Marketing executives face a world that is radically different from it was just a decade ago, according to participants in a breakfast roundtable at Fortune’s Brainstorm Tech conference in Aspen, Colo. on Tuesday.

While the discussion was spirited and varied, four major forces emerged from the discussion as driving today’s marketing business:

Complexity. Steve Lucas, CEO of Marketo, said “the number one challenge facing marketing today is complexity.” He said the company’s clients are overwhelmed by the myriad of choices they now have for reaching clients. “It’s not a lack of choice, it’s an abundance of choice.”

Speed of change. J.D. Osborne, the CEO of Red Antler, said in the first five years of his business, “we would see trends play out over a year.” Now, “that’s condensed over a period of a couple of weeks or a month.”

Artificial intelligence. Much of the breakfast discussion focused on how to find useful signals in the flood of data that companies now face. Lucas said that will drive the business to rely ever more on artificial intelligence, which is something most marketers don’t understand. “The biggest challenge, after complexity, is AI,” said Lucas. For marketers, “it wasn’t a class when they were in school.”

Marketing doesn’t end with a purchase. In a social media world, the CMO’s job is not just to drive purchases, but to create brand enthusiasts. “The marketer is being forced to take ownership of the customer experience,” said Ragy Thomas, CEO of Sprinklr. As a result, CMOs increasingly find themselves becoming the advocates of corporate digital transformation, to ensure the company is using technology to engage and delight end users.