China will have to spend up to US$86 billion a year to reach its greenhouse-gas reduction targets, according to a UN report. Beijing wants to cut carbon intensity – the amount of carbon produced per unit of GDP – by 40-45% by 2020. While reaching the 40% mark could save the country US$30 billion a year through increases in energy efficiency, once China hits 51% its efforts will cost US$86 billion a year, or 1.2% of projected GDP. The cost of cutting carbon intensity by 91% on 2005 levels by 2050 would come in at US$1.6 trillion a year. These calculations were carried out by the UN Development Program in collaboration with Renmin University, the Wall Street Journal reported. The authors of the report say that China must act now to find more ways to cut emissions – such as cap-and-trade plans and a carbon tax – before the increased energy demands created by ongoing urbanization become unmanageable.