I have a feeling those graphs are more than a little fishy - the bottom one especially. Retirement costs went up ~5X from 2000 to 2010? And they'll go up by the same from 2010 to 2020? I call BS.
1) Many pensions are underfunded. The state has to play "catch up" because they weren't putting enough money in the fund in the past.
2) Pension funds play the stock market. In a recession, the fund needs more money because the market is down.
3) (I'm not sure this is the case for California, but it's definitely the case for the federal gov't) The gov't often guarantees pensions issued by bankrupt companies. The gov't just takes on the extra debt, and often bankrupt companies don't keep up with their pension contributions.
1. Increased promises to the public sector workforce.
2. The need to make up shortfall in the funding due to market declines.
3. The need to make up shortfall because the funding was insufficient to begin with, owing to accounting ... creativity.
4. The boomers are just now hitting retirement, so the number of people retiring in a given year is increasing (Actually, it'd be interesting if somebody could pull out some hard numbers on this - I've heard this spoken of anecdotally a lot lately).
5. Retirees are drawing on their pensions for longer because they have longer lives.