• by Erik Sass , Staff Writer @eriksass1, May 16, 2012

While GM may be disappointed with Facebook, plenty of other advertisers are still interested in social media, judging by the latest forecast from BIA/Kelsey, which predicts total social media advertising revenues will more than double over the next four years, jumping from $4.8 billion in 2012 to $9.8 billion this year. This includes both display advertising, which is predicted to grow from $4.6 billion to $9.2 billion, and non-display, on track to increase from $230 million to $630 million over the same period.

That represents a sizeable chunk of all online ad spending -- but not necessarily a big increase proportionally speaking. In a separate forecast, eMarketer sees total online ad spending growing from $32 billion this year to $62 billion in 2016. If both predictions turn out to be right, that means social media’s share will increase from 15% to 15.8% over the same period -- a marginal increase for what is supposed to be a hot new sector in a burgeoning medium (it’s worth noting that the eMarketer forecast is also lower than some others, with Forrester predicting $76.6 billion in overall ad spending by 2016).

Meanwhile, eMarketer predicts total U.S. ad spending will increase from $169.5 billion in 2012 to $196.7 billion in 2016. Thus online’s share of total ad spending will grow from 18.9% to 31.5% over this period, while social’s share of total ad spending will grow from 2.8% to 4.9%. In other words, despite its apparently impressive growth rate, according to these forecasts social media will not capture a larger share of online ad spending, and will be a fairly minor contributor to online’s proportional growth relative to other media; rather, it is just sort of “along for the ride.”

All this makes interesting reading following a fairly steep downward revision in growth projections for Facebook, which dominates social media ad spending: as noted in yesterday’s column, eMarketer recently revised its forecast for Facebook’s 2012 advertising revenues down from $6.1 billion to $5.06 billion -- a 17% reduction, suggesting advertisers may not be signing up for Facebook in quite the numbers you might expect based on all the buzz.