We share interesting science words and ideas in our regular "Word Encounters" series. Here, Staff Writer Stewart Mittnacht discusses the word "Anthropocene," referring to the geological period in which human activity has been the dominant influence on the climate and the environment. Scientists debate the starting date for this epoch. Tell us what you think!

Chances are you’ve come across the term “Anthropocene” in the media, from mentions on the radio to articles in the likes of The New Yorker to Nature to National Geographic.

The Anthropocene is a proposed geologic epoch to describe the period in which human activity began to significantly impact the Earth’s ecosystems. Meaning “new human age,” the term reflects a growing consensus that our technology and actions have permanently altered the Earth’s geology. Arguments in favor of formalizing the Anthropocene include changing patterns of erosion brought on by acid rain, ocean acidification, the introduction of invasive plant species, the presence of manmade chemicals in soil layers following the invention of modern polymers (plastics, vulcanized rubber, and other molecules composed of long chains of hydrocarbons), widespread deforestation and an increase in the presence of charcoal due to the invention of fire, an alteration of the Earth’s albedo with the expansion of urban environments, and chemical changes to our atmosphere as the result of industrial pollution.


The term "Anthropocene" was coined by biologist Eugene Stoermer in the 1980s and brought to the forefront in 2000 by Nobel Prize-winning atmospheric chemist Paul Crutzen.


The exact start date for the Anthropocene is up for debate, but there are several popular contenders. One leading candidate is July 16, 1945—the date of the Trinity test, when the world’s first atomic bomb was detonated. Though an obviously significant event—and one that has left a lingering mark on the geologic record due to the formation of trinitite (atomic glass) on the site—other earlier dates, such as the beginning of the Industrial Revolution, or the mass migration of our species out of Africa, have been proposed. I would submit that a fitting date to begin the Anthropocene is 1909—the year that chemist Fritz Haber successfully fixed nitrogen from Earth’s atmosphere into ammonia. Following, this method was used on a large scale by industrial chemist Carl Bosch [To learn more about how the Haber process works, check out this video from the Fuse School.]

Fritz Haber successfully combined nitrogen in the air with hydrogen to create ammonia, which is how we create fertilizer. The implications were far more wide-reaching than what anyone might have imagined in terms of the world's food production and its ultimate effects on the environment.  

Fritz Haber successfully combined nitrogen in the air with hydrogen to create ammonia, which is how we create fertilizer. The implications were far more wide-reaching than what anyone might have imagined in terms of the world's food production and its ultimate effects on the environment.  

Before the Haber process, farmers were restricted in where they could successfully grow crops. Though nitrogen naturally cycles into the soil through the action of lightning strikes and specialized bacteria, the natural process takes many years and is restricted by the presence of good soil conditions. As a vital nutrient necessary for all life and a key component of gunpowder, securing good sources of nitrogen to feed their growing empires became a priority for colonial Europe by the end of the 19th century, and natural sources were dangerously rare.

One such source, guano, was so precious that wars were fought to secure it. The War of the Pacific, fought between Bolivia, Peru, and Chile from 1879 to 1883, was primarily over control of the coastline of the Atacama Desert, where significant deposits of guano from seabirds had accumulated over thousands of years. It was Chile’s victory and subsequent annexation of Bolivia’s coastal territories that doomed the country to become one of Earth’s few landlocked nations.

Even the United States wanted in on the guano market, passing the Guano Islands Act in 1856, which empowers any citizen of the United States to claim as sovereign territory for their country any unclaimed island found to contain guano deposits. This mad scramble for bird droppings may seem silly today, but at the time it was common knowledge that the supply of available nitrogen was dwindling, and once it ran out mass starvation would doom millions.

This doomsday scenario prompted Robert Malthus to envision widespread famine in India by the end of the 20th century due to the limited availability of plant fertilizer. The Haber process likely saved our species from terminal environmental damage; some estimates based on 19th-century farming practices indicate that without widely available and sustainable fertilizer, humanity would need to plow under almost half of the Earth’s surface just to feed our numbers.

The importance of Haber’s discovery is even found in your own body. Some estimates indicate that up to 80 percent of the nitrogen in any given human being on Earth is derived directly from the Haber process. Thanks to Haber’s invention, our species has undergone significant social evolution: increases in farming efficiencies allowed for the mass migrations to the city that shaped the 20th century, and our population rose from just shy of 2 billion to 7 billion in less than a century.

But even more significant is how the Haber process has changed life on Earth, because the available amount of nitrogen directly corresponds to the biomass production in a region. Farm runoff now accounts for a good portion of the biologically available nitrogen on the planet, leading to mass algal blooms around the globe, and with farming no longer restricted to very specific areas, food production is now possible in previously untouched environments, such as Brazil’s Cerrado.

One can liken the invention of the Haber process to an event as significant as the oxygenation of Earth’s atmosphere by photosynthetic bacteria, a fundamental shift in how life interacts with Earth’s basic chemistry. Such a distinction surely makes the Haber process’ birthday a suitable candidate for the start of the Anthropocene.



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