If 2009 was marked by the arrival of President Barack Obama, then 2010 was the year when he tried, with varying degrees of success, to assert constructive U.S. leadership across the world. The U.S. has led humanitarian recovery efforts after environmental disasters in Haiti and Pakistan; spearheaded the fights against terrorism in Yemen, Afghanistan, and Iraq; and hosted peace efforts between Israel and Palestine, Pakistan and India, and China and Japan.

Some of those efforts bore fruit, such as in deescalating tensions in Iraq and East Asia or bringing aid to Haiti, while others have not. The war in Afghanistan and the effort to deter North Korean belligerence, despite global cooperation led by the U.S., have been largely frustrated.

But 2010 is also a year that saw traditional political borders fade. As sovereign debt crises hit Europe, members of the European Union found that economics now bind the continent more closely than ever before, for better or worse. In East Asia, China's rise united the rest of the once-disparate region. In Africa, the troubled Sub-Saharan nations found common cause in celebrating South Africa's hosting of the World Cup. The United Nations brought together the U.S., Russia, and China -- an unlikely trio -- to impose sanctions on Iran. And Wikileaks, the "stateless" radical transparency group, released thousands of tightly held U.S. secrets to Internet users across the world. Whatever 2011 brings, 2010 has showed us that, more than ever, we are all in it together in this world.