World's stored data approaches 300 exabytes

A study at the University of Southern California has estimated that the world's data storage stood at 295 exabytes (295 billion gigabytes) in 2007.

The researchers compiled estimates of the data stored in 60 analogue and digital formats, ranging from paper and books through to servers and data held on credit cards or X-rays. They estimated that between 1986 and 2007 the world's data storage capacity was 295 exabytes.

"If we were to take all that information and store it in books, we could cover the entire area of the US or China in three layers of books," Martin Hilbert, of the University of Southern California, told the BBC's Science in Action programme.

The researchers noted that there had been a revolution in the switch from analogue to digital storage of data. Three-quarters of all human data was in analogue format in 2000, but just seven years later digitally stored data made up 94 per cent of the total.

"There have been other revolutions before. The car changed society completely, as did electricity. Every 40, 50 or 60 years something grows faster than anything else, and right now it's information," said Hilbert.

"Basically what you can do with information is transmit it through space, and we call that communication. You can transmit it through time, and we call that storage. Or you can transform it, manipulate it and change the meaning of it, and we call that computation."

Global computing power rose by 58 per cent annually over the period of the study, but there is a growing information gap.

In 2002 people in the developed world could communicate eight times as much data to others as those in the developing world, but this had risen to 15 times by 2007.