Internet demand could outpace capacity within the next two to four years, causing global slowdowns and 'brownouts', according to a new report.

Nemertes Research reckons that 2012 could be a crunch year for the web, as the exaflood - an exponential explosion of online content resulting from new applications and video - causes slower responses and time outs, ultimately triggering an 'innovation slowdown'.

If left unaddressed, say Nemertes, the development of next generation applications will be stifled as users find Internet infrastructure incapable of delivering content.

Americans take more than their share of the web

"We project demand to exceed capacity at the access layer of the Internet by 2012, and the situation is slightly worse in North America," says Dr Mike Jude, Senior Analyst at Nemertes.

He estimates the financial investment required to bridge the gap between demand and capacity is about £91 billion worldwide.

The report comes on the same day that the total number of broadband subscribers worldwide topped 400 million for the first time - that's 7000 times the number of broadband connections that existed a decade ago.

Next-gen ultra-high-speed optical fibre connections currently account for about 45 million of those users.