In almost every part of the world, long-festering problems can be solved through closer co-operation among neighbouring countries.
The EU provides the best model for how neighbours that have long fought each other can come together for mutual benefit. Ironically, today's decline in American global power may lead to more effective regional co-operation.
This may seem an odd time to praise the EU, given the economic crises in Greece, Spain, Portugal and Ireland. Europe has not solved the problem of balancing the interests of strong economies in the north and those of weaker economies in the south. Still, the EU's accomplishments vastly outweigh its current difficulties.
The EU has created a zone of peace where once there was relentless war. It has provided the institutional framework for reuniting western and eastern Europe. It has fostered regional-scale infrastructure. And the EU has been a global leader on environmental sustainability.
For these reasons, the EU provides a unique model for other regions that remain stuck in a mire of conflict, poverty, lack of infrastructure and environmental crisis.
In most other regions, political divisions have their roots in the Cold War or the colonial era. During the Cold War, neighbours often competed with each other by "choosing sides" - allying themselves with either the US or the Soviet Union.
Pakistan tilted towards the Americans, India towards the Soviets. Countries had little incentive to make peace with their neighbours as long as they enjoyed the financial support of the US or the USSR. In fact, continued conflict often led directly to more financial aid.
The US and Europe often acted to undermine regional integration, which they believed would limit their roles as power brokers.
Today's reality, however, is that great powers can no longer divide and conquer other regions, even if they try. The age of colonialism is finished, and we are now moving beyond the age of US global dominance.
Recent events in the Middle East and Central Asia clearly reflect the decline of US influence. The failure of the US to win any lasting geopolitical advantage through the use of military force in Iraq and Afghanistan underscores the limits of its power, while its budget crisis ensures it will cut its military resources sooner rather than later. Similarly, the US played no role in the political revolutions under way in the Arab world.
President Barack Obama's recent speech on the Middle East is a further display of America's declining influence in the region. The speech drew the most attention for calling on Israel to return to its 1967 borders, but the effect was undercut when Israel flatly rejected the US position.
The rest of the speech was even more revealing, though it drew little public notice. When Mr Obama discussed the Arab political upheavals, he noted the importance of economic development. Yet when it came to US action, the most that the US could offer financially was: slight debt relief for Egypt - US$1 billion (Dh3.67bn);scant loan guarantees - $1bn; and some insurance coverage for private investments.
The real message was that the US government would contribute very little financially to the region's economic recovery. The days when a country could depend on large-scale US financing are over.
We are, in short, moving to a multi-polar world. The Cold War's end has not led to greater US dominance, but rather to the dissemination of global power to many regions.
Each region, therefore, will have to secure its own future. Of course, this should occur in a context of co-operation across regions as well as within them.
The Middle East is in a strong position to help itself. There is a high degree of economic complementarity between Egypt and the Gulf States.
Egypt can supply technology, manpower and considerable expertise for the Arab region, while the Gulf provides energy and finance, as well as some specialists. The long-delayed vision of Arab economic unity should be returned to the table.
Israel, too, should recognise that its long-term security and prosperity will be enhanced as part of an economically stronger region. For the sake of its own national interests, Israel must come to terms with its neighbours.
Other regions also will find that the decline of US power increases the urgency of stronger co-operation between neighbours. Some of the greatest tensions in the world - say India and Pakistan, or North and South Korea - should be defused as part of region-wide strengthening.
As the EU shows, ancient enmities can be turned into mutually beneficial co-operation if a region looks ahead, to resolving its long-term needs, rather than backward, to its long-standing rivalries and conflicts.
Jeffrey D Sachs is a professor of economics and director of the Earth Institute at Columbia University. He is also a special adviser to the UN secretarygeneral on the Millennium Development Goals.
* Project Syndicate