Thomas Hager

My next book, due out in September, describes what might be the most important scientific discovery ever made -- although you’ve probably never heard of it. In 1909, two men found a method to transform air into bread (this is a bit poetic, but is actually how their work was described at the time and is a fair description of its essential effect). Their discovery, built into factories the size of small cities, is today keeping about half the people on earth alive (without it, researchers estimate, more than two billion people would starve to death).

It also carries enormous ecological implications.

The discovery, made by Fritz Haber and Carl Bosch, pulls the element nitrogen out of the air and puts it into fertilizers for growing food (and raw materials for making explosives). The problem is that the discovery has been so successful that huge Haber-Bosch plants now are pumping out rivers of nitrogen fertilizer around the world, doubling the amount of the element in our living ecosystems, creating dead zones in the oceans, polluting lakes and rivers, and deranging the delicate natural balance in forests and tundras. The nitrogen cycle in nature, like the carbon cycle, is essential for life. We are tinkering with it on a grand scale. Below is an excerpt summarizing some of the issues, from The Alchemy of Air.

Before Haber-Bosch, there were only two ways to get nitrogen out of the air and into food. One was lightning. But the most important one was the slow, steady process by which a few types of bacteria ate atmospheric nitrogen, broke it apart, and reformed it into substances plants could eat. The process is called bacterial nitrogen fixation. Some of these bacteria set up homes in nodules attached to the roots of plants, notably legumes like peas and beans, forming a symbiotic relationship in which they exchanged their fixed nitrogen for sugars and other food provided by the plants. These bacteria, working for millions of years, slowly built a stockpile of fixed nitrogen that fed most of the earth’s plants, which fed all the animals. Life on earth depended on that stock of fixed nitrogen.

Haber-Bosch turbocharged the process. Today, Haber-Bosch plants produce an amount of fixed nitrogen equivalent to that produced naturally, doubling the amount available on earth. While this massive change in natural cycles means little to the basic composition of the atmosphere -- there is so much N₂ in the air that the amount used by Haber-Bosch is negligible – it does mean a great deal to the biosphere, the places on the earth where life dwells.

Think of nitrogen atoms as riding on a series of big circles, like fairgoers on Ferris Wheels. The wheel representing the natural, pre-Haber-Bosch “nitrogen cycle” begins in the air, with N₂ molecules. The next step is to break apart the N₂, fix the nitrogen, and begin moving it through living systems, starting with either bacteria (the process of biological nitrogen fixation) or with lightning strikes ripping apart the atmospheric nitrogen and combining it with other elements. Once it is fixed and available for living things, the nitrogen is passed from molecule to molecule and organism to organism, from bacteria to plants and plants to animals, in a series of subcycles, wheels within wheels. The living organisms release the fixed nitrogen back into the dirt when they die and rot. Some of it goes back into plants and cycles again, and some of it returns to the air (different types of bacteria can reverse the process, turning fixed nitrogen back into N₂). The intricacy and interconnectedness of these cycles, the paths spreading from the air to the land to the water and back, from non-living to living systems, makes tracking difficult, research costly, and predictions almost impossible.

We know only that Haber-Bosch has altered these cycles enormously by injecting the world with a gigantic dose of synthetic nitrogen. It is as if we made the Earth itself the subject of an experiment, doubling its food to see what would happen. Scientists are just beginning to grapple with the results.

Certain effects are easier to track than others. Resesarchers estimate, for example, that about half of all Haber-Bosch fixed nitrogen ends up in our air and water, not in our food. Say that a farmer dumps a ton of synthetic fertilizer on a field. Half of it feeds the crops, some of it goes back into the air, and most of the rest dissolves in the rain or irrigation water, leaches into the ground, and ends up in streams and lakes. Again, the nitrogen is mobile, it can be incorporated into many different molecules in different ways -- but much of it enters water systems in the form of various nitrates.

The level of nitrates in the Mississippi today is four times what it was in 1900. Levels in the Rhine are double those in the Mississippi. It does not all come from farmers; there is manure runoff from ranches (the manure rich in nitrogen from animals grown on feed made by crops fed with Haber-Bosch fertilizer) and municipal wastewater with its load of excess lawn fertilizers and home sewage. While nitrogen in water is not highly toxic in the sense of poisoning people, it can rise to dangerous levels. Nitrate pollution in water has been linked to health problems like methemoglobinemia, or “blue baby” syndrome. The precise role of high nitrate levels in disease is still, however, uncertain.

What is known is that nitrogen pollution in the water ends up feeding blooms of algae and weeds that turn waterways green and cloudy. It can get so bad that it cuts off sun reaching the depths, killing life below. As the vegetation dies and rots, it pulls oxygen out of the water. As oxygen levels go down, bottom-dwelling animals, shellfish and mollusks, begin to die off. The animals that feed on them starve. Toxins begin to collect. Freshwater systems begin to die.

Then the nitrates hit the ocean. Somewhere around 1.5 million tons of fixed nitrogen flows into the Baltic Sea north of Germany every year, making it one of the most polluted marine systems on earth. Oxygen levels are so low in some areas of the Baltic that the bottom is blanketed with mats of oxygen-hating bacteria. The Baltic cod industry collapsed in the 1990s. The same thing is beginning to happen worldwide. The Great Barrier Reef in Australia is starting to show the effects of vastly increased fertilizer use, and so is the Mediterranean, and so is the Black Sea.
But the biggest and best-known of all the nitrate-affected waters in the world is the Dead Zone off the coast of Louisiana in the US, where the Mississippi and Atchafalaya rivers flow into the Gulf of Mexico. Those two river systems drain more than 40 percent of the continental US, including some of the most intensively fertilized farmland in thirty-one states. Nitrate levels in the Gulf have more than doubled in the past forty years. At the same time, life in the water has increasingly begun to suffocate. The Dead Zone is a region where aquatic plants bloom, clams and lobsters die, fish flee, and the entire ecology has changed. The Zone in the Gulf fluctuates in size with the seasons, but it is now, on average, roughly the size of New Jersey. Every year it gets a little bigger. More than 150 smaller dead zones have been identified around the world, from Chesapeake Bay to the coast of Japan. Nitrogen pollution is not the only cause – water currents, temperatures, and natural fluxes in the growth of plants and animals also play a part – but Haber-Bosch plays a major role. Here again, much remains to be learned.

Just as poorly understood are the effects of Haber-Bosch nitrogen in the air. Some of it ends up in the air not as innocuous N2, but as nitrogen-containing pollutants, including the notoriously dirty nitrogen oxides. Most of the oxides polluting our air come from burning fossil fuels in car engines and factories. But a portion, somewhere between 15 and 50 percent depending on how you count it and how far down the food chain you go, come directly or indirectly from Haber-Bosch plants. Spread fertilizer on a field, and a portion of it goes directly into the air, much of it from bacteria that break down the fixed nitrogen and release it as gases. This is especially true in flooded fields, like rice paddies. Again, some of the gas is innocuous N₂, the same atmospheric gas that started the process, a completion of a cycle. But part of it is released into the air as nitrous oxide, for instance, a potent greenhouse gas. Again, we have much to learn. No one knows exactly how much fixed nitrogen from Haber-Bosch products ends up in the air, or how much ends up in exactly what molecular forms. All we know is that it is a lot.

Of course, the pollutants don’t just stay there. They fall or get washed back to earth in the rain, and when they do fall, they become fertilizers. What Haber-Bosch has done (along with the nitrogen oxides released by burning oil and coal) is to turn our atmosphere into a huge fertilizer silo. We are the beneficiaries of a bounty that the ancients could only dream about: tons of growth-promoting fertilizers showering from the sky. The amount of fixed nitrogen filtering down to earth in some places has risen so high that it equals the amount American farmers typically apply to their spring wheat. Again, the long-term effects of this worldwide change are uncertain. At first blush, it might seem like a great thing, the air enriched, a simple way to green the earth.

But the news is not all good. Nitrogen oxides (along with sulfur compounds in the air) create acid rain. That problem has received a lot of attention. Less attention has been paid to the issue of air-borne fertilizer altering the amount of fixed nitrogen available to every ecosystem on the globe, from tundra to jungle, forest to prairie, ocean to desert. Some early studies indicate that ecosystems fed with the extra nitrogen begin, as expected, by flourishing. Then they reach a sort of saturation point in which at least some forests move into a “destabilization phase” in which productivity falls. If that happens, the system is less able to consume nitrogen, and more of what falls goes into the water. Soil chemistry changes. Species distributions change as nitrogen-hungry varieties outmuscle those naturally adapted to lower nitrogen levels. Natural systems are thrown awry.
Finally, questions remain about how the flood of Haber-Bosch nitrogen is affecting human agriculture and global populations. The easy availability of synthetic fertilizer has resulted in an increase in massive-scale monoculture farming, with the additional corn and other grains making possible huge animal factories.

Haber-Bosch is not the only reason for our current agricultural system – increasing mechanization and advances in plant genetics are important as well – but it plays a critical role. Most humans have moved past the old traditional methods of crop rotation and manuring, severed the old ties between crops and domestic animals, increased average farm sizes and decreased crop varieties. These developments offer terrific benefits, feeding many more people much better than our ancestors thought possible – but also carry clear risks for soil quality, plant disease, and decreased diversity.

I live in a college town. Like many college towns, mine is both enviably liveable and decidedly liberal. But even here, among a highly educated populace, I find that most people I talk with (outside of the university's scientists) have a hole in their understanding of modern culture: They know next to nothing about science. They do not know where or when it started. They do not know how it is done. They do not know who sets its priorities, or how it is paid for, or the full impact it has on our society.

In place of understanding, many people adopt fantasies about science. Call it the "Dr. Frankenstein" default: Scientists wield great power without great care. Scientists act more like computers than people. Scientists create monsters.

I know enough about the history of science to know that the lives of scientists and the effects science has on our world are much more nuanced, complex, interesting -- and far more important, often in unexpected ways -- than most people realize.

Science is an art, a craft, a business, a tool, an obsession, a route to fame and riches, a form of creativity, an expression of power. In short, it is a very human activity. And like any human activity -- business, art, leisure, religion, political activism, whatever -- it draws both good and bad people, and offers both great benefits and enormous dangers. The trick is to understand enough about it to use it wisely.