The energy transition “is not going smoothly,” the Chief Executive of Saudi Aramco, Amin Nasser, said on Thursday, calling for continued investment in oil and gas until low-carbon energy could grow and mature enough to meet rising energy demand.

At an online conference carried by Reuters, Nasser said: “We have to acknowledge that the current transition is not going smoothly.”

“We all agree that to move towards a sustainable energy future a smooth energy transition is absolutely essential but we must also consider the complexities and challenges to get there.”

In recent months, he has repeatedly warned energy analysts and industry that investment in oil and gas will be required even as renewable energy installations grow.

At a forum in Saudi Arabia earlier this week, Aramco’s CEO said: “As the energy transition unfolds, oil and gas will remain essential in many ways. …Yet, this is not the popular narrative … which is built on un-realistic assumptions.”

At the World Petroleum Congress in Texas last month, Nasser warned that a hasty switch to renewable energy would result in soaring inflation and societal upheaval. To avert such a scenario, Aramco’s senior executive said that oil and gas investments must continue.

“Right now, the world is facing an ever more chaotic energy transition. Several highly unrealistic scenarios and assumptions about the future of energy are clouding the picture,” he said

“Energy security, economic development, and affordability imperatives are clearly not receiving enough attention. Until they are, and unless the glaring gaps in the transition strategy are fixed, the chaos will only intensify,” he added.