A number of scientists are emphasizing the tremendous challenger that will soon be posed when the depletion of fossil fuel supplies coincides with an alarming increase in the global population. They highlight agriculture, which is heavily dependent not only on gasoline to fuel machinery but also on the petrochemicals without which today’s synthetic fertilizers and pesticides could not be manufactured. But for the latter two, crop yields would be only a fraction of what they are. To assume that ...

A number of scientists are emphasizing the tremendous challenger that will soon be posed when the depletion of fossil fuel supplies coincides with an alarming increase in the global population. They highlight agriculture, which is heavily dependent not only on gasoline to fuel machinery but also on the petrochemicals without which today’s synthetic fertilizers and pesticides could not be manufactured. But for the latter two, crop yields would be only a fraction of what they are. To assume that an abundant source of renewable energy will be a panacea is to ignore these vital non-fuel uses of petrochemicals.

Then there is the challenge posed to the current levels of mobility. As a fuel, gasoline has an unrivalled portability compared to electricity, which requires bulky batteries, and hydrogen, which is notoriously difficult to store. Biofuels might seem like an alternative but the energy (currently in the form of fossil fuels) consumed when converting corn into bioethanol, for instance, greatly exceeds the output when the fuels is utilized. In any case, once the crisis in the food supply looms large it will not make sense to divert food crops to other uses.

There seems to be a widespread belief that the era of oil dependency is coming to an end. There is a widespread complacency resting on the assumption that the experts will come up with a technological remedy making for a completely pain-free transition. Scientists such as Walter Youngquist argue that tis assumption may be mistaken and that the remaining resources might only support half of the current global population. In his opinion, the absence of a realistic alternative to fossil fuels will mean, amongst other things, that the first priority will be to curb the demand for food.

(http://www.fullspace.digitalcounterrevolution.co.uk/ecpe-practice-read…)

The underlined word “which” in the first paragraph refers to _______________.