• by Laurie Sullivan , Staff Writer @lauriesullivan, August 28, 2013

Marketers have finally caught up to the increase in use of mobile search by consumers. Not tablets, but rather smartphones. Google and Facebook will grab most of the mobile market share.

In fact, eMarketer estimates that Google will support 53.17% of the worldwide mobile ad market in 2013 -- up from 52.36% in 2012, and 38.11% in 2011. The research company attributes this to growth in mobile and use of YouTube.

Facebook's No. 2 position with 15.80% worldwide market share shows gains in social media, while the Internet music service Pandora will take 2.37% worldwide market share -- a slow decline from 2.71% last year and 2.99% in 2011.

Pandora is an interesting example of a company declining in market share and revenue, but increasing in earnings and listeners. Its 71.2 million users listened to about 3.88 billion hours of music last in Q2 2013, up 18% year-over-year.

Overall, eMarketer estimates that the mobile ad market worldwide should grow 89% to $16.65 billion in 2013.

Mobile search advertising will contribute more than 22% to $4.3 billion to overall mobile ad sales in the U.S., according to eMarketer.

Across all devices, Google remains the No. 1 digital ad publisher worldwide this year, taking nearly 33% of all digital ad dollars -- up from 31.46% in the prior year, according to eMarketer. Facebook will also increase its share of the total, to 5.41%, while Yahoo will decline some. Microsoft's share of the worldwide market will hold steady.

In June, eMarketer forecast that Microsoft would generate a tad more than $2.08 billion in worldwide ad revenue, but recently revised that estimate to $2.92 billion.