Ecologists rarely mention fossil fuel use when discussing sustainability. However nearly all human societies, rich or poor, are overwhelmingly dependent upon oil, which supplied about 40 percent of US and Global energy use in 2007, and natural gas, which supplied another 20 or so percent.  Our societies have also been dependent upon the growth of oil and gas supplies to support additional agricultural and economic activity needed by increasing humans.  Thus there is considerable concern about whether “peak oil” (meaning the point for a region, a nation, or the world at which oil production no longer increases but enters a plateau or decline) has occurred for the world, or might soon.  If true then the “end of cheap oil” will be upon us. A peak in natural gas appears not too far behind, especially in North America. The increasing energy cost of these fuels and their substitutes (energy return on [energy] invested, or EROI) may be even more important.  Because of the critical importance of petroleum for essentially everything we do agronomically and economically, there are major concerns as to what the implications might be for the sustainability of human societies and their economies. I explore the relation of energy to economics and sustainability for 130 countries with a series of innovative and empirically-based graphical and modeling approaches.  Do conventional economic models and tools work, and sustainability for humans expand, only when it was possible to readily expand the petroleum and other fuel supplies? 

Results/Conclusions

Most aspects of economic activity and food production in the 130 countries of the world analyzed are closely associated with, in many cases linearly, with energy use. The exceptions are a relatively few highly industrialized nations.  Our main economic concepts have worked principally because they were derived during a period of our expanding ability to pump more oil out of the ground to feed more people and to implement whatever policy we desired. Conventional economic approaches may have much less relevance during times of contracting energy supplies regardless of our desire to make our world “green”.  Are our sustainability, our economies and our finances beholden to the laws of physics?  The answer is in many ways yes.  Thus the sustainability question becomes: can we improve upon our ability to do the necessary economic and financial analyses needed for sustainability by using procedures that depend on the energy available to undertake the activity in question?