Generational amnesia shapes how communities remember past climate extremes

Researchers from the Max Planck Institute of Geoanthropology and several Chinese universities analyzed historical records to see how human memory influences perceptions of past weather.

The team examined official histories, diaries, and inscriptions from 32 sites in the Yellow River Basin of northern China. They compared these human records against tree-ring data, which provides an objective history of rainfall and river flow unaffected by human observation.

The study found that historical writers often exaggerated the severity of weather events based on how they compared to recent years. This suggests that people did not record objective weather but instead recorded how a year felt relative to what they and their peers remembered. The researchers discovered that these written records align most accurately with objective data over a period of 20 to 40 years. This timeframe corresponds to the average life expectancy in historical northern China.

The team used an agent-based model to show that this pattern occurs because each generation resets its baseline for what is normal based on their own lived experiences. This phenomenon, known as generational amnesia, means that people tend to forget extreme events that occurred before they were born. The authors suggest that understanding this memory filter helps explain why risk awareness can fade between disasters as older generations pass away.