Given our present energy and climate predicament, it is interesting to contemplate how human history would have progressed in the absence of large supplies of coal, oil, and gas. Before efficient steam engines existed, heavy industry depended on mechanical water power to grind flour, saw wood, and so forth. Steam engines and coal helped kick off the path of development that leads to the present world, in which fossil fuels play critical roles as energy sources, inputs for agriculture, and feedstocks for chemical manufacture.
On a planet without fossil fuels, industrialization would probably have made use of mechanical water and wind energy for far longer. It is an open question whether such a society could ever have reached the point of being able to build current-generation renewables, such as electric wind and hydro turbines, solar photovoltaic panels, or concentrating solar arrays. It is possible, then, that only planets with ample and accessible supplies of fossil fuel are compatible with the development of things like spaceflight or computer networks. That could even be one explanation for the Fermi paradox: the question of why the vast observable universe hasn’t yet provided any signs of life outside our solar system.
The challenge now is to move beyond fossil fuel dependency, without losing the beneficial new capabilities that have largely arisen due to the use of those energy sources. Eventually, we need to reach a point where the whole lifecycle of energy production – including construction and dismantling of generation equipment – is accomplished in a zero carbon and sustainable way. We will also need to re-make global agriculture in a way that isn’t dependent on fossil fuels or fertilizers derived from them, as well as find ways to use biomass feedstocks in chemical manufacture. The fossil fuel era must be a one-off transition period in human history; at least, it must prove to be so if human history is to extend much longer.