President's Note, March 2024

Written by John Seager, President and CEO | Published: March 11, 2024

My years in politics often took me to the Democratic stronghold of Levittown, Pennsylvania, with its 17,000+ homes. Built to accommodate the post-World War II baby boom, it’s often considered one of the U.S.’s first planned communities, along with its Long Island twin. But there is an asterisk.

Seven centuries before Jamestown and Plymouth Rock, a planned city dubbed Cahokia rose up in what is now the American Midwest when dramatic increases in rainfall produced bumper crops of maize. According to Broxton Bird, a climatologist at Indiana University–Purdue University Indianapolis, “That comes at right around 950 [C.E.] and that’s around the time the population at Cahokia explodes.” Cahokia grew rapidly to the point where it may have rivaled London and Paris in that era in terms of size. Along with its environs, Cahokia was home to perhaps as many as 40,000 people.

No one knows what its residents called their city. The name Cahokia is derived from the tribe of the same name which arrived in that area centuries later. There are no known links between any tribe and the largest pre-Columbian city north of Mexico.

Cahokia’s wooden walls encircled modest dwellings amidst expansive plazas surrounded by flat-topped pyramids up to 100 feet high. Situated across the Mississippi River from present-day St. Louis, the city was a major center for trade and commerce. Raw materials arrived from as far away as Lake Superior, the Carolinas, and Oklahoma.

Cahokia thrived for about 400 years. Then its population collapsed and it ceased to exist. Cahokia’s fall coincided with rapid climatic changes, resulting in “profound drought,” according to Dr. Bird. A recent study by researchers at the University of Ottawa supports the theory that “climate change, a large-scale phenomenon, was implicated in Cahokia’s collapse.”

Only massive earthen mounds remain where thousands of people once lived and worked. Will we follow our own version of Cahokia’s fate as rapid modern population growth abetted by massive use of fossil fuels triggers climate chaos? More broadly, our reckless expenditures of natural capital by 8 — soon-to-be 9, then 10 — billion people can’t go on forever. We’ve exceeded Earth’s carrying capacity as did Cahokia in its own corner of the world. It thrived. Then it vanished.

While demographers disagree on how population trends may play out over the remainder of the 21st century, there is cause for hope with the shift to lower fertility rates, especially in more developed nations. Regrettably, the positive impact of smaller families is ignored by many deeply concerned about greenhouse gas emissions, when it should be championed.

While we may never know the full story behind Cahokia’s collapse, our own tale unfolds every day. We can begin a new chapter by stopping population growth through proven voluntary approaches so that humans and nature can thrive together.

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