That helps explains why oil has floated around $100 per barrel since 2011

That helps explains why oil has floated around $100 per barrel since 2011, despite the US boom. "The best explanation for that is that it's been a coincidence," said Michael Levi, an energy expert at the Council on Foreign Relations, in a recent interview. "We've had surprising US gains in production that have been offset by surprising losses elsewhere, due to geopolitical disruptions." But over the past month, those disruptions have started easing a bit. Libya's oil industry has started pumping out oil again — with exports unexpectedly rising 810,000 barrels per day in September.

It's also becoming clear that the Islamic State in Iraq and Syria (ISIS) likely won't threaten Iraq's biggest oil fields in the southern part of the country. And, at the same time, oil demand in Asia in Europe has started to weaken. So now oil prices are falling, from their June peak of around $115 per barrel down to around $92 per barrel at the start of October. Mind you, oil is still much, much pricier than it was a decade ago. And it's entirely possible that the recent drop could prove only temporary (after all, we saw price dips in 2012 and 2013, but new conflicts flared up in the Middle East and prices soon popped back up). But assuming the current drop is real — and sustained — it could have a very large impact around the world.