Despite the aura of omnipotence most empires project, a look at their history should remind us that they are fragile organisms. So delicate is their ecology of power that, when things start to go truly bad, empires regularly unravel with unholy speed: just a year for Portugal, two years for the Soviet Union, eight years for France, 11 years for the Ottomans, 17 years for Great Britain, and, in all likelihood, 22 years for the United States, counting from the crucial year 2003.

Future historians are likely to identify the Bush administration's rash invasion of Iraq in that year as the start of America's downfall. However, instead of the bloodshed that marked the end of so many past empires, with cities burning and civilians slaughtered, this twenty-first century imperial collapse could come relatively quietly through the invisible tendrils of economic collapse or cyberwarfare.

But have no doubt: when Washington's global dominion finally ends, there will be painful daily reminders of what such a loss of power means for Americans in every walk of life. As a half-dozen European nations have discovered, imperial decline tends to have a remarkably demoralizing impact on a society, regularly bringing at least a generation of economic privation. As the economy cools, political temperatures rise, often sparking serious domestic unrest.

Available economic, educational, and military data indicate that, when it comes to U.S. global power, negative trends will aggregate rapidly by 2020 and are likely to reach a critical mass no later than 2030. The American Century, proclaimed so triumphantly at the start of World War II, will be tattered and fading by 2025, its eighth decade, and could be history by 2030.

Significantly, in 2008, the U.S. National Intelligence Council admitted for the first time that America's global power was indeed on a declining trajectory. In one of its periodic futuristic reports, Global Trends 2025, the Council cited "the transfer of global wealth and economic power now under way, roughly from West to East" and "without precedent in modern history," as the primary factor in the decline of the "United States' relative strength - even in the military realm." Like many in Washington, however, the Council's analysts anticipated a very long, very soft landing for American global preeminence, and harbored the hope that somehow the U.S. would long "retain unique military capabilities... to project military power globally" for decades to come.

No such luck.  Under current projections, the United States will find itself in second place behind China (already the world's second largest economy) in economic output around 2026, and behind India by 2050. Similarly, Chinese innovation is on a trajectory toward world leadership in applied science and military technology sometime between 2020 and 2030, just as America's current supply of brilliant scientists and engineers retires, without adequate replacement by an ill-educated younger generation.

By 2020, according to current plans, the Pentagon will throw a military Hail Mary pass for a dying empire.  It will launch a lethal triple canopy of advanced aerospace robotics that represents Washington's last best hope of retaining global power despite its waning economic influence. By that year, however, China's global network of communications satellites, backed by the world's most powerful supercomputers, will also be fully operational, providing Beijing with an independent platform for the weaponization of space and a powerful communications system for missile- or cyber-strikes into every quadrant of the globe.

Wrapped in imperial hubris, like Whitehall or Quai d'Orsay before , the White House still seems to imagine that American decline will be gradual, gentle, and partial. In his State of the Union address last January, President Obama offered the reassurance that "I do not accept second place for the United States of America." A few days later, Vice President Biden ridiculed the very idea that "we are destined to fulfill [historian Paul] Kennedy's prophecy that we are going to be a great nation that has failed because we lost control of our economy and overextended." Similarly, writing in the November issue of the establishment journal Foreign Affairs, neo-liberal foreign policy guru Joseph Nye waved away talk of China's economic and military rise, dismissing "misleading metaphors of organic decline" and denying that any deterioration in U.S. global power was underway.

4 Scenarios for the Coming Collapse of the American Empire