When the glitterati walk the red carpet on Sunday for Hollywood's biggest night, the very white, very male make-up of this year's Academy Award nominees is likely to become the unfortunate punchline of a few jokes.

But of course, it's not funny. The stunning lack of diversity on this year's Oscars shortlist has already sparked plenty of serious discussion. All 20 of the nominees in the acting category are white, and there is not a single woman in the directing or screenwriting categories. One year after "12 Years a Slave" won an Academy Award, we're still waiting for a tipping point that significantly changes Hollywood's landscape.

So how does such an insular industry open itself up? How do we make sure more people of racial and ethnic backgrounds can get jobs within the industry, good financing for great films, and positions in the Academy of Motion Picture Arts & Sciences?

The answer isn't an easy one. Better diversity among members of the Academy, which votes on the Oscar nominees and winners, might help. A 2013 study by the Los Angeles Times put membership of the 6,000 members of the Academy at 93 percent white and 76 percent male. The average age is 63.

With demographics like that, it's hard for the group's membership as a collective whole to reflect the tastes, diversity and interests of their audiences. As Darnell Hunt, a UCLA professor and director of the Ralph J. Bunche Center for African American Studies, told the Associated Press, this year's nominees were "more or less an accurate reflection of the way the industry is structured and the way the Academy is populated."

Meanwhile, others say it isn't a bias problem among Academy members, but an overall hiring problem in the industry. A lack of racial diversity among the nominees doesn't mean Academy voters didn't cast any ballots for, say, black or hispanic actors, but that there need to be more people of varying backgrounds in the mix of potential winners to start. "AMPAS honchos have been working hard to diversify membership and to work on diversification within executive and creative ranks," wrote Tim Gray in Variety. "It all starts with the hiring."

But improving diversity through a better mix of Academy members and more hiring of women and minorities will likely take a long time. In an industry this reliant on personal contacts and networks, even good strides in making diverse hires could be slow to show results.

And as the Los Angeles Times noted, the Academy's size means that even if it replaces its outgoing members with more diverse ones — a concerted effort is being made to add younger people, women and minorities — it would hardly make a dent. The Academy would still be 89 percent white and 72 percent male by 2023, the newspaper reported.

As with most things, change is likely to come fastest if there's real leadership behind it. An A-list actor could decide to require, as one professor suggested, a diverse cast as part of his or her contract. A studio head might make funding ethnically diverse films and women-directed movies a strategic priority, holding executives accountable for it and investing more in marketing black stars.

And the Academy president might make addressing the diversity problem an even bigger focus. Cheryl Boone Isaacs, who is actually the Academy's first African American president, has continued efforts to diversify the Academy's membership and has said she would personally "love to see and look forward to see a greater cultural diversity among all our nominees in all of our categories." But when asked by New York Magazine whether the organization has a problem with recognizing diversity, she also reportedly said: "not at all."

This year's homogeneous list of nominees might seem to suggest otherwise. Not since 1998 have the 20 actors on the short list all been white. That fact may have sparked online outrage, and it may be an uncomfortable truth. But it is also powerful. It gives leaders in Hollywood a legitimate and telling script to use to spotlight how much still needs to change.

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