Tesla CEO Elon musk said that transitioning to renewable energy sources will be one of the most difficult tasks the planet will face, and it may take several decades to complete. Talking to reporters, the automaker emphasized that to maintain civilization, it will be necessary to continue to extract oil and gas, as sustainable sources of energy are developed and deployed.

During an energy conference in Norway, Musk said, “Realistically, I think we need to use oil and gas in the short-term, because otherwise civilization will crumble.” Musk added that he does not “demonize” fossil fuels, however it is important that, “we must have a clear path to a sustainable energy future.”

Musk said: “I think some additional exploration is warranted at this time,” when asked if Norway should still drill for oil and gas. He added, “One of the biggest challenges the world has ever faced is the transition to sustainable energy and to a sustainable economy … that will take some decades to complete.”

Musk also advanced the idea of offshore wind and power generation in the North Sea, combined with stationary battery packs, noting it could become a key source of energy. “It could provide a strong, sustainable energy source in winter,” he added.

Previously Musk had called on Europe to return to nuclear power and boost domestic fossil fuel production to offset Russia’s influence in the region.