What have been Obama's contributions on the world?

President Obama has been one of the most popular recent US presidents on the global stage with approval ratings of over 70 percent in many countries. He has been an exponent of multilateralism, attempting to work with global leaders and institutions, repairing the damage done by the "cowboy" style of unilateralism of the Bush administration.
He has worked towards global nuclear disarmament and managed to sign the New START arms control treaty with Russia as well as negotiating for Iran to give up its nuclear weapons development in exchange for relaxing sanctions. He also ordered the strike that killed the terrorist mastermind Osama bin Laden in 2011, and has participated in multilateral efforts to support the Arab Spring. He has opened up diplomatic relations with and visited Cuba, ending a long period of Cold War hostility between Cuba and the United States. 
He has been active in working on international efforts to mitigate global climate change. He steered the US economy out of the worst recession in recent decades, a move that has contributed to a global recovery.  He has also been a strong voice for human rights, gender equality, and LBGT rights. 
https://www.pewresearch.org/fact-tank/2015/06/24/7-charts-on-how-the-world-views-president-obama/