ZenithOptimedia, part of Publicis Groupe, estimated that adspend levels would rise by 3.3% at current prices in 2012 to $497bn, and by 4.1% in 2013, to $518bn. The growth figure for 2013, however, was cut by half a percentage point since its previous forecast issued in October 2012.
Looking further ahead, the organisation suggested that the entire industry should expand by 5% to $543bn in 2014, and then register an additional 5.6% gain to $574bn in 2015.
Total North American returns are due to increase from $172bn this year to $194bn by the close of the forecast period. Within this, these totals stood at $161bn and $182bn for the United States.
Asia Pacific is projected to witness an improvement from $140bn to $167bn, with China supplying $12.5bn of regional growth, and Indonesia another $4.5bn. Japan will also deliver an extra $2.5bn.
Latin America's ad sector will add nearly $12bn to its net worth by 2015, when it will total $49.8bn. Brazil alone will yield $5.6bn of growth, more than the $4.7bn expansion slated for Western Europe as a whole in the next three years, which is forecast to reach $112bn in 2015.
By medium, television was pegged to see revenues jump from $198bn in 2012 to $226bn in 2015. Its share of spending is set to remain steady over this period, at just over 40% of all media spend.
Elsewhere, the web will boost its proportion of ad sales from 18% to 19.8% in the same timeframe, equating to returns of $88.6bn and $101bn this year and next respectively. By 2015, online will account for 23.4% of the market, and take $132bn.
Newspapers are anticipated to accrue $90.1bn, or 15.9%, of revenues in 2015, off from $93.1bn in 2012, an 18.9% share. Magazines will also endure a dip of 1.5 percentage points on this measure, as sales slide from $43.2bn to $41.6bn.
"Advertisers are willing to increase their budgets wherever they can achieve a strong return on investment," Steve King, ZenithOptimedia's global CEO, said. "This means that developing markets, social media and online video are all growing rapidly."
Separately, GroupM, part of WPP Group, predicted adspend would rise by 4.5% to $531bn in 2013, a downgrade from the 5.3% increase the firm outlined in June this year.
Data sourced from ZenithOptimedia/GroupM; additional content by Warc staff