LONDON: Traditional TV viewing around the world is expected to peak this year and then begin to decline for the first time in 2016, according to a new report.

Based on analysis of 40 key markets, media services network ZenithOptimedia forecast that the number of global linear TV viewers will rise 3.1% in 2015, but then fall by 1.9% in 2016 and 0.9% in 2017.

At the same time, online video viewing is expected to record strong growth of 23.3% this year, rising to 19.8% in 2016, on the back of rapid adoption of mobile devices across the globe.

Video consumption on mobile devices is forecast to grow by 43.9% in 2015 and 34.8% in 2016, putting mobile on course to become the main platform for viewing online video next year.

Mobile is expected to account for 52.7% of all online video viewing in 2016, rising to 58.1% in 2017, and advertising expenditure will follow the development.

Adspend dedicated to online video is expected to increase to 12.8% by 2017, or an eighth of all internet adspend, as budgets for the platform grow steadily over the next two years.

Global online video adspend is forecast to grow 28.9% to $16.1bn in 2015 followed by 22.5% growth in 2016. It is then expected to grow another 19.7% in 2017, taking the total to $23.7bn.

The research was carried out in partnership with Newcast, ZenithOptimedia's global branded content network.

Commenting on the report, Mark Waugh, global managing director at Newcast, observed that consumers around the world are rapidly embracing online video because it offers them "a near limitless array of engrossing content".

"Some of the keenest users are the young, affluent viewers who are hardest to reach on television," he said.

"Brands are finding online video a particularly effective way to reach these valuable audiences, not just with advertising, but also with branded content," he added.

He said branded content on video is able to inform and entertain consumers in "a deeper and richer way than is possible with short, interruptive ads".

Data sourced from ZenithOptimedia; additional content by Warc staff