Ancient shell data reveal shifts in tropical cyclone patterns over 3,000 years

Lisa Lock
scientific editor

Robert Egan
associate editor

Tropical cyclones (TCs) rank among the most destructive weather phenomena, often bringing intense winds, heavy rainfall, and massive storm surges.
Historically, efforts to unravel the link between TCs and climate change have been constrained by the short span of observational data, which typically covers fewer than 100 years. This limitation has clouded our understanding of long-term trends and variations in TC activity, making it critical to study how TCs responded to past climate shifts to better predict their behavior amid ongoing global warming.
To tackle this challenge, a research team led by Prof. Yan Hong from the Institute of Earth Environment of the Chinese Academy of Sciences, has developed the first daily-resolution proxy dataset to investigate prehistoric TC activity. The research, in npj Climate and Atmospheric Science, draws on a 12-year growth record from a fossil Tridacna shell—a 3,000-year-old bivalve unearthed in the northern South China Sea.

The analysis revealed striking differences from modern patterns: TCs 3,000 years ago were approximately 15% more frequent and peaked in summer, unlike today's autumn-dominant storms.
Combining their findings with other paleoclimate records, the researchers suggest the seasonal shift was likely tied to a northward migration of the Intertropical Convergence Zone, which created conditions favorable for TC formation and development. The study offers new insights into the mechanisms driving seasonal changes in TC activity.
More information: Nanyu Zhao et al, Prehistoric shifts in tropical cyclone season in the South China sea: evidence from daily resolution records of giant clam shells, npj Climate and Atmospheric Science (2025). .
Journal information: npj Climate and Atmospheric Science
Provided by Chinese Academy of Sciences