This has a lot to do with the unrest in Nigeria, but also with the production loss after the hurricanes in the Gulf of Mexico, the decline in Iraq since the 2003 war, and the decline in Venezuelan output since 2002.

Cycles of shortage and surplus characterize the entire history of oil.

The world has produced about 1 trillion barrels of oil since the start of the industry in the nineteenth century. Currently, it is thought that there are at least 5 trillion barrels of petroleum resources, of which 1.4 trillion is sufficiently developed and technically and economically accessible.

The starting point for energy security today as it has always been is diversification of supplies and sources.

But eventually it's a question of access: Getting access to fields is on top of the oil companies' agenda. We see a substantial build-up of supply occurring over the coming years.

In the mid-1980s, operating problems took [nuclear] plants off-line so often that, on an annual basis, they operated at only about 55 percent of their rated total generating capacity. Today, as a result of several decades of experience and an intense focus on performance ... nuclear plants in the United States operate at over 90 percent of capacity. That improvement in operating efficiently is so significant in its impact that it can almost be seen as a new source in electric power itself.

In a world of increasing interdependence, energy security will depend much on how countries manage their relations with one another. That is why energy security will be one of the main challenges of foreign policy in the years ahead. Oil and gas have always been political commodities.