Digital advertising, particularly mobile, is enjoying a growth spurt as search remains the biggest driver of ROI for marketers, new research has shown.

According to Adobe’s latest Global Digital Advertising Update, search spend has increased 16% year-over-year in the US and 3% in the UK during Q1 2012. Industry sectors such as finance and automotive showed large increases in spend whilst the retail sector dropped 5%, said the report.

As traffic on mobile devices and tablets continues to grow four-fold year-on-year, so is spend on mobile search, according to the figures. In Q1, mobile spend claimed 8% of all search spend in the US and 11% in the UK. Of this, tablets alone accounted for 4.25% of search spend, the figures showed.

Looking ahead, tablets and mobile devices will continue to assume a larger percentage of overall search spend, reaching 15 to 20% by the end of this year, predicted Adobe. According to the firm, marketers should focus on tablet and mobile markets as they still appear to be underinvested opportunities.

Additionally, Adobe predicted that based on current trends, tablets may “cannibalise” smartphone and desktop search spend as investments continue to shift to tablet devices.

To view the full report, click here.