Undersea internet cables may be susceptible to damage from solar storms for a number of reasons. To route data intact across oceans, cables are fitted with repeaters at intervals of about 50 to 150 kilometers, depending on the cable. These devices amplify the optical signal and ensure that nothing is lost during transport, such as a relay throw in baseball. While fiber optic cable isn’t directly vulnerable to disruption from geomagnetically induced currents, the electronic insides of repeaters are — and enough repeater failures will render an entire submarine cable useless. In addition, submarine cables are only grounded at longer intervals, hundreds or thousands of miles apart, leaving vulnerable components like repeaters more exposed to geomagnetically induced currents. The composition of the seafloor also varies, so some grounding points may be more effective than others.
In addition, a major solar storm could also disable any equipment orbiting Earth and enable services such as satellite internet and global positioning.
“There are currently no models available of how this might turn out,” says Abdu Jyothi. “We have a better understanding of how these storms would affect energy systems, but that’s all on land. In the ocean, it’s even harder to predict.”
Coronal mass ejections tend to have more impact at higher latitudes, closer to Earth’s magnetic poles. Therefore, Abdu Jyothi is more concerned about cables in some regions than in others. For example, she found that Asia is less at risk, because Singapore acts as a hub for many submarine cables in the region and is located on the equator. Many cables in that region are also shorter, as they branch in many directions from that hub rather than being arranged as one continuous span. Cables crossing the Atlantic and Pacific Oceans at high latitudes are at greater risk in even moderate storms.
The global internet is built for resilience. If one path is unavailable, traffic will be rerouted through other paths, a feature that may maintain connectivity even at slower speeds in the event of a solar storm. But enough damage to these vital arteries would begin to destabilize the network. And depending on where the cable outages occur, Abdu Jyothi says fundamental data routing systems such as the Border Gateway Protocol and Domain Name System could fail, causing a knock-on outage. It’s the internet version of the traffic jams that would result if road signs disappeared and traffic lights went out at busy intersections in a major city.
North America and some other regions have minimum standards and procedures for grid operators regarding solar storm preparedness. And Thomas Overbye, director of the Smart Grid Center at Texas A&M University, says grid operators have made some progress in reducing risk over the past 10 years. But he emphasizes that since geomagnetic disturbances are so rare and relatively unstudied, other threats, such as extreme weather events or cyber-attacks, are increasingly prioritized.
“Part of the problem is we just don’t have much experience with the storms,” Overbye says. “Some people think a geomagnetic disturbance would be a catastrophic scenario and there are others who think it would be a minor event. I’m a bit in the middle. I think it’s something that we as an industry definitely want to be prepared for and I’ve been working on developing tools that assess risk. But there are also many other things in the industry that are important.”