The stunning aurora borealis in early May demonstrated the power that solar storms can unleash, but sometimes these solar activities have even more devastating effects.
A new study has warned that a powerful explosion that occurs roughly every thousand years from the surface of the sun could severely disrupt the Earth's ozone layer and affect all life on Earth.
These explosions of protons directly from the Sun's surface are known as "solar particle events," and can shoot out like a searchlight into space.
Scientists say this intense "solar particle event" could expose people to high levels of harmful ultraviolet radiation, causing higher cancer rates and even leading to changes in global climate.
The study, published in the journal PNAS, assessed what could happen on Earth during such an extreme event, especially at times when the planet's protective magnetic shield is weakest.
Normally, Earth's magnetic field protects the planet by deflecting charged particles into space, but the strength of this magnetic shield can vary.
At the same time, the Sun's surface also releases highly energetic protons, "solar particle events," which can reach low altitudes in Earth's atmosphere.
But about every millennium, there may be extreme solar particle events "thousands of times more powerful than anything recorded with modern instruments."
While contemporary solar particle events are weak and easily deflected by Earth's magnetic field, extreme events have occurred in the past.
Scientists warn that such an extreme event could tip over a series of dominoes in the Earth's ozone layer and disrupt it for more than a year.
“Very high UV-B intensity can inhibit plant growth and photosynthesis and generate high levels of DNA damage in many species,” the scientists wrote.
In humans, this may lead to an increased risk of skin cancer, cataracts, and impaired immune function with symptoms of eye damage appearing as early as 30 minutes to 12 hours after UV exposure.
If such a blast from the Sun reached Earth during a period when the planet's magnetic field was much weaker, the damage to the ozone layer could last for about six years.
This could increase the levels of UV radiation reaching the Earth by 25% and damage DNA by up to 50%, which could be catastrophic for crops grown around the world.
“The resulting ground-level UV radiation will remain elevated for up to 6 years, resulting in increases in the UV index of up to 20 to 25% and rates of solar-induced DNA damage of 40 to 50%,” the scientists wrote.
Widespread DNA damage may also trigger periods of evolution, such as the rapid diversification of animals during the Cambrian explosion about 539 million years ago.
“During these periods, ionizing cosmic particles can enter Earth’s atmosphere at low latitudes and damage the ozone layer, leading to significant increases in surface ultraviolet radiation,” the scientists continued. “Potential consequences include serious health risks and long-term climate and evolutionary impacts.”
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