Despite persistently high oil prices, global energy demand will grow by 50 percent over the next two decades with continued heavy reliance on environmentally troublesome fossil fuels, especially coal and oil, the government predicted Wednesday.

The projections by the Energy Department's statistical agency said that without mandatory actions to address global warming, the amount of heat-trapping carbon dioxide flowing into the atmosphere each year from energy use will be 51 percent greater in 2030 than it was three years ago.