Global Melting

The melting of land ice is already raising sea levels. In some fairly likely scenarios, oceans would rise by meters worldwide with devastating results. A sea level rise of just one metre would displace tens of millions of people in Bangladesh alone.  All of this melting ice could dilute the world's oceans – changing the salinity enough to hurt fish stocks and disrupt ocean circulation patterns globally.

Then there is the chance that melting ice will cause a feedback effect due to the fact that snow and ice reflect more sunlight than bare ground or water so less ice means more warming (which melts more ice, etc.).