Ghost forests created by the submergence of low-lying land are one of the most striking indicators of climate change along the Atlantic coast of North America. The earliest descriptions of ghost forests date back to 1910.
Jennifer Walker, who recently earned her Ph.D. in oceanography at Rutgers says that the pace of sea-level rise first quickened in the late 19th century after the Industrial Revolution, and then sped up again in recent decades. It’s now rising faster than at any point in the past several thousand years.
Today, the water is rising as much as 5 millimeters (0.,20 inches) per year in some places, well above the global average of 3.1 millimeters, driven by profound environmental shifts that include climate change.
And as sea levels rise, more and more saltwater encroaches on the land. Along the world’s coasts and estuaries, invading seawater advances and overtakes the freshwater that deciduous trees rely upon for sustenance. Basically, the saltwater poisons the trees.
A combination of factors involved
Researchers agree that the rapid increase in ghost forests represents a dramatic visual picture of environmental changes along coastal plains located at or near sea level. However, taking into account the historical perspective, humans have helped to create the ghost forests.
No, it was not done on purpose but was simply the end result of progress, worldwide population growth, expansion in the U.S., more frequent droughts that reduce the amount of fresh water available and the sinking of coastal lands that began after the last Ice Age.
The Chesapeake Bay, the country’s largest estuary system, is an excellent example of the sea’s rapid advance, said Keryn Gedan, a wetland ecologist at George Washington University. People living along the Eastern Shore are being hit by rapidly rising sea levels, in part – because of the increased melting of Greenland’s ice cover.
The freshwater flowing into the Atlantic Ocean may be slowing down the Gulf Stream, which flows northward up the coast, creating what scientists call a pileup of water along the East Coast, elevating sea levels locally. Residents living in cities and communities along the shores of the bay face flooding streets frequently.
Flooding is having a severe impact on many local communities, as well as cities like Norfolk and Newport News in Virginia. Damages from the recurrent floods are costing millions of dollars every year.
Subsidence, the sinking of the Earth’s crust – is another problem to add to the mix in the Chesapeake Bay region. While most of the sinking is due to geological processes, the effects of climate change, such as more frequent tropical cyclones and extreme storms have added to the risks.
Because of the extraordinary speed at which the water is rising here, Dr. Gedan said, “I think of this area as a window into the future for the rest of the world.”
The Mississippi Delta region of Louisiana
The Mississippi Delta region of Louisiana is undergoing changes due to rising waters, the sinking of Earth’s crust, and sediments compacting along the Mississippi River. The huge area is 200 miles long and 87 miles at its widest part. Originally covered in hardwood forest across the bottomlands, it was developed as one of the richest cotton-growing areas in the nation before the American Civil War.
This region is part of an alluvial plain, created by regular flooding of the Mississippi and Yazoo rivers over thousands of years. However, in modern times, this region of rich, fertile soil has changed. Between 1974 and 1990 the land loss rate in the Mississippi River Delta Basin averaged 1,072 acres per year or 1.69 percent of existing land area.
This loss is the result of compaction, subsidence, hurricanes, tidal erosion, sea-level rise, and human activities. The loss has been aggravated by the maintenance of navigation channels and the construction of canals for mineral exploration. The region has lost about 113,300 acres in the past 60 years.
Many areas of the Louisiana coast suffer from a lack of abundant freshwater and sediment found in the Mississippi River. Since the river is no longer free to alter its course and leave its banks to inundate vast coastal areas, the effects of human and natural forces that promote wetland deterioration are compounded. And this is seen all along the Louisiana coast today.
