A new report shows that online, mobile and digital advertising will spur global ad growth through the remainder of 2015 and into 2016. The report, from Zenith Optimedia (a subsidiary of ad agency Publicis), says surging growth in advertising via mobile phones and tablets will help online marketing spending overtake television as the dominant ad medium by 2017.

Zenith Optimedia said it expects mobile advertising to more than double its share of global ad spending between 2014 and 2017, to 12.9%. It would contribute 70% of the growth in all advertising spending over that period.

"The Internet is quickly establishing itself as the dominant advertising medium, and on current trends will overtake television by the end of the decade," said Steve King, CEO of Zenith Optimedia. "The amount of time viewers spend watching online video on their laptops, tablets and smartphones is increasing rapidly, and advertisers are shifting their budgets online to follow them.”

Across all media in the U.S., Zenith Optimedia forecasts that ad spending will rise by 3.7% in 2015, 4% in 2016 and 3.7% to $197.2 billion in 2017. “Our largest increase in spend for 2015 are all from the digital category,” Zenith Optimedia said, noting a 32% increase in spending on social media and 26% growth for online video.

“The growth of digital video viewers continues to rapidly increase due to growing content, user acceptance and consumers’ higher comfort level of watching video through multiple platforms,” Zenith Optimedia said in its report. “With growing digital video consumption, video ad spending is also up across all devices, with mobile devices seeing especially large growth.”