The only way so much human need is going to be addressed long term is for all of the developed world to work together. Only by coordinated effort can creative, integrated, new solutions be found and adopted.
The problem is two fold, of course. Not only are long term solutions required, the short term need must be addressed as well. In this must be considered the creation and maintenance of a global Migrant/Refugee support fund; perhaps by a trans national trade tax; at least for the near term. This fund could then make coordinated purchases of food and housing infrastructure in regional hubs to create a living environment for these people.
Long term, however, is going to take a great deal more imaginative thinking. This is why I have always felt that the creation of hydrogen production at sea could be a self funding creator of floating support cities. It may seem like a stretch now but where else but the oceans can we turn to for the creation of new habitable city states? And what better way than using the wind and sun in or near the equator to create a environmentally sound fuel?