Internet advertising will overtake television advertising globally in 2017, ZenithOptimedia forecasts.

In a new Advertising Expenditure Forecasts report, the media agency singles out internet ads as the main driver of global adspend growth.

Spending on online ads is set to grow at over three times the global average rate this year (15.7%).

Sustained growth, along with downgrades to television in Brazil and China, will be behind it leapfrogging TV in 2017, a year earlier than ZenithOptimedia predicted back in December.

When it comes to the global ad market, growth of 4.6% is expected for this year, up 3.9% on 2015.

Global advertising expenditure will total $579 billion in 2016, and exceed $600 billion in 2017.

Advertisers' confidence has not been overly affected by the problems facing the world economy, thanks to upcoming special events in 2016 (the Euros, Olympics and more), the rapid recovery of markets worst hit by the Eurozone crisis, and the emergence of rapidly growing markets.

Ireland in particular has bounced back strongly.

Adspend in Ireland had fallen by a total of 45% between 2007 and 2013.

It then recovered by 8.9% in 2014 and 7.3% in 2015, with ZenithOptimedia forecasting average Irish growth of 6.7% a year to 2018.