Alberta and Ontario, the two provinces with the most wind turbines up and whirling, face concerns that there are limits on how much power can be generated from the breeze before their electricity systems are destabilized.

Alberta recently put a temporary cap on wind generation at 900 megawatts -- a level it could reach as early as next year -- because of the uncertainty. And a report in Ontario released last week says that in some situations more than 5,000 MW of wind power, stable operation of the power grid could be jeopardized.

Demand-side Management Potential in Canada

How Long Can the World Feed Itself?

The miracle that has fed us for a whole generation now was the Green Revolution: higher-yielding crops that enabled us to almost triple world food production between 1950 and 1990 while increasing the area of farmland by no more than ten percent. The global population more than doubled in that time, so we are now living on less than half the land per person than our grandparents needed. But that was a one-time miracle, and it's over. Since the beginning of the 1990s, crop yields have essentially stopped rising.

The world's population continues to grow, of course, though more slowly than in the previous generation. We will have to find food for the equivalent of another India and another China in the next fifty years, and nobody has a clue how we are going to do that. But the more immediate problem is that the world's existing grain supply is under threat.

The New Middle East

Another factor that has helped bring about the end of the American era has been the failure of traditional Arab regimes to counter the appeal of radical Islamism. Faced with a choice between what they perceived as distant and corrupt political leaders and vibrant religious ones, many in the region have opted for the latter. It took 9/11 for U.S. leaders to draw the connection between closed societies and the incubation of radicals. But their response -- often a hasty push for elections regardless of the local political context -- has provided terrorists and their supporters with more opportunities for advancement than they had before.

Finally, globalization has changed the region. It is now less difficult for radicals to acquire funding, arms, ideas, and recruits. The rise of new media, and above all of satellite television, has turned the Arab world into a "regional village" and politicized it. Much of the content shown -- scenes of violence and destruction in Iraq; images of mistreated Iraqi and Muslim prisoners; suffering in Gaza, the West Bank, and now Lebanon -- has further alienated many people in the Middle East from the United States. As a result, governments in the Middle East now have a more difficult time working openly with the United States, and U.S. influence in the region has waned.