Crude across the globe is being used up faster than it is being replaced, raising the prospect of even higher oil prices in the coming years.

The world isn’t running out of oil. Rather, energy companies and petro-states, burned by 2014’s price collapse, are spending less on new projects, even though oil prices have more than doubled since 2016. That has sparked concerns among some industry watchers of a price spike that could hurt businesses and consumers.

The oil industry needs to add 33 billion barrels of crude every year to satisfy anticipated demand growth, particularly as developing countries like China and India are consuming more oil. This year, new investments are set to account for an increase of just 20 billion barrels, according to data from Rystad Energy.

The industry’s average decline rate—the pace at which output falls in a particular field or region without new investment—was 6.3% in 2016 and 5.7% last year, the Norway-based consultancy said. In the four years before the crash, that decline rate was 3.9%.

Any shortfall in supply could push prices higher, similar to when oil hit nearly $150 a barrel in 2008, some industry participants say.