This study is led by Prof. Yong WEI (Institute of Geology and Geophysics, Chinese Academy of Sciences).
Most of the energy of the Earth system is sourced from the Sun. People might therefore wonder: are changes in the Earth's biosphere related to solar activity? An epidemic is a highly contagious and widespread disease that significantly impacts the development of human society. Many severe epidemics had catastrophically destroyed human lives and even civilizations in history.
During the historical civilization of ancient China, the records of epidemics are abundant but intricate. The records of epidemics for the past 2000 years were compiled and analyzing these data can help people find some principles for the modern human healthcare system. This study collects the epidemic records from AD 0 to 1840 to explore the relationship between epidemic and solar activity (see the image below).
In order to investigate the relationships between epidemic indices and solar activity, the team applied the wavelet analysis and ensemble empirical mode decomposition. Results of wavelet analysis illustrate that solar activity and epidemics have highly consistent variations in long-term trends and short-term cycles. From the ensemble empirical mode decomposition results, it can be roughly seen that they are consistent with the wavelet results.
The impact of solar activity on the epidemic may be diverse, resulting from the superposition of global and regional influences. In different phases of solar activity, the change of the Sun itself is not unilateral. Therefore, the relationship between solar activity and epidemic may depend on the this phase, which could be caused by both the Sun and the Earth.This question requires more long-term investigations and historical data to comprehensively understand the impact of solar activity on the Earth and its biosphere.
This study uses long-term epidemic data from Chinese historical books to analyze the relationship between epidemic and solar activity. The results show that the epidemic index and sunspot number have similar periodic changes; the long-term trend consistency is also apparent in the non-high frequency signal. Of course, the factors affecting epidemics are diverse and complex, and more interdisciplinary research is needed in the future. This study promotes further studies of long-term changes in the epidemic, and lays a foundation for the future search for the relationship between epidemic and solar activity changes and for the mechanism of long-term changes in epidemic to provide early warning features to humans.
See the article:
Chen S, Wei Y, Yue X, Xu K, Li M, Lin W. 2023. Correlation analysis between the occurrence of epidemic in ancient China and solar activity. Science China Earth Sciences, 66(1): 161–168, https://doi.org/10.1007/s11430-022-9986-5
