How Global Warming Raises Sea Levels

Higher sea levels are a sure sign of global warming. Why, you may ask? Well, melting glaciers and polar ice sheets add water to our oceans. Glaciers store water on land. When the humongous ice masses melt into ocean waters, it adds volume and water levels increase. In addition, water expands as it gets warmer. So as temps increase, the same amount of water takes up even more space. In turn, raising sea levels even higher.

Risks Multiply as Sea Levels Rise: Rising sea levels are a double whammy for the coastline. They not only flood the land, but higher ocean waves also erode more coastline. Those living on the coast face a variety of concerns: increased flood risk, more property damage and costly insurance rates. And think about this - higher insurance rates can also cost you the taxpayer! That's because the federal government subsidizes flood insurance for many coastal properties.

Trouble Nationwide: Over the 20th Century, the seas rose between 2 and 8 inches - 10 times the average rate over the last 3,000 years. This trend is alarming to say the least and threatens the nation's coastal communities where more than half of the US population resides. Other parts of the world are at risk as well. More frequent and extreme flooding due to sea-level rise threatens low-lying areas near the mouths of the Nile in Egypt, the Mekong in Vietnam and Cambodia and Ganes and Brahmaputra in Bangladesh and other rivers worldwide. Italy's famous sinking city of Venice - which is surrounded by water and whose ground underneath is subsiding like Louisiana's - is also vulnerable.

People in the scientific community predict sea levels will continue to increase as a result of man-made greenhouse gas pollution and could reach an additional 3.5 inches to 3 feet by the end of the century. This, coupled with the possibility that even higher rises could happen if the ice sheets on Greenland and Antarctica melt. A foot of higher water could destroy anywhere from 50 to 1,000 feet of horizontal shoreline in many parts of the United States - depending on the slope of the coastline and other factors.

If sea levels continue to rise, thousands of square miles of land in heavily populated areas such as the Eastern US may be lost in a century or two and flooding during storm surges will get worse. Construction of barriers like seawalls would be costly and - in some cases - pointless.