With publishers serving more and more of their audience through mobile and tablet devices, it’s no surprise that responsive designs are growing in popularity.

From the BBC and Guardian to Metro and Express & Star, the number of publishers jumping on the responsive design bandwagon is growing rapidly and for good reason: there’s a lot to like about responsive design and done right, it’s pretty compelling.

Now, one of the biggest names in digital publishing in the U.S., AOL, is getting behind responsive design, and in a big way.

According to AdAge, AOL is planning to redesign all of its content destinations in an effort to bolster the company’s ad sales and serving process.

At CES, AOL’s president of technology and entertainment, Jay Kirsch, explained that the company’s responsive redesigns for Engadget and Games.com have given the company the opportunity to serve up mobile-friendly ads that appear while users scroll, disappearing after a short period. The benefit: CTRs three times higher.

The new normal?

AOL’s plans reflect a fundamental shift in the digital publishing landscape. The desktop, while still important, isn’t the only game in town and with high levels of mobile and tablet usage here to stay, publishers must figure out how to serve an audience in ways that scale across devices with varying screen sizes.

Responsive design, of course, isn’t the only option. Publishers may still have reason to look at native apps and separate mobile sites. But from a user experience perspective, having a single site that adapts to the user’s device makes a lot of sense.

For publishers looking to develop and execute on mobile and tablet publishing strategies, the big question is if and when to make the investment. One would have to assume that AOL’s responsive design initiative isn’t cheap — and it certainly isn’t without risk — but one must also assume that publishers wanting to succeed in this brave new world can’t do nothing forever.