In 1859, Earth experienced a powerful solar flare known as the Carrington event, which bathed the world in colorful aurorae and wreaked havoc on telegraph systems. Despite being widely witnessed, there was no physical evidence of the event until recently when ecologist Joonas Uusitalo and his team discovered atoms of carbon-14 preserved in tree rings in Finland’s far north, marking the first known traces of the Carrington event in tree rings. Previous tree rings have recorded more powerful solar flares from before modern record-keeping, such as those in 774 and 993.
The polar trees in Finland’s Lapland region were found to be more sensitive to solar storms compared to trees in mid-latitudes, leading to a significant increase in carbon-14 during the Carrington event. The additional sensitivity of polar trees may be due to how solar particles interact with Earth’s magnetic field, creating disturbances that produce aurorae and affect radio signals. Solar flares emit particles that react with the atmosphere to produce carbon-14, which then makes its way into the tissue of living trees, preserving a record.
These carbon-14 spikes in tree rings, called Miyake events, have been linked to solar storms, providing a new insight into the detection of moderate-sized solar storms using polar tree rings. The fast air exchange between the stratosphere and troposphere in the Arctic contributes to the accumulation of carbon-14 in polar trees, making them suitable sensors for weaker storms. Scientists plan to further investigate other historical solar storm events using tree rings closer to the North Pole.
The discovery of carbon-14 spikes in polar tree rings could enhance scientists’ understanding of radiocarbon records and the link between Miyake events and solar storms. This finding offers new support for the association between the two but needs further replication with other high-latitude tree rings for confirmation. Studying tree rings over longer periods can reveal more about the sun’s activity and its impact on carbon-14 production, offering insights into historical solar cyclicity and atmospheric circulation patterns.
It is essential to continue studying high-latitude trees to uncover more secrets about Earth’s history and the sun, as these trees may provide critical information about solar activities and their effects on the planet. Analyzing more trees closer to the poles could offer valuable data on historical solar events and their impact on Earth’s environment, providing a deeper understanding of the relationship between the sun and our planet’s climate. Future studies may unveil new insights into the historical and cyclical patterns of solar activity through the examination of tree rings in polar regions.
