United Nations (CNN) -- On Tuesday, it was climate change. Wednesday, terrorists. And on Thursday, President Barack Obama confronted yet another emergency that threatens wide destruction overseas: the Ebola outbreak spreading in West Africa. Crisis management has become a hallmark of Obama's second term, perhaps seen nowhere better than at the annual United Nations General Assembly, where the world's leaders -- and their attendant calamities -- converge upon New York. Obama's three main issues here -- climate change, ISIS and Ebola -- each has the potential to rapidly spiral out of control, officials suggest, with the effects of a warming planet already being registered and Americans overseas already being killed both by terrorists with the Islamic State in Iraq and Syria and by the deadly virus spreading in Africa.
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Obama made clear at the U.N. that the U.S. isn't going to take the world's problems alone
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Obama's main issues at U.N. -- ISIS, climate change, Ebola -- could spiral out of control
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"Resolutions alone will not be enough. Promises on paper cannot keep us safe."
That warning of the limits to U.S. power is broadly the same message Obama wanted to deliver on climate change and @placeholder, which he focused on this week.