For much of the 20th century, winter brought an annual ritual to Princeton, New Jersey. Lake Carnegie froze solid, and skaters flocked to its glossy surface. These days, the ice is rarely thick enough to support anybody wearing skates, since Princeton’s winters have warmed about 4 degrees Fahrenheit since 1970. It’s a lost tradition that Grace Liu linked to the warming climate as an undergrad at Princeton University in 2020, interviewing longtime residents and digging through newspaper archives to create a record of the lake’s ice conditions.

When the university’s alumni magazine featured her research in the winter of 2021, the comment section was filled with wistful memories of skating under the moonlight, pushing past the crowds to play hockey, and drinking hot chocolate by the frozen lakeside. Liu began to wonder: Could this kind of direct, visceral loss make climate change feel more vivid to people?

That question sparked her study, recently published in the journal Nature Human Behavior, that came to a striking conclusion: Boiling down data into a binary — a stark this or that — can help break through apathy about climate change.