The Chesapeake Bay is rising. Since Captain John Smith settled what is now the U.S. city of Jamestown, Virginia, near the shores of the Chesapeake in the 1600s, the bay has risen 0.9 meters (three feet). This rise in sea level has drowned many islands where small fishing communities once thrived.

By the end of this century, the Chesapeake could rise an additional 0.6 meters (two feet), according to moderate estimates reported by an organization called CSSPAR (pronounced “see-spar”), which stands for Chesapeake Sea Level Rise and Storm Surge: Public Awareness and Response. This partnership, which includes the National Geographic Society, was started by the Conservation Fund. CSSPAR works to gather and distribute information about sea level rise and intensified storm surges on the Chesapeake Bay.

Polar ice from both Greenland and Antarctica is melting into the world’s oceans. Oceans rise at an average rate of six inches every 100 years.

Sea level in the Chesapeake Bay rises at a faster rate than average 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. Melting ice causes the remainder.

The Nation’s Estuary

Since so much of the land in the Chesapeake region already lies very near sea level, even a small rise would have a huge impact.

“If an area of land is less than 0.6 meters (two feet) above sea level, and connected to a stream or inlet that is part of the bay, than that area is at risk for what we call ‘inundation’ by rising sea,” explained Sean O’Connor, a National Geographic Society cartographic researcher.

O’Connor created maps for CSSPAR that illustrate the predicted effects of sea level rise on the Chesapeake Bay. If sea level rise continues on its current path, the bay would invade the land for miles in some places, destroying 167,000 acres of marshland and three million people’s homes by the year 2100.

The Chesapeake Bay is a precious American resource, “the nation’s estuary,” as O’Connor describes it.

The U.S. capital, Washington, D.C., sits upon the Chesapeake watershed. 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 20 million people live in the Chesapeake region.

“The shorelines of the Chesapeake are flanked with important human infrastructure, like the naval facilities at Norfolk, Virginia, or the bustling commercial, residential, and tourist districts of Baltimore, Maryland. And much more area is graced with low-lying wetlands, cypress forests and tidal marshes that are home to countless species of fish, mammals, birds and more. But yet, the estuary finds itself under constant threat of dying out from too much pollution, from overharvesting of species and now from climate change,” O’Connor said.

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 restructured, as will sewage, draining and other utility systems. As the sea creeps inland, rebuilding the infrastructure of major metropolitan areas such as Baltimore will be an extremely costly endeavor.

Storms are Brewing

The more acute devastation of sea level rise will threaten the area when storms hit. The region’s cities will be flooded as the ocean surges inland.

A higher water level in the bay means stronger storm surges and higher floodwaters. 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 vulnerable when one of these storms hits. As global warming intensifies, these storms will become more powerful and more frequent.

More intense storm surges are already hitting the Chesapeake. Scientists from CSSPAR compared data from a 1933 storm (the Chesapeake-Potomac Hurricane) to data from a 2003 storm, Hurricane Isabel. The storms hit the same coastal area with approximately equal force. However, the storm surge from Isabel was about 0.3 meters (one foot) higher than the one in 1933.

Hurricane Isabel's surge was measured at 0.9 to 1.5 meters (three to five feet) above the normal water levels of the Chesapeake Bay. In the Maryland cities of Baltimore and Annapolis, water was 1.8 to 2.4 meters (six to eight feet) higher than normal.

The deadly storm ripped apart buildings and wetlands, caused millions of dollars in damage, downed thousands of trees, and cut off electricity to half a million people for a week.

The CSSPAR scientists modeled the impact of a storm like Hurricane Isabel hitting the Chesapeake 70 years in the future, when the sea will be about 0.6 meters (two feet) higher than it is now. The Chesapeake Bay Observing System collected data from shore and marine-based weather stations, and the Virginia Institute of Marine Science used this data to simulate and predict future storm surges in the Chesapeake region.

The results of their modeling showed that flooding would be unprecedented. For instance, Isabel caused an 2.4-meter (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 economically damaged. Homes, hotels, roads, and islands would be flooded and muddy.

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 impact of storm surges.

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