These events were more powerful than the largest previously known outbreak, which occurred in 774 AD.
A team of scientists from nine countries examined the carbon-14 content of 8th and 6th millennium BC tree ring samples from Europe, Russia, and the United States and found that super-powerful solar flares occurred in 7176 and 5259 BC. Each of them led to the formation of approximately 29 additional kilograms of radioactive carbon in the Earth’s atmosphere.
Which are the most powerful solar flares in history?
Large solar flares occur quite regularly. Some of them can cause strong geomagnetic storms on our planet, contribute to the appearance of auroras at lower latitudes and disrupt satellites, as happened recently with 40 Starlink satellites.
Thus, the most powerful geomagnetic storm in the entire history of observations, recorded in 1859, led, in particular, to the failure of telegraph systems throughout North America and Europe, and the northern lights could be observed even at the latitude of Cuba.
Today, the consequences of such an event would be much more devastating: according to some estimates, the damage to US infrastructure would reach several trillion dollars.
In 2012, Japanese scientists discovered much more powerful solar flares that occurred during the early Middle Ages. Using accelerator mass spectrometry, they studied cedar tree rings, which had previously been dated using dendrochronology.
The tree rings revealed that in 774 and 993 there were super-powerful solar flares, which led to multiple increases in the amount of radiocarbon in the Earth’s atmosphere. Later, another surge was recorded in 660 BC.
Scientists found evidence of extreme solar flares in ancient tree rings
Lukas Wacker of the ETH Zurich, together with an international team of scientists, investigated the content of carbon-14 in the growth rings of ancient trees. The scientists focused on dendrochronologically dated wood samples that covered two time periods: 7200–7150 BC and the middle of the 13th century BC.
These periods are related to the fact that in the first case, glaciologists discovered the anomalous content of beryllium-10 and chlorine-36 in ice columns, and in the second case, with conflicting dating of archaeological materials of that time.
For analysis by accelerator mass spectrometry, scientists selected samples of larch, oak, spiny pine, which were found in the Alpine region, Ireland, Russia, and the United States. As a result of the study, they found in materials from different regions that two super-powerful solar flares occurred in 7176 and 5259 BC.
In the first case, this led to an additional formation of 28.7 ± 0.9 kilograms of radioactive carbon in the Earth’s atmosphere, and in the second, 29.2 ± 0.9 kilograms. This exceeds the power of the outbreak that occurred in 774 when an additional 26.2 ± 1 kilogram of carbon-14 was formed.
Scientists noted that the growing number of discoveries of super-powerful solar flares that had an impact on the Earth in the Holocene epoch, that is, over the past about 12 thousand years, no longer allows them to be considered extremely rare events.
An analysis of data from tree rings spanning a total of 2030 years of sequences shows that super-powerful solar flares hit the Earth every 400–2400 years. The researchers concluded that such events if they happened today, would have a catastrophic impact on aviation, satellites, and telecommunications systems.
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• Brehm, N., Christl, M., Knowles, T. D. J., Casanova, E., Evershed, R. P., Adolphi, F., Muscheler, R., Synal, H.-A., Mekhaldi, F., Paleari, C. I., Leuschner, H.-H., Bayliss, A., Nicolussi, K., Pichler, T., Schlüchter, C., Pearson, C. L., Salzer, M. W., Fonti, P., Nievergelt, D., … Wacker, L. (2022, March 7). Tree-rings reveal two strong solar proton events in 7176 and 5259 BCE. Nature News.
• Fitzgerald, R. (2022, March 4). Tree rings offer glimpse 600 years into the past. they spell a drier time and troubling future for the NT. ABC News.
• MSN. (n.d.). Mega explosion from sun captured in tree ring from almost 10,000 years ago.