More like closed borders guarded by military presence, leading to indirect genocide of the people trying to get into Europe(From Africa). As the resources(food and freshwater) becomes scarce and the migrations becomes unbearable, people in western countries will have to decide us or them. Will Europe allow mass migration into their countries or will they close the borders and look the other way? All Countries and areas in the world between latitudes 40 degrees north and south will be affected earlier and far worse than those longer north and New Zealand and Patagonia in South America. Seing as these areas are barely self sufficient on their own today, being able to feed and house the rest of the world will be a monumental challenge.