Some $100bn will be slurped up by public IT cloud services by 2016, according to the crystal-ball gazers at IDC.

Spending is set to peak at $40bn this year but is forecast to expand more than 26 per cent on a compound annual growth basis over the next four years – five times faster than the total industry average.

"The IT industry is in the midst of an important transformative period as companies invest in the technologies that will drive growth and innovation over the next two to three decades," said IDC chief beancounter Frank Gens.

He added that by the close of this decade, at least 80 per cent of industry growth as well as enterprises' "highest value leverage of IT" will pertain to cloud services and other third-platform tech.

The public cloud specifically is predicted to account for 16 per cent of global IT revenues in five categories: applications, Software-as-a-Service (SaaS), platform-as-a-service, servers and basic storage.

SaaS – both apps-as-a-service and system infrastructure software-as-a-service as a service – is expected to be the largest public cloud segment, but growth in the other four areas will be the fastest.

IDC reckons cloud services will generate 41 per cent of all growth in the five segments by the end of the forecast period in 2016. "Quite simply, vendor failure in cloud services will mean stagnation," said Gens.

This means the rate of cloud provision from the channel must keep pace with the industry average if solution providers want to remain relevant to customers – at least if any credence is given to IDC's research.

The US is expected to remain the highest spender on public clouds, followed by Western Europe and Asia Pacific, though growth in emerging markets will be the swiftest; these regions are forecast to account for nearly 30 per cent of new public cloud services by 2016. ®