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Biggest solar superstorm yet, glimpsed in ancient tree rings

Solar superstorm: At left, the sun with big flares coming out, at right Earth and its magnetic field lines in blue.
View larger. | Artist’s concept of an active sun hurling a solar superstorm toward Earth (and its protective magnetosphere, shown in blue). New research has revealed the largest solar storm yet, from 14,300 years ago. If such a storm struck Earth today, it would be catastrophic for critical components of our global infrastructure. Image via NASA.

Biggest solar superstorm yet

Scientists said on October 9, 2023, that they have a new candidate for the biggest solar superstorm yet known. The evidence takes the form of radiocarbon (carbon 14) in ancient tree rings, which had been preserved in a riverbank in the French Alps. The scientists believe that, for this much radiocarbon to show up in tree rings, an immense spike in radiocarbon must have occurred in Earth’s upper atmosphere some 14,300 years ago. They believe the spike stemmed from a huge disturbance on the sun that rippled out across the solar system, a solar superstorm so powerful that we still see its effect, thousands of years later. Solar storms aren’t rare. But solar superstorms packing this much punch certainly are rare. If one were to strike Earth today, Earth’s atmosphere would protect our human bodies from harm. But the superstorm would likely cause billions of dollars in damages to human technologies, in particular to our electric grid, and also to satellites in Earth’s orbit.

The scientists said the solar superstorm was 10 times stronger than the solar storm that caused the famous Carrington Event – before now, considered the most intense geomagnetic storm in recorded history – which sparked fires at telegraph stations and spread auroras around the globe in the year 1859.

The international group of scientists is warning of the importance of understanding such storms to protect our global communications and energy infrastructure for the future.

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Tree rings tell the story

The peer-reviewed journal The Royal Society’s Philosophical Transactions of the Royal Society A published these researchers’ study on October 9.

The researchers analyzed preserved trees from along the banks of the Drouzet River in the French Alps. The trees were partially fossilized, and tiny slices of the tree rings showed an unprecedented spike in radiocarbon levels occurring precisely 14,300 years ago.

Cécile Miramont of Aix-en-Provence University said:

Finding such a collection of preserved trees was truly exceptional. By comparing the widths of the individual tree rings in the multiple tree trunks, we then carefully pieced together the separate trees to create a longer timeline using a method called dendrochronology.

This allowed us to discover invaluable information on past environmental changes and measure radiocarbon over an uncharted period of solar activity.

The role of radiocarbon

Edouard Bard, lead author of the study from the Collège de France and CEREGE, explained:

Radiocarbon is constantly being produced in the upper atmosphere through a chain of reactions initiated by cosmic rays. Recently, scientists have found that extreme solar events including solar flares and coronal mass ejections can also create short-term bursts of energetic particles that are preserved as huge spikes in radiocarbon production …

How did the radiocarbon make its way into the trees? The scientists’ paper explained:

The radiocarbon produced is not only circulated through the Earth’s atmosphere and oceans, but also absorbed by the biosphere and locked in the annual growth rings of trees.

The team compared this spike to the chemical beryllium from ice cores in Greenland.

A solar superstorm and Earth

If the solar storm from 14,300 years ago had struck Earth today, it might have wiped out human systems of telecommunications, satellites and electrical grids. These scientists expressed their belief in a need to protect human infrastructure from extreme behavior on our star, 93 million miles (150 million km) away. Tim Heaton of the University of Leeds said:

Extreme solar storms could have huge impacts on Earth. Such super storms could permanently damage the transformers in our electricity grids, resulting in huge and widespread blackouts lasting months.

Imagine if the satellite systems that bring you cell phone service or internet or GPS are suddenly gone, along with the electricity for warming and cooling your home or cooking and preserving food. Then you’ll understand why research into this area is so crucial. As Heaton said:

Radiocarbon provides a phenomenal way of studying Earth’s history and reconstructing critical events that it has experienced. A precise understanding of our past is essential if we want to accurately predict our future and mitigate potential risks. We still have much to learn.

What are Miyake Events?

Using tree ring and ice core data from the last 15,000 years, scientists have now identified nine huge solar superstorms. They call these solar superstorms Miyake Events for Japanese physicist Fusa Miyake, who was the first to identify the radiocarbon spikes. The two most recent Miyake Events were in 993 CE and 774 CE.

The 14,300-year-old Miyake Event is the largest scientists have yet found. It was about twice as strong as the events from 993 and 774 CE. Without direct observations of these events, it’s challenging to learn more about them. Scientists still don’t know what causes these powerful solar storms, how frequent they might be, and if we can predict them. Bard said:

Direct instrumental measurements of solar activity only began in the 17th century with the counting of sunspots. Nowadays, we also obtain detailed records using ground-based observatories, space probes, and satellites. However, all these short-term instrumental records are insufficient for a complete understanding of the sun. Radiocarbon measured in tree-rings, used alongside beryllium in polar ice cores, provide the best way to understand the sun’s behavior further back into the past.

The Carrington Event

And, by the way, the 1859 Carrington Event – which is well known in our time – wasn’t large enough to be considered a Miyake Event. We know about it because it occurred relatively recently, and the people who experienced it left behind their observations. As the scientists’ statement explained:

The largest, directly observed solar storm occurred in 1859 and is known as the Carrington Event. It caused massive disruption on Earth: destroying telegraph machines and creating a night-time aurora so bright that birds began to sing, believing the sun had begun to rise.

However, the Miyake Events (including the newly discovered 14,300-year-old storm) would have been a staggering entire order-of-magnitude greater [10 times greater] in size.

Bottom line: Researchers analyzing tree rings from the French Alps discovered the largest-known solar storm, which happened 14,300 years ago. If this storm hit today, it would wreck some critical human infrastructure.

Source: A radiocarbon spike at 14,300 cal yr BP in subfossil trees provides the impulse response function of the global carbon cycle during the Late Glacial

Via University of Leeds

Read more: How likely is another Carrington Event?

October 11, 2023
Human World

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