A decade ago, the news that the world’s top oil and gas companies had less than 12 years of production left in their reserves might have caused a panicked sell-off in their shares. But as consumers try to move away from fossil fuels to cleaner and cheaper energy sources, investors and executives say reserve size is no longer the gold standard for measuring the value and health of a company. The cost of developing existing reserves and the amount of carbon those reserves produce has now become more important, they say. This is leading to a profound shift in company strategies. “The quality of reserves and the commercial viability of reserves has eclipsed the quantity of reserves by far in recent years,” said Adi Karev, Global Leader for Oil and Gas at EY.