An ongoing price slump is rattling the industry and weakening petrostates. How will low prices change the world? Here’s everything you need to know: How cheap is oil? Prices have hovered between $40 and $50 a barrel for the past year — far below the pre-collapse high of $147 a barrel in 2008. The U.S. shale revolution continues to cause a global glut in supplies of the liquid fossil fuel, depressing the price, and energy company Shell says it is bracing for a world where oil prices might stay “forever low.” Oil prices have historically been highly volatile, and demand for the commodity is higher than ever. But if the glut continues, it will pose an existential threat to the monarchy ruling Saudi Arabia, which relies on oil for as much as 70 percent of the kingdom’s income. Other petrostates, including Venezuela and Russia, are already in a state […]