Makes no sense that fossil fuels would depend on global warming, since,
most of that fuel is created below ground and with the help of the underground forces, which forces are also moving the tectonic plates as we speak, and creating volcanoes, and changing the weather as we speak, for the short and long terms.
But, "fossil" fuels may be a misnomer, since, there are indications that, the planet creates that fuel without there having to be dead life, or organic, material available. Science has discovered methane and other "fuel" type material on other planets, so, what created that up there? There are no cows or dead organisms out there that we know of.
Oil and natural gas may be as plentiful today as they have always been, and they many continue to be "manufactured" by the natural forces, no matter what we do, and no matter how much organic material is available on the ground. There is much more organic material being deposited on the ground than ever in the history of the planet, but, that's not to say that we need to wait 100 or 200 million years before we get to use the "energy" created from that dead material.
