Global oil markets are facing down a “decade of disorder” if long-term supply projects aren’t put into the pipeline, a former chief of the Energy Information Administration (EIA) said Tuesday.

Adam Sieminski, who headed EIA from June 2012 until January, discussed global supply trends during a panel discussion in Houston on the second day of CERAWeek by IHS Markit. He now is the James R. Schlesinger Chair for Energy and Geopolitics at DC-based Center for Strategic and International Studies, a bipartisan, nonprofit policy research organization.

A wave of global populism, evidenced by the United Kingdom’s potential exit from the European Union, geopolitical events and trade wars, create “a lot of uncertainties…in a lot of different areas,” Sieminski told the audience.

An uplift in oil prices has encouraged U.S. unconventional producers to raise rigs and ramp up output. However, those short-term supply projects aren’t enough to compensate for depressed conventional oil production, which is the bulk of worldwide supply, he said.

The expected shortfall in conventional output “might bite us at some point,” he said.

ConocoPhillips CEO Ryan Lance told a CERAWeek audience that to avoid the crush that followed the recent oil price debacle, energy operators should be “prepared for longer, more frequent declines in prices.”

Prices have stabilized, and operators are becoming “a lot more efficient,” but market volatility could cause oil prices to “snap back” within a couple of years, said Lance, who runs the world’s largest independent producer.

Many U.S. operators claim their breakeven costs to produce U.S. unconventional oil have fallen to around $50/bbl. Sieminski puts the average price today at closer to $55-60/bbl.

Even so, current breakevens may be enough to secure profits for U.S. operators, but prices still aren’t high enough to build global supply to meet demand into the 2020s, he said.

What’s also unclear is the impact of what Sieminski called an “experiment” by the Organization of the Petroleum Exporting Countries (OPEC) to temporarily reduce global oil supply.

OPEC’s decision, which is to be reviewed in May, has been the talk of the conference, both in plenaries and in the hallways. Saudi Arabia’s Khalid Al-Falih, minister for energy, industry and mineral resources, who also spoke Tuesday, said the formal agreement was not a permanent pullback nor a signal that U.S. unconventional operators should turn up the dial.

Hess Corp. CEO John Hess, who spoke at CERAWeek on Monday, also warned that a significant worldwide oil supply crunch could be looming because many global projects, particularly long-term deepwater facilities, have been delayed or canceled.

“As an industry we’re not investing enough for supply growth to keep up with demand growth,” Hess said. Decreasing spend, particularly in the resource-rich (but expensive) offshore, may cause supply to plateau or decline as global demand is rising, he said.

A supply deficit is possible as soon as three years and within five, when the reductions in capital investments should begin to show up in falling offshore supply, Hess said.

“We’re not investing enough to keep the offshore investment pipeline full,” Hess said. While shale operations are “back in business and starting to grow again,” the same is not true of more capital-intensive projects.

Many executives at this week’s conference expressed support for Trump administration proposals to scale back energy regulations and speed infrastructure build-out. The administration could enable higher domestic oil and gas production if tax reforms are done, and if federal regulations are eased for infrastructure, Lance said.

“I think we’re looking for smart regulation that has a definable cost and benefit,” the ConocoPhillips chief said.