Every state pension system in Europe is a ponzi scheme nearing the the end of it's lifecycle. Almost all the money going in, is immediately distributed to current retirees and the fund levels are rapidly heading towards 0. Most estimates I've seen indicate that within a decade or 2 (without considerable rises in taxes) social security benefits will be around half what they are now in most of the developed world. The young are being royally screwed and paying into a system that offers them nothing.
The US's social security system has the exact same problem, but the key difference being that a decent percentage of Americans actually have 401k's (~50% i believe) that they've been funding for a long time. Pension plans/401k'like schemes in Europe are far less common and if they do exist they haven't been around anywhere near as long.
What will ultimately happen IMO is that everywhere in the developed world will just start means testing social security. Screwing everyone who saved up anything. We won't have a choice though, as it's the only way to not cripple the economy with exorbitant taxes and avoid large amounts of old frail people living on the street. The problem with Europe is they won't have enough people to screw over this way, and will end up with crippling taxes anyway that will cause more damage overall.