Donald Worster, environmental historian

The worst environmental catastrophe in Earth’s history occurred 66 million years ago, when an asteroid struck, killing an estimated 70 percent of all species. Nothing humans have done compares. But the 1930s Dust Bowl was the worst catastrophe in America’s history, and such a phenomenon may become global as the world’s climate changes.


John McNeill, history professor, Georgetown

The deliberate rupture of the dikes on China’s Yellow River in 1938, by Chinese troops trying to halt a Japanese advance. It killed half a million Chinese, displaced millions more, and led to a decade of flooding.


Graham Roumieu

David Yarnold, president and CEO, National Audubon Society

DDT was a human-made environmental disaster that caused the shells of bird eggs to thin, which crushed populations—and harmed the food chain in ways that affected humans.


John Schwartz, science writer, The New York Times

It would be hard to beat the six-mile-wide asteroid that struck Earth about 66 million years ago with an explosive force billions of times more powerful than that of the atomic bomb the United States dropped on Hiroshima.


Bill McKibben, author and environmentalist

The asteroid strike that some scientists theorize wiped out the dinosaurs was pretty significant. Of course, with climate change we’re on the path to accomplishing something on the same scale, and this time it’s entirely voluntary.


Jon Jarvis, former director, National Park Service

The Deepwater Horizon blowout spewed boiling-hot oil like a fire hose for 87 straight days, and every day was Groundhog Day, requiring teams to repeat cleanup of the same hundreds of miles of shoreline as oil smothered beaches, coastal wetlands, and countless birds.


Carter Roberts, president and CEO, World Wildlife Fund

During the Permian–Triassic mass extinction, or the Great Dying, skyrocketing temperatures wiped out nearly all the species on Earth. Most forms of life never fully recovered.


Elizabeth Kolbert, author, The Sixth Extinction

The end-Permian extinction, which took place about 250 million years ago, killed off something like 90 percent of all species around at the time. The event, sometimes called the Great Dying, brought the Paleozoic era to a dismal close. It was probably caused by a massive release of carbon dioxide—a warning if ever there was one.


Grahm Roumieu

J. Samuel Walker, author, Prompt & Utter Destruction World War II destroyed fields and forests, polluted waterways, and produced urgent demand for raw materials. The environmental catastrophes it created in vast sections of Europe and Asia caused countless civilian deaths.


Brian Black, Distinguished Professor of History and Environmental Studies at Penn State

The Anthropocene—the geological epoch in which humans’ impact has come to define Earth’s future—began with the acceleration enabled by the industrial use of fossil fuels and continues today through our living patterns and the waste that we produce. Fortunately, humans can realize the implications of our impact, which holds the only true promise for us to save our species.


Carol Browner, former administrator, EPA

Climate-science denial.


Matthew Michael Carnahan, screenwriter, Deepwater Horizon and World War Z

It hasn’t happened yet.


Reader Responses

John Short, Bend, Ore.

The deforestation and soil degradation that contributed to the collapse of the Roman empire. The creation of Rome and the care and feeding of its soldiers laid waste to much of the continent’s agricultural land, resulting in low population for 1,000 years.


Adrienne Moravec, Falls Church, Va.

The Irish potato famine of the 1840s and ’50s. Due to poor agricultural practices compounded by cruel and inept British land management, a disease affecting a single crop caused the deaths of more than 1 million Irish and the emigration of another 1.1 million people.


Allan Havis, La Jolla, Calif.

The Chernobyl nuclear disaster, which killed 31 people in three months and released 400 times more radioactive material than the Hiroshima atomic bombing.


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