In Steve Hallett's new book "Life Without Oil: Why We Must Shift to a New Energy Future," the Purdue University plant scientist tackles the world's energy problems from a different perspective – that of an ecologist.

Hallett, an associate professor in Purdue's Department of Botany and Plant Pathology, argues that energy is the driver of our society's success and that the loss of abundant supplies of oil will significantly impact all facets of society.

"You tend to hear about oil from oil guys and plants from plant guys. And that makes perfect sense. What you don't get is the connections among those fields," said Hallett, who authored the book with Jon Wright, a journalist who has extensively covered energy issues. "Making connections is what ecologists do."

In an admittedly pessimistic view of the world's energy issues, Hallett argues that throughout history all societies have collapsed, usually from the loss of a necessary resource. For our current society, that resource could be oil.

"We have a couple of choices: We either collapse, or we shift to something else," Hallett said.

A graph in the book shows the use of oil for energy as a large spike that began its ascent about a century ago and reaches its final descent about a century from now. That spike, Hallett said, is like an ecological input. The upward portion of the spike has advanced society rapidly, while the downward may create a difficult future.

Energy-rich oil has improved our ability to produce more food, both agriculturally and through fishing, for example. That has led to a rapid growth in world population, which necessitates more oil to keep people fed. That oil, Hallett said, is causing spikes in carbon emissions, which is a factor in climate change.

"You can see the sudden explosion of positive and negative through the same window," Hallett said. "The bigger our economy gets, the faster we use fossil fuels and the faster we run out."

Hallett believes the world has reached its peak in oil production - give or take a decade - and is heading into an oil decline. The world will either have to significantly cut energy use or find an alternative source.

Hallett also discourages the belief that human ingenuity will create a solution. He said the difficult truth is that the world can't continue growing, either physically or economically, and expect to survive.

"We're constantly faced with these intractable problems, and we usually find the answer in more of something. We've come to the point where that won't work," Hallett said. "We've filled up the world with enough people, exhausted too many of its resources, and we need to settle into a lifestyle where we don't feel the need for constant progress and growth. You can't grow forever. We will reach limits, and the book argues that we are reaching those limits.

"There are some things that just run out and cannot be replaced, and oil is one of them."

"Life Without Oil: Why We Must Shift to a New Energy Future" was released in March by Prometheus Books. It retails for $26 and is available through most bookstores and online booksellers.