Here's something to think about the next time you're standing at the gas pump watching the numbers whiz by: Is this the beginning of the end? Is the world running out of oil?
While it's true that the price of gasoline today is only remotely related to the future of oil, that price does make people pay attention.
Lots of attention in fact, but little consensus.
On the one hand, it's obviously true that one day we will run out of oil — it's a non-renewable resource, laid down hundreds of millions of years ago.
It's also a fact that much of the oil that remains in the ground is, at this point, uneconomic to recover. It's either too deep, too remote or too tricky to extract.
So where does that leave us?
It depends who you believe. In the June issue of National Geographic, you can read an article called, "The End Of Cheap Oil." For the opposite perspective, read "Never Cry Wolf — Why The Petroleum Age Is Far From Over" in the current issue of Science.
If the amount of oil still in the ground is finite, and our consumption is rising steadily, where does the disagreement come from?
The National Geographic article presents the gloomy side of the picture.
The United States consumes 25 per cent of the world's oil, even though it represents only 5 per cent of the population.
The trend isn't good, either: U.S. consumption has climbed 25 per cent since the mid-1980s.
As well, China is rapidly becoming a major oil consumer — we couldn't actually expect the Chinese to keep riding bicycles when they could afford cars, could we? India has become a major consumer of automobiles as well.
There are no signs that the appetite for oil will decline or even level out.
Predicting the point at which oil supplies will decline to the point of crisis is a dicey business.
The late geophysicist M. King Hubbert gained fame for his accurate prediction in 1956 that oil production in the continental United States would peak in 1970.
He based this on something called the Hubbert curve, a graph that shows the production of oil growing from the beginning until half the recoverable amounts have been extracted, then slowing at about the same rate until there's no oil left to be had.
It's based on a number of factors, including an understanding of the geology of the planet and the inevitable vagaries of exploration and production.
The Hubbert curve has been tweaked over and over and applied to new estimates of oil reserves to refine the date at which world oil production is expected to peak.
In National Geographic, those predictions range from 2016 to 2040, a reflection of the inherent — and inevitable — uncertainty.
And while reaching the peak doesn't mean the end of oil, some experts have said it will mark the point where "the growth of the past gives way to the decline of the future."
The other side of the picture is presented in the Science article, written by Leonardo Maugeri of the energy company Eni Spa in Rome.
Maugeri dismisses Hubbert and his followers as "oil doomsters" and argues that the end of the oil age is far, far in the future. He contends that the major barrier to bringing more oil online is the reluctance of companies and governments to invest.
The potential of the reserves in the Kashagan field in Kazakhstan is a good example of where Maugeri and the doomsters part company.
The doomsters point to the fact that original, back-of-the-envelope estimates of the amount of oil there have declined from hundreds of billions of barrels to, at most, 33 billion barrels of difficult-to-extract oil.
Maugeri, on the other hand, sees a different trend at Kashagan: Estimates of recoverable reserves have escalated with each new exploration well, with only six such wells having been drilled to date.
The optimists like to say the Stone Age didn't end because we ran out of stone, and in one sense they're right.
Although we are a long way away from creating technologies that will replace oil, there will come a time when cost will dictate that it take its place alongside wood and coal as an energy source that no longer fits the bill.
Jay Ingram hosts the Daily Planet show on the Discovery Channel.