One effect of increased temperatures is a rise in sea level. NOAA data have shown that sea level is rising at an increasing rate. Since most humans live on coasts, rising water levels can have potentially large impacts on human societies. While sea levels changed little from 0 until 1900, sea levels began to climb in the 20th century.
The two major causes of global sea-level rise are the loss of land-based ice and thermal expansion. When land-based ice melts into the oceans due to increased temperatures and the albedo positive feedback loop, it causes more water to flow into the oceans, increasing sea level. Thermal expansion is the increase in volume of water as it increases in temperature. Global sea level rise is a product of both of these processes.