Would the global internet come to a standstill if undersea cables were severed?

There is currently significant discussion about whether satellites in space could keep the world connected if undersea internet cables were cut. Could Elon Musk’s ‘Starlink’ keep the world online? The simple answer is that while Starlink could help maintain essential communications during a crisis, it lacks the capacity to serve as a replacement for the vast network of undersea cables.

Approximately 99 percent of international data exchange takes place via fiber-optic cables laid on the ocean floor. This global network, spanning about 1.7 million kilometers, experiences around 200 incidents annually due to various causes. The severing of even a single cable can leave millions of people without internet access and cause major disruptions to a nation’s international data flow.

The disparity in capacity between cables and satellites can be illustrated through simple arithmetic. While a typical undersea cable can transmit 20 terabits (20,000 gigabits) of data per second, a single backup satellite might only handle 1 gigabit. In terms of data transmission capacity, a cable is roughly 20,000 times more powerful than a satellite. Consequently, to match the throughput of just one cable, thousands of satellite links would need to operate simultaneously—a scenario that is not practically feasible.

Repairing damaged undersea cables can take anywhere from several days to several weeks. During such critical periods, Starlink and other satellite systems serve as a secondary safety net. This technology helps sustain vital functions—such as hospital operations, government emergency services, limited financial transactions, and basic messaging—during disasters. However, it is impossible for satellite systems to support the entire population streaming high-quality video, transferring large data files, or meeting the constant, high-volume data demands of major business enterprises. According to experts, relying solely on satellites is not enough to keep the internet system fully secure. Only through a combination of three technologies—undersea cables, terrestrial fiber-optic networks, and space-based satellites—can we avoid a major digital catastrophe and keep the entire world connected.

Source: Gulf News