If you were organizing dinner parties for the world, you would need to put out 219,000 more place settings every night than you had the night before. That is how fast the Earth's population is growing. But global agricultural production is currently failing to keep pace. A June 2012 report by the UN Food and Agriculture Organization (FAO) sees trouble looming ahead, warning that “land and water resources are now much more stressed than in the past and are becoming scarcer.”

Hunger continues to be one of humanity's greatest challenges despite the existence of a more-than-adequate global food supply equal to 2,800 kilocalories for every person every day. In measuring progress, policy-makers and concerned citizens across the globe rely on information supplied by the Food and Agriculture Organization (FAO), an agency of the United Nations. In 2010 the FAO reported that in the wake of the 2007–2008 food-price spikes and global economic crisis, the number of people experiencing hunger worldwide since 2005–2007 had increased by 150 million, rising above 1 billion in 2009. However, in its State of Food Insecurity in the World 2012 (SOFI 12) the FAO presented new estimates, having revamped its methods and reinterpreted its hunger data back to 1990. The revised numbers for the period 1990–1992 to 2010–2012 reverse the trend to a steadily falling one. Based on the FAO's new calculations, extreme undernourishment peaked in 1990 at a record-breaking one billion, followed by a significant decline through 2006, when progress stalled but did not reverse (see chart below).

A global ethic for the twenty-first century will be different from that of the twentieth century. While themes of normative and political continuity will exist, humankind's main moral challenges have changed. Between the two centuries lie the end of the cold war, the terrorist attacks of September 11, 2001, the global financial crisis, and the double transformation of the structure of power in world politics and the norms of sovereignty and intervention. Nuclear weapons will remain high on the agenda of a global ethic, but they will not hold as dominant a place as they did in the past century. This essay, focused on the continuing moral challenge of nuclear weapons, recalls the intellectual and moral lessons of the last century and identifies three leading issues in nuclear ethics today: post–cold war challenges to nonproliferation and deterrence, the new challenges posed by the terrorist threat, and recent proposals for Going to Zero.

Nuclear weapons proliferation is at the top of the news these days. Most recent reports have focused on the nuclear efforts of Iran and North Korea, but they also typically warn that those two acute diplomatic headaches may merely be the harbingers of a much darker future. Indeed, foreign policy sages often claim that what worries them most is not the small arsenals that Tehran and Pyongyang could build for themselves, but rather the potential that their reckless behavior could catalyze a process of runaway nuclear proliferation, international disorder, and, ultimately, nuclear war.

Today, the nuclear regime is widely perceived to be in crisis. While part of this crisis has to do with direct challenges to the regime posed by the illicit nuclear programs of North Korea and Iran, from the perspective of much of the developing world, the issues facing the nonproliferation regime are overwhelmingly about the justice and fairness of the regime's norms, rules, and procedures. Indeed, it is difficult to identify a security regime today where equity issues are more central to debates about its future than the nuclear nonproliferation regime. Of the three regimes for controlling weapons of mass destruction (chemical, biological, and nuclear), it is in the nuclear regime that issues of justice and fairness appear most critical to long-term sustainability and viability.

We have the power of choice over nuclear weapons. But we do not feel our power. Instead, we feel their power. They are larger than life. They loom over us, seemingly beyond our control, shrouded in myth and dark mystery. Because of their power and our feeling that nuclear weapons are unique, we believe that these weapons require a special set of moral rules, specially tuned to the separate world where nuclear weapons dwell.

For more than four decades the twin goals of nuclear nonproliferation and disarmament have been an almost unchallenged objective of the “international community.” Like drought prevention, or bans on the use of child soldiers, nonproliferation remains a mostly uncontroversial, largely universalistic initiative to which few object. The proponents of nonproliferation are fond of stressing that the Treaty on the Nonproliferation of Nuclear Weapons (NPT) has more signatories than any other arms control treaty. Who would not want to prevent more states from obtaining nuclear weapons? And who, for that matter, would oppose the ideal of a world free of such weapons?