Sea level rise is primarily caused by two factors related to global warming: the added water from melting ice sheets and glaciers and the expansion of seawater as it warms. Satellite monitoring indicates that Antarctica is losing ice mass (melting) at an average rate of about 150 billion tons per year - 12 trillion metric tons since 1997 - and Greenland is losing about 280 billion tons per year. Meltwater coming from these ice sheets has been responsible for about one-third of the global average rise in sea level since 1993.
By the turn of the next century, global sea levels will have risen by up to four feet, potentially turning the hundreds of millions of people living in coastal regions into refugees.
