If we continued to use fossil fuels at current rates, Our World in Data estimates that we would have 114 years of coal left and just over 50 years each of oil and natural gas. Of course, that’s based on known reserves, so the actual amount of fossil fuels left in the world is likely to be higher. But as fossil fuel reserves get harder to find, the cost of production would increase, raising concerns of a “peak oil” crisis. But the risk of running out of oil isn’t the only reason to end the burning of fossil fuels and rethink our energy system. There are other downsides to fossil fuel production, including environmental damage and human health effects.