Undersea internet cables are potentially susceptible to solar storm damage for a few reasons. To shepherd data across oceans intact, cables are fitted with repeaters at intervals of roughly 50 to 150 kilometers depending on the cable. These devices amplify the optical signal, making sure that nothing gets lost in transit, like a relay throw in baseball. While fiber optic cable is not directly vulnerable to disruption by geomagnetically induced currents, the electronic internals of repeaters are — and enough repeater failures will render an entire undersea cable inoperable. Additionally, undersea cables are only grounded at extended intervals hundreds or thousands of kilometers apart, which leaves vulnerable components like repeaters more exposed to geomagnetically induced currents. The composition of the sea floor also varies, possibly making some grounding points more effective than others.
On top of all of this, a major solar storm could also knock out any equipment that orbits the Earth that enables services like satellite internet and global positioning.
“There are no models currently available of how this could play out,” Abdu Jyothi says. “We have more understanding of how these storms would impact power systems, but that’s all on land. In the ocean it’s even more difficult to predict. “
Coronal mass ejections tend to have more impact at higher latitudes, closer to the Earth’s magnetic poles. That’s why Abdu Jyothi worries more about cables in some regions than others. She found, for example, that Asia faces less risk, because Singapore acts as a hub for many undersea cables in the region and is at the equator. Many cables in that region are also shorter, because they branch in many directions from that hub rather than being set up as one continuous span. Cables that cross the Atlantic and Pacific oceans at high latitude would be at greater risk from even moderate storms.
The global internet is built for resilience. If one pathway is not available, traffic reroutes across other paths, a property that could potentially keep connectivity up, even at reduced speeds, in the event of a solar storm. But enough damage to these vital arteries would start to destabilize the network. And depending on where the cable outages occur, Abdu Jyothi says that foundational data routing systems like the Border Gateway Protocol and Domain Name System could start to malfunction, creating knock-on outages. It’s the internet version of the traffic jams that would happen if road signs disappeared and traffic lights went out at busy intersections across a major city.
North America and some other regions have minimum standards and procedures for grid operators related to solar storm preparedness. And Thomas Overbye, director of the Smart Grid Center at Texas A&M University, says grid operators have made some progress mitigating the risk over the past 10 years. But he emphasizes that since geomagnetic disturbances are so rare and relatively unstudied, other threats from things like extreme weather events or cyberattacks are increasingly taking priority.
“Part of the problem is we just do not have a lot of experience with the storms,” Overbye says. “There are some people who think a geomagnetic disturbance would be a catastrophic scenario and there are others who think it would be less of a major event. I’m kind of in the middle. I think it’s something that we certainly as an industry want to be prepared for and I’ve been working to develop tools that assess risk. But yet there are a lot of other things going on in the industry that are important, too. ”