Answer:
Sea level rise - if temperatures continue to rise at a fast pace like they do currently, not only the artic will continue to melt, but other glacials, particularly Greenland, could melt as well.
A sea level rise of 5m would flood vast areas of major cities in the world like Miami, New York or Amsterdam. In fact, over half of the Netherlands would be underwater in such situation. This would affect millions of people around the world, leaving them potentially homeless, and causing unwated migrations.
Desertification - Climate change could raise temperatures, disrupt precipitation patterns, and accelerate de desertification of vast areas of the world, putting the production of food at risk. A particularly dramatic case in the Sahel, in Western Africa.
The Sahel is the region that transitions from the Sahara Desert, to the tropical rainforests of Western Africa. If the Sahel continues to expand and becomes a desert, the survival of millions of people in countries like Chad, Mauritania, and Nigeria could be at risk.