The United Nations published new predictions on the size and age of the world's population 300 years from now. It says that if fertility stays at the current level, the global population could rise to 134 trillion. But in its medium-case scenario the UN sees the world's population rising from 6.3 billion to about 9 billion in 2300. The UN publishes long-range projections to help environmental scientists and policy-makers assess implications of dramatic change in world population. The report says the increase is a clear indication that fertility levels are unsustainable.