The increased use of hydrofluorocarbons (HFCs) in the production of refrigerators, air conditioners, and other products could play a significant role in accelerating global warming, a new UN report warns. Without stricter regulations, the United Nations Environment Program (UNEP) report says, the projected emissions of HFCs by 2050 could equal pouring nearly 9 billion tons of carbon dioxide into the atmosphere — or about one-third of current CO2 emissions. While introduced in the 1990s to replace ozone-depleting chlorofluorocarbons (CFCs), HFCs are also potent greenhouse gases — about 1,600 times more powerful in trapping heat in the atmosphere than carbon dioxide. And with the increase in world population and the continued growth of emerging economies, annual consumption of HFCs has doubled over the last decade to about 400,000 tons, according to the UNEP report. The most common type of HFC increased 10 percent annually from 2006 to 2010.