Paul Ehrlich, often called alarmist for dire warnings about human harms to the Earth, believed scientists had a responsibility to speak out

Stanford University biologist Paul Ehrlich, who died March 15, 2026, in Palo Alto, California, was a scientific crusader whose dire predictions about population growth, world hunger and environmental collapse made headlines and sparked controversy for decades.

Sometimes called a “prophet of doom” by his detractors, Ehrlich was among the most public figures of the environmental movement. He was admired and often honored for his prophetic warnings. But he was also excoriated when his worst predictions failed to come true.

Ehrlich founded Stanford’s Center for Nature and Society in 1984 and wrote more than 40 books and over 1,100 scientific articles on ecology, the environment and population dynamics. He is best known outside of academia for writing “The Population Bomb” in 1968, along with his wife, conservation biologist Anne H. Erhlich, who survives him.

The book became a bestseller that was reprinted more than 20 times and translated into multiple languages. It starkly predicted that population growth would exhaust Earth’s resources, leading to wars and social collapse.

Ultimately, the book both popularized and polarized the U.S. environmental movement.

As a scholar of communications and environmental history, I see Ehrlich’s difficult fight for the environment as emblematic of the vast chasm between science on one side and political culture influenced by the mass media on the other side.

And I see Ehrlich’s passing – along with others of his generation, such as Carl Sagan, E.O. Wilson and Jane Goodall – as a loss for a world that needs visionaries and public scientists now more than ever. Public understanding of science and technology is critical for political discussion, for environmental preservation and, in the words of British physical chemist C.P. Snow, for the sake of “the poor who needn’t be poor if there is intelligence in the world.”

The battle over the book

“The Population Bomb” opened with a verbal blast: “The battle to feed all of humanity is over.” And because the “stork had passed the plow,” the Ehrlichs wrote, “hundreds of millions of people are going to starve to death.” Overpopulated India was doomed, they contended, and England “will not exist in the year 2000,” following a massive social and environmental breakdown.

These stark warnings, while overstated, seemed at least plausible at the time. Older scientists, including Snow and oceanographer Roger Revelle, had also warned about population growth overtaking food production.

The Ehrlichs were influenced by books such as the 1948 bestsellers “Road to Survival,” by ecologist William Vogt, and “Our Plundered Planet,” by paleontologist Henry Fairfield Osborn. All of these thinkers owed a debt to the original Cassandra of population catastrophe, English economist Thomas Malthus, whose 1798 book “An Essay on the Principle of Population” warned that the world’s population would inevitably outstrip its food supply.

Even worse, Malthus predicted, efforts to produce more food would simply continue the cycle of famine and poverty. However, new crops and agricultural techniques forestalled Malthus’ catastrophe in the 19th century. As a result, the term “Malthusian” came to signify overly pessimistic views about complex social problems.

A different sort of Malthusian

Handsome and well-spoken, Ehrlich captured the public imagination through news articles, public lectures and television appearances. “The Population Bomb” launched him into the center of a raging global debate over environment and conservation. He appeared as a guest on “The Tonight Show” with Johnny Carson more than 20 times in the 1970s and early ’80s.

This wasn’t the typical public profile for a biology professor. As New York Times reporter Robert Reinhold observed in 1969, Ehrlich was “representative, perhaps, of a growing new breed of scientists who are willing to get involved in the unscientific and sometimes rough business of crusading in public against such things as DDT, highway building and population growth.”

Not all environmental advocates agreed with Ehrlich’s view that population growth was the critical threat. Another prominent biologist, Barry Commoner, saw faulty technology as the primary source of environmental problems.

In fairness, Ehrlich and his frequent collaborator, physicist John Holdren, saw technology and population as cofactors in a complex social problem, which they summarized with the equation I = P x A x T, or Impact equals Population times Affluence times Technology. Put another way, population growth, wealth and the types of technologies people chose to use all contributed to human impacts on the environment.

The debate between Ehrlich and Commoner perplexed some people, but it showed two different approaches to environmental policy. With Commoner’s approach, technological problems such as toxic waste and nuclear radiation, would be solved through cleanups and improved processes.

Ehrlich said reducing overconsumption and addressing population growth would also help ease these challenges. To slow population growth, Ehrlich called for promoting contraception and increasing access to abortions, and perhaps even resorting to coercive methods, such as forced sterilization.

By the 1970s, a focus on population growth had become widely accepted. The first United Nations Conference on the Human Environment, held in Stockholm in 1972, ranked population growth alongside pollution and underdevelopment as the top action items on the global agenda. Later that year, a prominent European think tank, the Club of Rome, echoed Ehrlich’s warnings in its widely circulated Limits to Growth report.

Scarcity or abundance?

World population continued to grow through the 1970s and ’80s, but the impacts that Ehrlich predicted did not occur. This was largely due to the Green Revolution, a broad campaign by governments and research institutes to provide high-yield varieties of wheat and rice, along with pesticides and mechanized agriculture, to developing countries. These new tools increased harvests and dramatically reduced the risk of famine.

Agricultural scientist Norman Borlaug, a leader of this effort, received the Nobel Peace Prize in 1970. Borlaug made a point of agreeing with Ehrlich in his Nobel lecture, saying the Green Revolution was a temporary reprieve and that population control was also essential in the ongoing battle against hunger.

Conservative economists and scientists weren’t persuaded. One prominent critic, academic economist Julian Simon, argued for what came to be called the cornucopian view, which held that the only limits to growth were imagination and ingenuity. Simon said the Earth had infinite capacity to provide materials and that humans would constantly innovate and find new ways to use them.

In 1980 Simon publicly bet Ehrlich that prices of five important industrial raw materials – copper, nickel, tungsten, chromium and tin – would fall rather than rise over the next decade. Ehrlich said he would have preferred some environmental measure rather than metals, but he said resources would become scarce and prices would rise.

Simon, on the other hand, argued that markets and new technologies would drive prices down. Ultimately, although prices for these five metals had risen during the preceding decades and would also rise during the 1990s, they declined between 1980 and 1990. Simon won the bet, and Ehrlich wrote him a check in 1990 for US$576.07, the difference between the 1980 and 1990 prices.

A matter of when

After the catastrophes that Ehrlich predicted in “The Population Bomb” failed to occur, many critics had a laugh at his expense. “As you may have noticed, England is still with us. So is India,” chuckled New York Times columnist Clyde Haberman in 2015.

“Paul Ehrlich is a misanthrope who’d make you apply for a government permit to have a baby if he could,” wrote Chelsea Follett of the libertarian Cato Institute in 2023.

Ehrlich and his supporters replied that while the Green Revolution might have forestalled widespread famine, human impacts were weighing ever more heavily on the planet. Taking problems such as climate change and toxic pollution into account, Ehrlich asserted in 2009 that “The Population Bomb” had been “way too optimistic.”

In his 2023 memoir, “Life,” Ehrlich expressed deep gratitude for a 70-year career in science. However, he was frustrated over what he saw as the inability of science to penetrate America’s stubbornly unscientific political culture. He was also saddened that the environmental movement was failing to effectively oppose “the forces that pose existential threats to civilization.” Throughout his career as a public scholar, Ehrlich was never afraid to look into the abyss.

William J. (Bill) Kovarik does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.