Musk, who has blazed a trail for all-electric cars with his expensive but popular Teslas, said the oil and gas resources that fracking could potentially release could be 10 times the current available hydrocarbons worldwide.
That could spell low prices for generations.
“The potential harm to the climate is much greater than it was before,” he said in Detroit.
Musk said it was now “more urgent” that mainstream automakers step up investment in electrics as low oil prices prove an incentive to buyers of conventional cars.
“I think we are really going to regret the amount of carbon we are putting in the oceans and atmosphere,” he said.
“If we can maybe go electric sooner, that would be much better for the world.”
Musk, meanwhile, said Tesla was on track despite sales problems in China and the delay to the eagerly-awaited Model X crossover. He said the company would release the gull-winged Model X in the early second half of this year and is aiming to produce half a million electric cars by 2020, up from more than 30,000 in 2014.