In the past 150 years, humanity has faced a plethora of calamities. The first half of the 20^th century was a horror show, with two world wars alone killing upwards of 100 million people and the influenza epidemic of 1918 and 1919 killing as many as 50 million others. But before these mass casualties plagued the human race, a comparatively unknown global catastrophe wiped out millions of people in just three years. From 1876 until 1878, a global famine wreaked havoc on Asia, South America, and Africa, cutting short the lives of an estimated 50 million people.

“It was arguably the worst environmental disaster to ever befall humanity and one of the worst calamities of any sort in at least the last 150 years,” the authors of a 2018 research article in the Journal of Climate wrote in their paper. “In a very real sense, the El Niño and climate events of 1876–78 helped create the global inequalities that would later be characterized as ‘first world’ and ‘third world.’”

Most are familiar with the mechanisms behind the El Niño/La Niña cycle in the Pacific Ocean, known more formally as the El Niño-Southern Oscillation (ENSO). Normally, trade winds across the Pacific Ocean move east to west, helping to build up warm waters in the western Pacific. In other years, these trade winds weaken, which causes the usual upwelling of cold water near South America to stop. In North America, this typically means warmer weather in the Northwest and Midwest and flooding conditions in the Southwest and down into Florida. La Niña, as you might expect, is the opposite—trade winds are stronger than usual, pushing more warm water toward Asia and bringing colder, wetter conditions to the northern U.S. and drier, warmer conditions in the American south.

In 1877, the world began experiencing a particularly strong El Niño. According to the Minnesota Department of Natural Resources, the state recorded its warmest winter on record, with an average temperature of 29 degrees Fahrenheit in the Twin Cities—a record that wasn’t surpassed until 2023 (which was also fueled by a particularly strong El Niño). Across the world, countries experienced severe droughts that instigated devastating famines. But while the strong El Niño event has long been considered the primary culprit, more recent research paints a more nuanced picture. In other words, a lot of bad luck coalesced at just the right time to create a global catastrophe in 1877-78.

The authors of the 2018 article note that years of preceding cool tropical Pacific conditions, coupled with a record strong Indian Ocean dipole (another climate phenomenon similar to ENSO) and abnormally warm Atlantic Ocean surface temperatures, created the perfect conditions for a strong El Niño event. Human shortsightedness was then able to deliver the killing blow.

“The triggers for the famine were acute droughts, but political and economic factors, especially the neglect or destruction of traditional systems of water and grain storage, were responsible for translating crop failure into unprecedented mass mortality,” the authors wrote.

While it might be tempting to shrug off this climate event as a fluke, a 2020 study in the same Journal of Climate found that in statistical terms, the strength of the 1877-78 El Niño was not significantly greater than three other super El Niño events in 1982-83, 1997-98, and 2015-16. Now, the world is preparing to enter a new El Niño era further exacerbated by warmer temperatures caused by climate change. Luckily, according to The New York Times, modern agriculture tracks these ENSO changes, and no one is predicting a large-scale famine this time around. But that doesn’t mean this new EL Niño is without risks, and today, countries around the world are still taking lessons from the global devastation 150 years in the past.

“It gives us an idea of how to be better prepared,” Vimal Mishra, a civil engineer at the Indian Institute of Technology Gandhinagar, told the New York Times, referring to the Great Famine. “It shows you, this is the worst that could happen.”