By the end of this century, the Chesapeake Bay could rise an additional 0.6 to 1.2 meters (two to four feet), according to an organization called CSSPAR (pronounced "see-spar"). CSSPAR, whose name stands for Chesapeake Sea Level Rise and Storm Surge: Public Awareness and Response, gathers information about sea-level rise on the Chesapeake. It does this work in partnership with organizations like the National Geographic Society.

Sea levels around the world are rising due to global warming, which is primarily caused by the burning of fossil fuels like coal and gasoline. As average temperatures rise, polar ice from both Greenland and Antarctica is melting into the world's oceans. Historically, oceans rise at an average rate of 12.7 to 20.3 centimeters (five to eight inches) every 100 years.

Chesapeake Bay's water level is rising at an even faster rate than average, however, because the land underneath the bay is sinking. During the last ice age, glaciers pushed the land surrounding the Chesapeake Bay upward. After the glaciers melted, the land slowly retreated to its original position through a process called land subsidence. As the land sinks, the water in the Chesapeake Bay rises. Land subsidence contributes to about half of the Chesapeake region's observed sea-level rise.

Already near Sea Level

Much of the land in the Chesapeake region already lies very near sea level. For that reason, even a small rise would have a major effect.

National Geographic researcher Sean O'Connor created maps for CSSPAR that illustrate the predicted effects of sea-level rise on the Chesapeake Bay. If sea-level rise continues at its current rate, the bay would invade the land for miles in some places. It would destroy approximately 167,000 acres of marshland by the year 2100. Around 1.9 million homes would be destroyed.

The Chesapeake Bay is a precious American resource. It is "the nation's estuary," O'Connor said. An estuary is an ecosystem where fresh river water pours into the salty ocean, creating a delicate, marshy habitat. Hundreds of rivers empty into the Chesapeake estuary along the shorelines of six states. Around 18 million people live in the Chesapeake region. The U.S. capital, Washington, D.C., sits upon the Chesapeake watershed.

Sea-level rise in the Chesapeake Bay will destroy the wetland habitats of many birds, fish, shellfish and plants. Human populations and structures are also at risk. In many low-lying areas, farms and homes will have to be relocated as the bay floods the land. Roads, bridges and buildings will need to be removed and rebuilt, as will sewage, draining and other utility systems. As the sea creeps inland, rebuilding major metropolitan areas such as Baltimore will be extremely costly.

Acute Effects of Storms on the Region

A higher water level in the bay means stronger storm surges and higher floodwaters. A storm surge is a sudden rise in sea level caused by a major storm.

The warm waters of the Atlantic Ocean can thrust powerful tropical storms and hurricanes into the U.S. East Coast, and the low-lying Chesapeake region is at risk when one of these storms hits. The region's cities will be flooded as the ocean surges inland.

Global warming is not only causing a rise in sea levels, it is also creating more extreme weather conditions. As global warming intensifies, storms will become more powerful and more frequent.

More intense storm surges are already hitting the Chesapeake. Scientists from CSSPAR compared a 1933 storm to a 2003 storm, Hurricane Isabel. The storms hit the same coastal area with approximately equal force. However, the storm surge from Isabel was higher than the one in 1933.

Hurricane Isabel's surge was measured at 1.8 to 2.4 meters (six to eight feet) above the normal water levels of the Chesapeake Bay. The same was seen in the Maryland cities of Baltimore and Annapolis.

The deadly storm ripped apart buildings and wetlands. It caused millions of dollars in damage, downed thousands of trees and cut off electricity to two million people. Some did not regain power for a week.

CSSPAR scientists modeled the effects of a storm like Hurricane Isabel hitting the Chesapeake 70 years in the future. By that point, the sea will be about 0.6 meters (two feet) higher than it is now.

The results of their modeling showed that flooding would be worse than anything ever seen before. For instance, Isabel caused an approximately 1.4-meter-high (eight-foot-high) flood in Old Town Alexandria, Virginia. Add another 0.6 meters (two feet) to the bay, and the flood would be three meters (10 feet) high. In the nation's capital, several national monuments, navy yards and crucial highways would be covered in deep, muddy water. The resort area of Virginia Beach, Virginia, would be heavily damaged. Homes, hotels, roads and islands would be flooded and muddy.

Technology will Help Spread Information

Though storms will become more powerful and violent, O'Connor hopes improved technology will reduce human deaths when future storms hit. Such technology can make real-time predictions about the effects of storm surges.

Satellite imagery and the use of global positioning system (GPS) coordinates can help people understand how strong a surge will be and how long it will last. Damage to homes, businesses and transportation systems could be reduced.

"If we continue to improve these models, we won't necessarily see the same impact on humans [as in past storms] because we would have a better system for educating people," O'Connor said. In other words, this storm-prediction technology could save lives.