Why the undersea cables that connect the world are a subject of concern

The “backbone” of the internet, the data superhighway that connects the world’s online computer networks, is a web of fibre-optic cables. Between continents and land masses, the internet relies on cables crossing the sea floor.

This network, which is over half a million miles in length, and comprised of over 200 independent systems of interconnected cables, carries over 95% of global communications (the rest is carried by satellite). If you open a foreign webpage, the data you’re accessing will have been propelled by lasers down fibre-optic threads under the sea, at almost the speed of light. In a single day, this network also processes some $10trn in financial transfers via the SWIFT system, which manages global bank transactions.

The recent explosive growth of cloud computing has vastly increased the volume and sensitivity of data – from military documents to scientific research – crossing these cables.

How do the cables work?

Undersea cables have been used since the 1850s. Today, they’ve evolved into technological marvels. Laid by slow-moving ships, they are typically between two and seven inches thick and have a lifespan of approximately 25 years. Each cable contains fibre threads capable of transmitting data at 180,000 miles per second, wrapped in steel armour, insulation and a plastic coat.

These fibres have the capacity to transmit up to 400GB of data per second (about enough for 375 million phone calls); a single undersea cable contains anywhere up to 200 such fibres. By way of context, eight fibre-optic strands could transfer the entire contents of the Bodleian Library across the Atlantic in about 40 minutes.

Some new cables, such as the Asia-America Gateway cable, which links California to the Philippines and Southeast Asia, stretch to more than 10,000 miles in length.

Why are they a subject of concern?

Because of their vulnerability. To take an extreme recent example: in January, a volcanic eruption severed the single cable to Tonga, cutting off all communications to the Pacific island for five days. Phone contact has now been restored, via satellite, but normal internet service has still not been reinstated.

Damage occurs fairly regularly: an estimated 100 to 150 cables are severed every year, the vast majority due to fishing equipment or anchors. Usually, the system has enough slack in it to deal with such damage: most nations are connected by scores of fibre-optic cables, so if one or two are damaged, data can be rerouted without disruption. But problems do occur. In 2008, three cables linking Italy and Egypt were accidentally cut, causing data connectivity between Europe and the Middle East to plummet, with knock-on effects for American military operations in Iraq.

How could this affect the UK?

Britain, unlike Tonga, is connected to the rest of the world by around 60 cables, not just one: from the 80-mile CeltixConnect cable to Ireland; to the Tangerine, which runs 81 miles from Kent to Belgium; to the Tata TGN-Atlantic, stretching 8,000 miles from Somerset to New Jersey.

Article source: https://www.theweek.co.uk/news/technology/955812/undersea-cables-connect-world-subject-concern