50% of Google paid search clicks will come from mobile devices by December of next year, according to Marin Software, which has a new report out on the subject. That figure is based on the current growth rate.

The report (via Search Engine Land) is based on data from advertisers who invest over $6 billion per year in ad spend on Marin’s platform. It also found that cost per click on mobile device s increased at a much higher rate that on desktop last year, with tablet CPCs surpassing desktop in some regions.

Conversion rates on tablets and smartphones increased throughout last year as users got more comfortable with mobile commerce, the report says. Conversion rates on tablets even surpassed those on desktops.

Marin CMO Matt Ackley says, “We’re at the cusp of mobile becoming the dominant channel in search marketing. Consumers are becoming much more comfortable using their smartphones and tablets to complete transactions online, and as we see that comfort level rise advertisers will follow suit with continued investment and optimization in mobile.”

A new report from eMarketer finds that global mobile ad spend increased by 105% in 2013, reaching $17.96 billion, and is on pace to hit $31.45 billion this year.

Images via Marin Software