Without Haber-Bosch, Half the World Starves

A grain of wheat is roughly 2% nitrogen by weight. That sounds like a footnote, until you ask where the nitrogen came from. It did not fall from the sky in a useful form. It was not mined from the ground like iron or copper. Somewhere between the atmosphere and your plate, something had to break one of the strongest chemical bonds in nature and rearrange it into a molecule that plants can absorb. That something is a process most people have never heard of, and it feeds roughly half the humans alive today.

The Problem in the Air

Earth's atmosphere is 78% nitrogen. The gas surrounds every field, every forest, every ocean. And yet plants cannot use it. Atmospheric nitrogen exists as N₂, two atoms locked together by a triple bond that requires 945 kilojoules per mole to break. For context, that is among the strongest bonds in all of chemistry.

Think of it as being adrift at sea. Water everywhere, none of it drinkable. Nitrogen everywhere, none of it accessible to the roots pulling nutrients from the soil.

Before the twentieth century, agriculture had exactly three sources of usable nitrogen. Farmers spread animal manure and composted human waste. They rotated crops with legumes, whose root bacteria can fix small amounts of atmospheric nitrogen into the soil. And where money allowed, they imported guano from Pacific islands or sodium nitrate from Chilean deserts. These sources set a ceiling. Around 1900, with a global population of roughly 1.6 billion, the world was already approaching it.

Breaking the Bond

Fritz Haber, a German chemist, cracked the problem in 1909. In his laboratory at the University of Karlsruhe, he demonstrated that nitrogen from the air could be combined with hydrogen to produce ammonia: N₂ + 3H₂ yields 2NH₃. The trick was brute force. The reaction required temperatures between 400 and 500 degrees Celsius, pressures of 150 to 300 atmospheres, and an iron-based catalyst to coax the stubborn nitrogen molecules into reacting at all.

Making it work in a flask was one thing. Making it work at industrial scale was another. Carl Bosch, an engineer at BASF, solved that second problem. He developed high-pressure steel reactors that could withstand the extreme conditions without corroding or exploding. By 1913, the first industrial ammonia plant was running at Oppau in the Rhineland.

The achievement earned both men Nobel Prizes, Haber in 1918 and Bosch in 1931. It also began a transformation in food production that is still accelerating.

The Dark Side of the Inventor

Haber's biography does not end at the Nobel. During World War I, he turned his chemical expertise toward weapons. He personally directed the first large-scale chlorine gas attack at Ypres on April 22, 1915, supervising the release of 168 tonnes of chlorine from nearly 6,000 cylinders. The gas killed an estimated 1,000 soldiers and injured thousands more.

His wife, Clara Immerwahr, also a chemist and one of the first women to earn a doctorate in chemistry in Germany, opposed his weapons work. On May 2, 1915, ten days after the Ypres attack, she took his military pistol and shot herself in the garden of their home. Haber left for the Eastern Front the next morning.

After the war, Haber's institute developed Zyklon A, a cyanide-based pesticide. A modified version, Zyklon B, was later used in the gas chambers of the Holocaust. Haber himself, of Jewish origin, was forced to resign his positions when the Nazis came to power in 1933. He died in exile in Basel in January 1934, before the full horror of what his institute's work had enabled.

The man who figured out how to feed the world also figured out how to gas it. There is no tidy moral in that duality, only the reminder that a chemical process carries no ethics of its own.

Why It Needs Natural Gas

Here is the part that connects a century-old invention to a war in the Persian Gulf.

Look at the equation again: N₂ + 3H₂ yields 2NH₃. The nitrogen comes from air, which is free and everywhere. But where does the hydrogen come from?

In practice, it comes from natural gas. Through a process called steam methane reforming, methane reacts with steam at high temperatures: CH₄ plus H₂O yields CO plus 3H₂. Natural gas provides the hydrogen atoms that combine with nitrogen to form ammonia. It also provides the energy to heat the reactors. Two dependencies packed into one feedstock.

The numbers are concrete. Producing one tonne of ammonia requires approximately 33 gigajoules of natural gas. Globally, ammonia plants churn out roughly 190 million tonnes per year. That production alone consumes between 1 and 2 percent of all global energy. Not electricity. Not transportation fuel. Chemical feedstock for growing food.

When a conflict disrupts natural gas supplies from the Persian Gulf, it does not merely raise heating bills or electricity prices. It reaches directly into the supply chain that manufactures the molecule plants need to grow.

Four Billion Mouths

How dependent is the world on this single process? Vaclav Smil, the Czech-Canadian scientist who has spent decades quantifying energy and food systems, put it bluntly: without synthetic nitrogen fertilizer, the earth could support roughly 3 to 3.5 billion people at current dietary standards. We have passed 8 billion. The arithmetic is stark.

The growth curve tells the story. In 1960, the world used roughly 10 million tonnes of synthetic nitrogen per year. Today that figure exceeds 110 million tonnes. Over the same period, global crop yields per hectare roughly doubled. The two curves are not coincidental. Nitrogen is the nutrient most often limiting plant growth, and synthetic fertilizer removed that limit across billions of hectares simultaneously.

Some numbers sharpen the picture further. China alone consumes about 30% of global nitrogen fertilizer. India accounts for nearly a fifth. These two countries feed over a third of humanity, and both depend overwhelmingly on the Haber-Bosch process to do it. If you removed synthetic nitrogen from world agriculture tomorrow, yields would fall by 40 to 50 percent. Not in a decade. In the first growing season.

Why There Is No Quick Replacement

If the process depends on natural gas, why not switch to another hydrogen source? The question is fair. The answer is engineering reality.

Green hydrogen, produced by splitting water with renewable electricity, can in principle replace methane-derived hydrogen in ammonia synthesis. Several pilot plants exist. But producing hydrogen through electrolysis requires enormous amounts of electricity, and building electrolyzers at the scale needed to replace even a fraction of current ammonia production would take decades and trillions of dollars in investment. As of 2025, green ammonia accounts for less than 1% of global production.

Other paths are even further out. Electrochemical ammonia synthesis, which would produce NH₃ directly from air and water using electricity, remains at the laboratory stage with yields far too low for any commercial application. Enhanced biological nitrogen fixation, engineering bacteria to fix nitrogen more efficiently or extending the ability to non-legume crops, is promising science but decades from field deployment at meaningful scale.

The installed base of conventional ammonia plants represents over a century of engineering refinement. These facilities have operational lifespans of 30 to 40 years and represent hundreds of billions of dollars in capital. Even under optimistic scenarios, green ammonia might account for a few percent of global production by the mid-2030s. The vast majority will still run on natural gas.

The Invisible Dependency

Every supply chain has a link that most people never see. In the chain that runs from a Persian Gulf gas field to the food on a table in Cairo or Delhi or São Paulo, the Haber-Bosch process is that link. It sits between the hydrocarbon and the harvest, converting fossil energy into the nitrogen that builds every protein in every plant that feeds every human on earth.

When policymakers discuss energy security, they typically mean electricity and transport fuel. When they discuss food security, they typically mean harvests and trade routes. The Haber-Bosch process sits in the gap between these two conversations, connecting them in a way that most analysis overlooks.

Understanding this chain does not change the chemistry or speed up the alternatives. But it does change what you see when you read about gas prices, shipping disruptions, and the Strait of Hormuz. The crisis is not just about energy. It is, at its molecular foundation, about food.