In the century after Europeans arrived in the Americas in the late 1400s, more than 50 million Indigenous people are estimated to have died from epidemics, warfare, and slavery. This human-caused tragedy, also known as the Great Dying, may also have left its mark on the landscape and climate.

In a 2019 analysis, U.K. researchers proposed that the regrowth of forests in places where Native people had cleared the land may have absorbed and stored enough carbon to contribute to a 17th-century dip in global atmospheric CO2 levels. This anomaly is thought to be one of the causes of an unusually cold period known as the Little Ice Age.

But a study published last week in the journal