Hatches of Rocky Mountain locusts (Melanoplus spretus) in 1874 and 1875 brought swarms up to 1,800 miles long and 110 miles wide across the Great Plains. Numbers were estimated in the trillions. Farmers risked starvation. The swarm is believed to have been the largest mass of living insects ever witnessed by modern man—but within thirty years the species disappeared. “I can’t believe M. spretus is extinct,” said ecologist Dan Otte in 2014. “But where to look for it?”

Bibliophilic bishop Richard de Bury lamented the burning of the Library of Alexandria. “Who would not shudder at such a hapless holocaust, where ink is offered up instead of blood,” he wrote in 1344, “where the devouring flames consumed so many thousands of innocents?”

In 1919 a steel storage tank burst in Boston and spilled 2.3 million gallons of molasses, creating a twenty-five-foot-high wave that killed twenty-one people and tore buildings from foundations. The tank had leaked since its installation, but the company had, in response to complaints, merely painted it a concealing brown.

The first mass extinction on earth occurred around 2.5 billion years ago, when a photosynthesizing bacterium appeared and released so much oxygen into the atmosphere that anaerobic life was largely wiped out. This is often called the Great Oxygenation Event, the Oxygen Catastrophe, or the Oxygen Holocaust. 

Plutarch related that news of the Athenians’ brutal defeat at Syracuse during the Peloponnesian Wars first came from a stranger who told the story at a barbershop “as if the Athenians already knew all about it.” When the barber spread the news, city leaders branded him a liar and an agitator. He was “fastened to the wheel and racked a long time.” Official messengers later came with the “actual facts of the whole disaster,” and the barber was released.