Nearly all intercontinental traffic is on the seabed
The large majority of data between continents travels on submarine cables, not by satellite. A modern cable is about as thick as a garden hose.
Satellites matter for remote places, for ships, and for broadcast. They do not carry the bulk of the traffic between Europe and America, or America and Asia. That traffic is light in glass, under a few centimetres of plastic, steel, and tar, laid on or under the sediment. The first transatlantic fibre cable, TAT-8, went into service in 1988. The capacity since then has gone up by factors that make the original cable a curiosity. The geography has not changed. The shortest reliable path is still the ocean floor.
Anchors, trawls, and earthquakes break these cables, and a break is a ship, weeks, and a splice. The network is redundant because the physical thing is fragile and slow to mend. When a region goes dark after a quake offshore, the cause is often a hose.
Caveats
- Estimates of the share — often put well above nine tenths of intercontinental capacity — move as satellite constellations grow. They have not, so far, moved the bulk.
- Within a city, and within a continent, the traffic is on land. The claim is about the long crossings.
Sources
- 1Carter L. et al.. Submarine Cables and the Oceans. UNEP-WCMC, 2009.