image: Stalagmites in southern China preserve detailed geomagnetic oscillations and centennial geomagnetic reversal events. view more
Credit: PNAS
A study suggests that oscillations in geomagnetic field polarity can occur on timescales as short as one to two centuries. Reversals of geomagnetic polarity over time have been found in various rock types, and cave formation limestone features have proven useful in reconstructing paleomagnetic records. Previous studies have recorded a decrease of around 10% in Earth's magnetic field strength in the last century, suggesting a possible future field reversal. Chuan-Chou Shen, Yu-Min Chou, and colleagues used a stalagmite from Sanxing Cave in southwestern China to construct a paleomagnetic record from 107,000 to 91,000 years ago at multidecadal resolution. The authors found oscillations in the geomagnetic field on both millennial and centennial scales, with one reversal occurring over approximately 144 years, a rapid transition. The authors report that the number and duration of geomagnetic oscillations recorded may indicate a prolonged period of geodynamo instability. According to the authors, the stalagmite provides a high-resolution magnetic record suggesting that geomagnetic changes can occur more rapidly than previously thought.
Article #17-20404: "Multidecadally resolved polarity oscillations during a geomagnetic excursion," by Yu-Min Chou et al.
MEDIA CONTACT: Chuan-Chou Shen, National Taiwan University, Taipei, TAIWAN; e-mail: river@ntu.edu.tw; Andrew P. Roberts, Australian National University, Canberra, AUSTRALIA; tel: 61-2-61251420, 61-4-34668243; e-mail: andrew.roberts@anu.edu.au
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