Geomagnetic excursions over the past 10 000 years revealed in peat deposits
A new study published in the Russian Journal of Pacific Geology looks into geomagnetic excursions over the last 10 000 years utilizing peat deposits from Russia’s Khabarovsk Territory. The study called into attention the importance of understanding these transitory shifts in Earth’s magnetic poles, which differ from total geomagnetic reversals and impact climatic and environmental circumstances.
Image credit: Aleksey Peskov
- Inversions (geomagnetic reversals) are major shifts where Earth’s magnetic poles completely reverse, occurring over long intervals, while excursions are more frequent, temporary disturbances in the magnetic field that do not result in a full pole reversal.
- The study found that the youngest known excursion occurred 2 500 years ago, consistent with historical reports of northern lights experienced at odd latitudes and cooling occurrences described in sedimentary strata from Israel.
- The study brought attention to the fact on how geomagnetic field fluctuations may correspond with periods of climate cooling and other key environmental occurrences.
- Research on changes (variations) in the Earth’s magnetic field and forecasts regarding its future behavior are becoming especially relevant and are forming a new scientific trend in world science.
A recent study conducted by Dr. Aleksey Peskov, Director of the Kosygin Institute of Tectonics and Geophysics of the Far Eastern Branch of the Russian Academy of Sciences (ITiG FEB RAS), has made substantial progress in comprehending Earth’s magnetic field fluctuations over the last 10 000 years.
This study, published in the Russian Journal of Pacific Geology, used peat deposits to provide new information about historical geomagnetic behavior offering a better understanding of past, and future, geomagnetic and climatic shifts.
Two key terms essential to understanding the Earth’s magnetic field are “inversion” (geomagnetic reversal) and “excursion.”
Inversions refer to major shifts where the magnetic poles switch places, with the last such event occurring around 780 000 years ago. The frequency of these inversions varies widely, from tens of thousands to millions of years. In contrast, excursions are more subtle variations in the magnetic field and were discovered by scientists only a few decades ago. These excursions occur much more frequently than inversions but can significantly impact climate and environmental circumstances on the planet.
Dr. Peskov’s research focused on geomagnetic excursions by looking at peat deposits from the Khabarovsk Territory, which have a thorough and continuous record of geomagnetic variations over the last 10 000 years.
In an email exchange with The Watchers, Dr. Peskov explained, “The main problem of studying records of the Earth’s magnetic field in the past is the search for objects in which this record is well preserved.”
“For the fine structure of the geomagnetic field (excursions and other “fast” variations), rocks are not a very good object, since the duration of such variations and the rate of fixation of magnetization in rocks can often coincide, so the magnetic record of excursions in rocks is absent or presented incompletely.”
“In our research, we found that peat deposits are a good and promising object for studying the fine structure of the field, in which the record of geomagnetic field variations in the Holocene is most fully presented.”
The Holocene is the current geological epoch, which began approximately 11 700 years ago after the end of the last Ice Age. It marks a period of relatively stable and warmer climate, during which human civilization developed and flourished. This epoch is part of the Quaternary period and represents an interglacial phase within Earth’s ongoing cycles of glaciation.
It’s important to note that in 2019, the US National Geophysical Data Center (NGDC) updated the International Geomagnetic Reference Field (IGRF) earlier than scheduled due to significant errors of up to 40 km (24.85 miles) in calculating the position of the planet’s magnetic poles.
“This was a consequence of a sharp increase in the drift speed of the north magnetic pole,” Peskov said.
In the 1970s, the speed of the north magnetic pole was 10 km (6 miles) per year, but by 2015, it had increased almost fivefold, reaching 48 km (30 miles) per year.
“Therefore, today, research on changes (variations) in the Earth’s magnetic field and forecasts regarding its future behavior are becoming especially relevant and are forming a new scientific trend in world science,” Peskov said.
“To understand the future, it is necessary to have a good understanding of how these events occurred in the past. This is exactly the kind of research that is being conducted in the Khabarovsk Territory, at our Institute.”
A magnetic excursion is an incomplete inversion, where the poles begin to shift but return to their original positions. It’s a sudden change in the characteristics of the magnetic field, which can lead to climate changes on Earth.
The most recent magnetic excursion occurred 2 500 years ago, during which the North Magnetic Pole moved to southern latitudes before returning to its original position. This event is indirectly supported by research from Japanese scientists. In 2019, they published a study based on ancient Assyrian clay tablets that contained records of the northern lights seen over Assyria 2 500 years ago.
These sightings occurred at 30 – 40 degrees north latitude, where auroras are not seen today due to the current position of Earth’s magnetic poles.
Additionally, studies of oxygen isotopes in sedimentary rocks from Israel show significant cooling on Earth 2 500 years ago.
Numerous studies have demonstrated a connection between variations in Earth’s magnetic field and climate changes. Furthermore, Italian and British scientists recently conducted experiments proving that magnetic field reversals affect plant evolution by influencing gene expression rates.
They even produced a short film on the topic, and you can watch it below:
One of the study’s primary results is a clear link between the 1 700-year harmonic and multiple Bond events, which are significant climatic occurrences associated with changes in global temperature and environmental circumstances.
This correlation showed a possible link between geomagnetic behavior and climate change. Such findings enhance the ability to use geomagnetic data to study past climate patterns and understand how they might influence or be influenced by geomagnetic fluctuations, providing a clearer picture of the interplay between geomagnetic variations and climate.
The research also offered light on geomagnetic excursions, such as the Etruscan and Solovki, and their potential impact on climate.
By evaluating the timing and nature of these excursions, the study brought attention to the fact on how geomagnetic field fluctuations may correspond with periods of climate cooling and other key environmental occurrences.
“Today, scientists around the world are trying to predict when the next excursion will occur with all the ensuing climatic and man-made consequences,” Peskov stated, stressing geomagnetic studies’ broader implications for understanding historical climate dynamics and the role of geomagnetic changes in shaping regional and global climate patterns.
The study also brought into light the importance of peat sections as archives for paleomagnetic studies.
The Tyapka peat portion, in particular, contains a rich record of geomagnetic field shifts and climatic events, making it an ideal location for future research. While the work faced challenges in interpreting long-period harmonics and their climatic connections, it also opened up new options for further investigation of these linkages.
The conclusions of this study have important consequences for humans and life on Earth. Even minor geomagnetic excursions can disturb environmental and climatic conditions, having an impact on agriculture, ecosystems, and human health. With the north magnetic pole rapidly drifting, knowing geomagnetic behavior is important for anticipating future climate alterations and their consequences for society.
Geomagnetic excursions also endanger modern technology, particularly systems that rely on satellite navigation, power grids, and worldwide communications. As society becomes more electronically dependent, understanding and preparing for magnetic shifts becomes increasingly important.
Furthermore, the Earth’s magnetic field acts as a protective barrier against dangerous cosmic and solar radiation. During geomagnetic excursions, this protective barrier degrades, potentially increasing radiation exposure on Earth and affecting both technical systems and biological species.
References:
¹ Holocene Geomagnetic Excursions in Peat Deposits – Peskov, A.Y., Didenko, A.N., Karetnikov, A.S. et al. – Russ. J. of Pac. Geol. 18, 436–451 (2024) – August 9, 2024 – https://doi.org/10.1134/S1819714024700143
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