Climate and weather drivers increase landfalling typhoons during the Maunder (Solar) Minimum

Tropical cyclones are among the most powerful forces on Earth, capable of reshaping coastlines and disrupting lives across entire regions. In the Western Pacific, where these storms are most frequent, scientists have long struggled to understand why their numbers rise and fall over decades. The modern satellite record, which provides our most reliable data, spans only about forty-five years. This short window makes it difficult to separate natural fluctuations from the effects of human activity, such as greenhouse gas emissions. To see the bigger picture, researchers must look much further back in time, into eras before industrialization, when the climate was driven by natural forces alone. One such era was the Maunder Minimum, a period roughly between 1650 and 1680 when the Sun was unusually quiet, producing very few sunspots and sending less energy to Earth. This time coincided with the coldest phase of the "Little Ice Age," a centuries-long stretch of cooler global temperatures. Understanding how the climate behaved during this quiet solar period offers a unique window into how the Earth's weather system responds to natural changes, independent of modern pollution.

A team of researchers has now combined ancient Chinese records with modern artificial intelligence to solve a mystery from this era: why did so many typhoons make landfall on the coast of China between 1651 and 1680? The answer lies in a rare convergence of two factors: a shift in the global climate pattern and a roll of the dice in the atmosphere's daily weather. By bridging digitized historical documents with powerful computer simulations, the study reveals that the Sun's dimming altered the temperature difference between the tropics and the poles, strengthening the global air circulation that fuels storms. At the same time, random variations in the weather pushed the birthplaces of these storms closer to the Chinese coast, turning a general increase in storm activity into a specific spike in landfalls.

The story begins with a remarkable historical record known as REACHES, which compiles handwritten accounts from Chinese officials dating back to the Ming and Qing dynasties. These records meticulously document extreme weather events, including the monthly number of tropical cyclones hitting the country's east and south coasts. The data shows a striking, unprecedented peak in landfalls during the Maunder Minimum, a period when the Sun was at its weakest. To understand why this happened, the researchers turned to the Ai2 Climate Emulator Version 2, a sophisticated artificial intelligence model trained on modern weather data. Unlike traditional climate models that can take months to run a single century of simulation, this AI tool can generate hundreds of years of climate history in a matter of hours. The team used it to create a large collection of possible climate scenarios for the period between 1500 and 1850, forcing the model with reconstructed data on ocean temperatures and sea ice from that time.

The simulations confirmed what the historical records suggested: the Western Pacific saw a significant increase in tropical cyclone activity during the Maunder Minimum. However, the computer models revealed that this increase was not just a simple reaction to cooler temperatures. The researchers found that the dimming Sun cooled the high-latitude regions of the Northern Hemisphere much more than it cooled the tropics. This created a steeper temperature difference between the equator and the poles. In the atmosphere, a steeper temperature gradient acts like a steeper hill, causing the air to move more vigorously. This intensified the Hadley circulation, a massive global loop of air that rises near the equator and sinks in the subtropics. A stronger Hadley circulation creates more favorable conditions for the formation of "seed disturbances"—the initial swirls of air and moisture that can grow into full-blown typhoons. The simulations showed that this mechanism alone increased the total number of storms in the Western Pacific by nearly ten percent.

Yet, a higher number of storms in the ocean does not automatically mean more storms hitting the coast. The path a storm takes depends heavily on where it is born and how the winds steer it. The researchers discovered that the specific spike in landfalls along China's southern coast was driven by a different factor: randomness. In the years between 1651 and 1680, the weather conditions in the atmosphere happened to favor the birth of storms in a specific location—just east of the Philippines and over the South China Sea. When storms form in this spot, the prevailing winds naturally push them northwestward, directly toward the southern coast of China. The study found that this shift in birthplace was not caused by a predictable change in the large-scale wind patterns, which actually tended to steer storms away from the coast. Instead, it was the result of chance variations in the weather, a kind of atmospheric noise that determined exactly where the storms would form.

To test how much of this was due to the climate versus the weather, the team ran hundreds of simulations. They found that while the climate changes (the dimming Sun and the resulting ocean temperature patterns) increased the total number of storms across the entire ocean basin, only a few specific simulation runs reproduced the exact pattern of landfalls seen in the Chinese records. In most of the simulations, the storms formed in slightly different places and missed the coast, even though the total number of storms was high. This suggests that the massive spike in landfalls recorded in history was a "perfect storm" of two things: a climate that made more storms overall, and a lucky (or unlucky) roll of the weather dice that placed those storms on a collision course with the coast. The researchers noted that this role of random weather variations in driving long-term changes is often overlooked, as scientists typically focus on large-scale climate drivers like ocean temperatures.

The study also addressed and ruled out several other theories that had been proposed to explain this historical peak. Some earlier ideas suggested that the storms were caused by a La Niña pattern, where the eastern Pacific is cooler than usual, or by a southward shift in the band of rain clouds near the equator. The new analysis, however, showed that the ocean temperatures during this period actually resembled an El Niño pattern, with warmer waters in the east and cooler waters in the west. Furthermore, the data did not support the idea that the large-scale steering winds had changed in a way that would push more storms toward the coast. The evidence points clearly to the combination of a climate-driven increase in storm numbers and a weather-driven shift in storm birthplaces.

This finding has implications that extend far beyond the history of Chinese typhoons. The study demonstrates that random weather events can leave a lasting imprint on climate trends over decades, a concept that challenges how scientists project future storm risks. If natural randomness plays such a large role in the past, it must be carefully accounted for when predicting how storms will behave in a warming world. The research also highlights the potential dangers of solar radiation management, a proposed geoengineering technique that involves dimming the Sun to cool the planet. The simulations suggest that reducing sunlight could inadvertently strengthen the global air circulation and increase the frequency of typhoons in the Western Pacific, even if it successfully lowers global temperatures.

The ability to uncover these details relied on a unique collaboration between history and technology. By using the AI emulator to run thousands of years of simulations and comparing them against the precise, daily records kept by Chinese officials centuries ago, the researchers were able to isolate the specific drivers of this historical event. The study confirms that the Maunder Minimum was a time of heightened tropical cyclone activity, driven by a cooler Sun that reshaped the global temperature gradient. But it also shows that the specific impact on human populations depended on the chaotic, unpredictable nature of the weather itself. As the authors note, understanding these natural variations is essential for separating the signal of human-induced climate change from the noise of natural variability, ensuring that future projections of storm risks are as accurate as possible. The work serves as a reminder that the climate system is a complex interplay of steady, long-term forces and fleeting, random events, and that both must be understood to grasp the full story of our changing world.