The pensions crisis or pensions timebomb is the predicted difficulty in paying for corporate or government employment retirement pensions in various countries, due to a difference between pension obligations and the resources set aside to fund them. The basic difficulty of the pension problem is that institutions must be sustained over far longer than the political planning horizon. Shifting demographics are causing a lower ratio of workers per retiree; contributing factors include retirees living longer (increasing the relative number of retirees), and lower birth rates (decreasing the relative number of workers, especially relative to the Post-WW2 Baby Boom). An international comparison of pension institution by countries is important to solve the pension crisis problem. There is significant debate regarding the magnitude and importance of the problem, as well as the solutions. One aspect and challenge of the "Pension timebomb" is that several countries' governments have a constitutional obligation to provide public services to its citizens, but the funding of these programs, such as healthcare are at a lack of funding, especially after the 2008 recession and the strain caused on the dependency ratio by an ageing population and a shrinking workforce, which increases costs of elderly care. For example, , the estimates for the underfunding of the United States state pension programs ranged from $1 trillion using a discount rate of 8% to $3.23 trillion using U.S. Treasury bond yields as the discount rate. The present value of unfunded obligations under Social Security as of August 2010 was approximately $5.4 trillion. In other words, this amount would have to be set aside today so that the principal and interest would cover the program's shortfall between tax revenues and payouts over the next 75 years. Some economists question our ability to address the problem by saving now. Storing funds by governments, in the form of fiat currencies, is the functional equivalent of storing a collection of their own IOUs. Since the government is responsible for printing the currency, the act of printing now, saving it, and then releasing it into circulation later is economically equivalent to simply printing it later. This suggests that the hoarding of cash by the government today to address the later crisis is a non-solution. Reform ideas can be divided into three primary categories: Addressing the worker-retiree ratio by raising the retirement age, and changing employment and immigration policy Reducing obligations by shifting from defined benefit to