Our sun is currently in an active phase which is seeing an increased number of solar storms. During such events, particles from the sun can, in the worst case, cause serious damage to modern infrastructure. Power lines, navigation systems, satellites and other equipment can be damaged.
At Geocentrum in Lund, world-leading research is underway in the hunt for a better understanding of solar flares. So, we leave a pleasant day on Sölvesgatan behind us as we step through a heavy door and are greeted by a biting chill. Beyond the door is a freezer room filled with large volumes of ice from both Greenland and Antarctica.
An archive of millennia-old ice
In here, the cooling fan whirs noisily to maintain a temperature of minus 18 degrees. Valuable research material stored in the polystyrene boxes bears witness to historical solar storms. Professor of Geology Raimund Muscheler lifts the lid to reveal the long, thin, plastic-wrapped samples.
“We have Greenlandic ice from the past 10,000 years, but we also have ice that is several hundred thousand years old, from Antarctica,” he says.
The archive of frozen water molecules contains clues that will help researchers to chart all the major solar storms of the past 10,000 years, and hopefully medium-sized storms as well. The ice samples provide a sufficiently sufficient detail to enable the measurement of each individual year throughout the entire period.
“This has never been studied systematically, in such detail before,” says Raimund Muscheler.
Ten centimetres equals a year
A year on our planet is equivalent to a depth of around ten centimetres in the Greenlandic ice. The long, thin samples in the polystyrene boxes in front of us are simply snow that fell many winters ago. In other words, here we have snow from the Viking era, from the age of the Roman Empire, and from the time when our Stone Age ancestors were exploring the planet.
We leave the sub-zero temperatures behind and move to a nearby lab space in the same corridor. Here, Raimund Muscheler has thousands of thawed samples from the Greenlandic ice sheet. In the lab, the samples are prepared so that the radioactive isotopes that reveal which years saw powerful solar storms can be analysed.
All of the samples, frozen and thawed, come from a long-term international collaboration on an ice drill that has patiently worked its way through the 2,500-metre-thick Greenland ice sheet. Raimund Muscheler’s new research project focuses on the uppermost 1,200 metres of the sheet, which roughly equates to the last 10,000 years.
ERC grant to fund the research
Earlier this year, Muscheler received a substantial and prestigious research grant from the European Research Council, ERC, for this research. His project focuses on how often solar storms occur and the link between solar storms and what is known as the sunspot cycle.
The more sunspots, the more solar flares. Each such cycle lasts an average of eleven years. This begins with a period of fewer sunspots, a sunspot nadir, before the number of sunspots increases and reaches a peak, after which activity declines again towards the end of the cycle. The current cycle began in 2019 and is expected to last until 2030.
Muscheler wants to investigate whether there is a historical pattern when it comes to extremely large solar storms. Thus far, the research has discovered five such enormous solar proton flares over the past 10,000 years – they are thought to have been at least ten times more powerful than the largest seen in the recent past.
“Such powerful solar storms could have devastating consequences for contemporary society,” says Raimund Muscheler.
The oldest of these solar superstorms took place 9,200 years ago. The next oldest occurred 7,210 and 2,610 years ago respectively. The two more recent storms were dated 774 and 993 AD. A couple of these solar superstorms did not follow the general pattern for sunspot cycles. Interestingly enough, they probably occurred during reduced solar activity, instead of at the sunspot peak,” explains Raimund Muscheler.
A risk to be taken more seriously
One challenge facing the research project is that the ice samples only reveal the sun’s proton flares, but they cannot show whether those flares also caused a geomagnetic storm on Earth. A range of different factors determine whether a solar storm that hits our planet also affects the Earth’s magnetic field and therefore results in a geomagnetic storm.
Raimund Muscheler explains, however, that if our modern society were to be struck by a solar superstorm and a resulting geomagnetic storm, we can count on the effects being far more powerful than anything we have ever experienced in modern times. He hopes that the research will enable better risk assessments around these issues.
“How do we deal with the electricity supply being completely knocked out for weeks or even months? I don’t think we are taking this risk seriously enough,” he says.
