> The original poster seemed to imply that it would take millions of years worth of solar energy to "put back" all the CO2 into hydrocarbons. Really? Not the

> The original poster seemed to imply that it would take millions of years worth of solar energy to "put back" all the CO2 into hydrocarbons. Really? Not the way I read his message. I don't know what you've read (and why it is "seemed to imply" and not some quote that would support your claim), I know only this part of his message: "we released millions of year worth of concentrated solar energy in the span of a century." And if you analyze what actually happened on Earth, it is really billions of years of photosynthesis that were needed for this to happen (to produce the conditions that the concentrated carbon remained in the crust). You write that you've discovered that only for a geologically "short" time the carbon was stored. Yes, indeed. But that geologically short time is compared to the billions of years where the conditions weren't right, both before and after. And you still ignore what I wrote: without the pure oxygen, which was produced by the cyanobacteria using photosynthesis(!), there would be no geologically short period of the more active storage. So yes, the fossil fuels are the still result of the almost 3 billion years of photosynthesis. And yes, it is an "accident" in a sense that everything needed to happen exactly as it happened, it wasn't in any way inevitable. Which should actually make us appreciate even more that we probably used half of all the easily obtainable oil from the crust in just a 100 years. And yes, we are burning the hydrocarbons from the crust and releasing the CO2 back to the atmosphere, 300 millions of years after the Carboniferous, and it won't be good for us. Together with the Holocene extinction, humans already immensely changed the nature.