NEW YORK

--The outcome of November's presidential election will affect the entire world. Yet until the attack on our consulate in Libya, issues of foreign policy and globalization were nearly absent from the political discourse.

There was talk at both parties' political conventions about American exceptionalism and the nation's exalted place in the world, but little was said about the need for common action with other nations to secure our imperiled common planet. Even former President Clinton stuck to the domestic agenda at his party's Charlotte, N.C., convention.

In an age of unprecedented cosmopolitanism and interdependence, our election rhetoric has been parochial, inward and self-absorbed.

The talk has been about American jobs, American civil rights, American health care. These are all crucial topics, but we need to think of them in international terms. We are American citizens, yes, but we are also citizens of the world. And the complex issues we face today don't honor the borders of nations.

Take climate change. Other than Mitt Romney's throwaway line ridiculing the rise of sea levels, there has been little substantive discussion of this global peril. The parties, meanwhile, advocate "energy independence," something that is neither desirable nor achievable in this era. The oil market is truly global, and no country can control prices that fluctuate with global supply and demand. Solely national markets simply do not exist anymore, not in steel, not in oil, not even in labor. Our immigration problems are a function of a global labor market that is beyond our ability to control.

We live in an age of interdependence, and the challenges we face--climate change, immigration, pandemic illness, the drug trade, terrorism, financial stability--can't be addressed without global cooperation. The 21st century will be neither an American century nor a Chinese century; it will be a world century. It will belong to all of us or to none, and we must decide together how to shape it.

This is realism, not idealism. But it is hard for politicians to talk realistically about interdependence when citizens punish them for it, calling them "European" or "socialist" or "un-American." In his first year in office, President Obama gave speeches in Istanbul and Cairo in which he urged global cooperation and actually used the term "interdependence." Since then he has learned to avoid cosmopolitanism in his politics. Thinking globally may be prudent policy, but it's political poison.