrial] synthesis of ammonia."
The synthetic ammonia produced by Haber-Bosch is a chemical compound of the elements hydrogen and nitrogen, and for our purposes the important element is nitrogen. Although nitrogen is abundant in the atmosphere as a gas, it is unusable until it has been fixed - converted into a form such as ammonia that is usable. Fixed nitrogen is of particular importance for fertilizers and munitions. But naturally fixed nitrogen is scarce. Germany used the Haber-Bosch process in World War I (1914-1918) to make synthetic nitrogen for explosives. Some believe that without Haber-Bosch, Germany would have run out of explosives in 1916 and might have had to quit the war two years before it actually did.
But we're interested in the connection between Haber-Bosch and human procreation, not human destruction. We're interested in synthetic nitrogen fertilizer.
3. Haber-Bosch and Population Growth
But by 1900, arable land around the world was pretty much maxed out, and the rhizobia working the land, bless them all, could fix only some 140 million metric tons of nitrogen a year. Thunderstorms rained down another 10 million tons of nitrogen fixed by lightning. But that was it. One hundred fifty million metric tons per year. Bacteria and lightning are nature's only nitrogen fixers. Farmers, of course, recycled what they already had as manure and compost. And nitrogen was also being extracted from nitrate mines in Chile (fossil nitrogen) and collected as guano from sea bird excrement. But by the early 1900s human population growth had its nose pressed up against the window of maximum food production.Then Fritz Haber and Carl Bosch broke the window.
Haber-Bosch worked around the limits of natural nitrogen production by manufacturing synthetic nitrogen fertilizer. Today, according to International Fertiliser Industry Association statistics, some 100 million metric tons of nitrogen produced by Haber-Bosch are applied annually to crops around the world, more than half of it to cereal crops. (See chart below.)
The increase in food production that Haber-Bosch facilitated has led to a very substantial increase in the world population. Almost all of the recent increase has occurred in less developed countries where, for many people, Haber-Bosch has meant the difference between starvation and survival. The author of Enriching the World, Professor Vaclav Smil of the University of Manitoba, estimates that "only about half of the population of the late 1990s could be fed at the generally inadequate per capita level of 1900 diets without nitrogen fertilizer." That's only three million people - what the population was in 1960. In other words, but for Haber-Busch, no more than half of today's population would be alive!
2. The Nitrogen Factor in Population Growth
Nitrogen is an essential part of amino acids and nucleic acids, and therefore of proteins and genes, in the cells of all living organisms, whether animal or vegetable. Nothing can live without it. But the nitrogen has to be fixed. Unfixed nitrogen can't be assimilated by most organisms including people. So how, we may ask, did people obtain the nitrogen required to sustain life before 1909 when Haber-Bosch was invented?
People obtain nitrogen the same way they obtain almost all their nutrients - by eating green plants or animals that eat green plants. Green plants have the unique ability to create nutrients from simple chemicals in their environment using energy that they've stored away as glucose (sugar). The glucose, in turn, is created from carbon dioxide in the air and water in the ground using sunlight as energy in a process called photosynthesis. This process of converting solar energy into biochemical energy also creates oxygen, which the plants don't need but we do - to breathe.
Green plants not only require nitrogen for their cells, as we do, but also for chlorophyll, the green pigment that absorbs the sunlight that provides the energy for photosynthesis. Then how, we ask again, did the plants get the nitrogen that they pass on to us when we eat them before Haber-Bosch was invented?
Back at the dawn of civilization, when hunter-gatherers were becoming farmers, they discovered that their main food crop - a cereal like wheat or rice or corn - depleted the fertility of their soil unless they alternated these crops with legumes such as peas, lentils, soy, alfalfa or clover. Legumes, it turns out, provide a home in their roots for soil bacterial called rhizobia that fix nitrogen on their own - one of the few organisms that can do so. The fixed nitrogen, converted by other bacteria into nitrates, fertilizes the soil and the green plants including cereals and legumes that grow on the soil.
To recap, every living organism on Earth needs nitrogen. We get ours directly or indirectly (through animals) from green plants. Green plants get theirs from the soil. And the soil gets its nitrogen from nitrates created by bacteria.
(continued in column to right →)
4. The Green Revolution and Population Growth
Quite a story, don't you think?
Except that it turns out to be only half the story.
During the period between the two world wars, when Haber-Bosch processing plants had been converted from munitions to fertilizer and new processing plants were being built, the application of synthetic nitrogen fertilizer was limited because the crops in use during this period didn't respond as expected to the added nutrients and therefore crop yields didn't significantly increase. Professor D. Gale Johnson of the University of Chicago points out in his review of Enriching the Earth that "yields of corn and wheat in the United States were essentially the same in the late 1920s as in the late 1860s or even in 1800" and that wheat yields in England in 1918-45 were less than 10% higher than in 1832-59.
What Haber-Bosch needed was new high-yield varieties (HYVs) of crops bred to have an enhanced capacity for absorbing nitrogen.
The first HYV cereal crop was corn (maize) that was commercially developed in the U.S. in the 1930s. The improved yields from applying nitrogen fertilizer to the new corn started showing up in U.S. Department of Agriculture statistics towards the end of that decade (see arrow in chart above).
In 1943, at the urging of U.S. Vice President Henry Wallace, who was raised on an Iowa farm and knew something about agriculture, the Rockefeller Foundation set up an agricultural research station in Mexico in collaboration with the Mexican Government. The fruit of that collaboration was HYV wheat, and Mexico became a net exporter of it.
In the early 1960s the Rockefeller Foundation and Ford Foundation set up a research organization in the Philippines in cooperation with the Philippine Government. The fruit of that collaboration was HYV rice.
India began using the new wheat and rice varieties in the 1960s. The increase in food production was so spectacular, not only in that country but also in other Asian countries and in Latin America, that William Gaud, head of the U.S. Agency for International Development, coined the term Green Revolution to describe it. I worked for the agency in those days when its large Indian program was focused on developing fertilizer plants, irrigation projects and other accoutrements of the new HYV farming techniques in the hope that they would eventually replace the large wheat imports which the agency financed. One day in the 1970s, after leaving the agency, I read in The New York Times that India had become a net exporter of wheat. The efforts had not been in vain.
In 1970, Dr. Norman Borlaug, who like Henry Wallace was raised on an Iowa farm and who had a lot to do with developing the high-yielding wheat variety in Mexico and introducing it into India, was awarded the Nobel Peace Prize.
The Green Revolution is not without its issues. Many of them relate to the Haber-Bosch factor, particularly the use of nonrenewable and environmentally degrading sources of energy in manufacturing nitrogen fertilizer and the release of nitrogen that is not taken up by the crops into the environment.
The National Organics Program supervised by the U.S. Department of Agriculture will not certify any agricultural product as organic if it is grown with synthetic nitrogen fertilizer.
From a broader perspective, the problem with the Green Revolution, as with the Industrial Revolution in general, is that we've left out the maintenance. We've sold the many benefits of the revolution to ourselves and our families but haven't yet provided for the costs of repairing the infrastructure and developing renewable sources of energy so that these benefits will be available to our new or as yet unborn grandchildren.
Meanwhile, the world population continues to grow at a much faster rate than it ever grew before Haber-Bosch and the Green Revolution.
I look forward to your comments.
riversedge (aka Mord)
More by this Author
Fossil fuel market prices don’t reflect the externality, or social cost, of pollutants, including carbon dioxide that causes global warming. Since the catastrophic effects of climate change will occur decades in...
Changes in Earth's temperature used to be caused by changes in sunlight, which in turn were caused by irregularities in the Earth's orbit around the Sun. Now, however, temperature changes are caused by changes in...