University of California tuition may increase by up to 16 percent each year for the next four years if the system doesn't get more state funding, according to a long-term budget plan released Wednesday.

The plan, which the UC regents will not vote on until at least November, could make in-state tuition as high as $22,068, not including the cost of room and board, books, and other fees. That would be almost double the current $12,192 tuition, which is already an increase of $1,800 over the tuition two years ago.

The state will give the University of California system about $2.37 billion this year -- $650 million less than in 2010. Meanwhile, pension, health care, energy and salary costs are rising, making it even more expensive to maintain the UC system. If funding remains stagnant, tuition will have to increase by the full 16 percent a year, as outlined in the budget plan. If funding increases by eight percent each year, tuition would correspondingly go up by eight percent instead -- less than the worst-case scenario, but still a serious hit.

The increases aren't certain yet, but students are already worried.

Rather than pressure the state, it could take pressure off, Claudia Magana, a UC Santa Cruz student and president of the UC Student Association, told the Los Angeles Times on Wednesday, implying that the existence of a detailed worst-case-scenario budget plan could give the state an excuse not to give the system more money.

Tuition has increased far more steeply and frequently at the University of California than at other public universities. In 2009, students held mass protests against a 32 percent increase, and in 2010 they fought yet another hike. During the 2009 protests, more than 100 students were arrested for trespassing after they took over buildings at several UC campuses, including UC Berkeley and UC Santa Cruz.

The constant tuition hikes are just one symptom of an ongoing budget crisis in California, in which the governor and legislature have tried to solve a huge deficit by cutting funding to public institutions, like universities.