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 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, published 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.

This work was supported by the National Natural Science Foundation of China, and the National Key R&D Program of China, among other sources.