Sea Level

Scientists warn that the biggest danger from global warming is raising sea level through a combination of increased water from glacier melting and warmer water temperatures causing expansion. Sea level has risen 4 to 10 inches this past century and is projected to rise up to 3 feet by 2100. For every foot of sea level rise we can expect about 100 feet of coastal flooding.

Today, about 25% of the world’s population lives within 62 miles (100 kilometers) of a shoreline, and this figure is likely to increase to 50% over the next twenty five years as people flock to coastal cities. Thirteen of the world’s 20 largest cities are now located on a coast. As sea levels go up we can expect to see increasingly negative impacts on coastal areas. Storms will wreck a greater number of coastal properties, low-lying areas will be flooded, beaches eroded, wetland ecosystems and fish and wildlife habitats destroyed and saltwater will contaminate aquifers threatening human water supplies.

The U.S. Environmental Protection Agency (EPA) estimates that a two foot rise in sea level would eliminate approximately 10,000 square miles of land, an area equal to the size of Massachusetts and Delaware combined. The Federal Emergency Management Agency (FEMA) estimates that about 25 percent of all buildings within 500 feet of the U.S. coastline will be taken by erosion in the next 60 years. The wild card in all this is abrupt sea level rise due to rapid melting of the Greenland ice Sheet.

Make your own map.

Using computer models, scientists at the Environmental Studies Laboratory at the University of Arizona have created a series of maps that show areas susceptible to rises in sea level.

Results indicate that the earth will be warm enough in less than 150 years (assuming no reduction in greenhouse gas emissions) to melt the Greenland Ice Cap. This change could also lead to four to six meters of sea level rise at rates of up to two to five centimeters per year.

Environmental Studies Laboratory, University of Arizona.

1 meter = 3.28 feet
6 meters = 19.68 feet

USA: Louisiana +1m
Weiss and Overpeck, The University of Arizona

USA: Louisiana +6m
Weiss and Overpeck, The University of Arizona