Seas Rising

Ocean Shore at Point Reyes, California, H Graem © 2005

Sea-level rise from the melting of polar ice sheets would be a devastating impact of global warming upon life on earth. 

Projecting the extent of such a rise 200 years in the future is difficult, given the variables involved. However, each new scientific discovery points to an increased rate of glacier melt and consequent sea level rise.

By the year 2100, polar warming may reach levels similar to those of around 125,000 years ago. Sea level was about eight (8) meters above modern levels at that time. Both the Greenland Ice Sheet and portions of the Antarctic Ice Sheet may be vulnerable.

The record of past ice-sheet melting indicates that the rate of future melting and related sea-level rise could be faster than widely thought. A scenario contemplating a combination of melting from the Greenland ice sheet as well as that of West Antarctica could bring about a sea level rise of six (6) meters or more.

Changing coastlines worldwide due to alternative future sea level changes can be demonstrated through the internet. One site, flood.firetree.net enables the viewer to experiment and view the effect of alternative sea level rises around the planet. The University of Arizona's Department of Geosciences has a site showing the impact of sea level rise on some areas in the eastern USA. Climate Central created an interactive map comparing the potential impacts of sea level rise under different conditions for vulnerable areas around the earth.

The satellite images below demonstrate the potential impact on five (5) different coastal areas of a 6 meter (20 feet) rise in sea level. The scenario assumes a failure of leading industrial nations, such as the United States, and emerging industrial giants, such as India and China, to seriously reduce emissions of the "greenhouse gases" linked to global warming. 

Sources for changed shoreline were USGS map contour lines (in the case of the Bay Area), the University of Arizona, Climate Central, and Firetree.

                         Today                                                                         Future 

 

San Francisco Bay - The impact of a 6 meter sea level rise varies significantly among the cities along San Francisco Bay. San Francisco because it rises steeply from the Bay, except where historical bay fill has occurred, is little affected. Foster City, since it was built on bay fill, disappears completely. East Palo Alto, except for a possible narrow sliver along its western edge, also disappears. Alameda becomes a much smaller island and Richmond is split by a new strait connecting the southern and northern reaches of the Bay. The former Sacrament/San Joaquin Delta and surrounding portions of the Central Valley become a new bay or sea tentatively identified as Sacramento Bay. The cities of Tracy, Manteca, Stockton, and Sacramento would lie along the marshes bordering this new bay. More than half of Stockton would disappear beneath the waves.

Florida - Florida gets really devastated by the envisioned sea level change. All or the major part of most of its coastal cities sink beneath the waves. Miami ends up about 110 kilometers (70 miles) out in the ocean. Key West finds itself even further out to sea. Even inland Orlando is impacted by an arm of the sea.

Mississippi Delta - The Mississippi Delta and the Gulf Coast of the United States would be inundated by a 6 meter rise in sea level. The only way New Orleans could be saved is with a strong levee immediately surrounding the city which would become an island some 50 kilometers (30 miles) out into the Gulf.

Bohai and Yellow Seas - The most impacted areas of China would be around the Bohai Sea and the Yellow Sea coast to the south. This is the location of some of China's largest cities.

Ganges Delta - The Bay of Bengal along the coast of India and Bangladesh would be drastically affected by sea level rise - with the Ganges Delta and its population of millions most heavily impacted.