We'll see permanent refugee camps for flood victims. Their homes are innundated every year. We may see these in the US within the next couple of decades.
At a time when climate change is putting stress on all of our resources, diseases will flourish and to add insult to injury we are heading into a post-antibiotic era as the bugs become resistant to them.
The Antibiotics Crisis (video)
So put these to things together and what do you get? People in crowded and unsantitary conditions will be vulnerable to diseases we can no longer treat. This may result in a heartbreaking mortality rate for those who have nowhere else to go.