In a white paper discussing trends out to 2050, Europe’s largest oil company said the impending gap means tough, uncertain times lie ahead. It stopped short of concluding that consumers will face higher pries.

The gap “will have to be bridged by some combination of extraordinary demand moderation and extraordinary production acceleration,” the company said in the paper published on Wednesday.

The company said it will be “highly challenging” to do that while reducing carbon dioxide emissions.

Shell reported a fourth quarter net profit of $6.79 billion earlier this month.