In a recent visit to Prime Hook National Wildlife Refuge, Tom Alvarez was shocked to see how much beach and marsh have been lost. The U.S. Fish and Wildlife Service staffer from Massachusetts had not been to the area for more than 30 years.

Gradual change could accelerate if current predictions of sea-level rise come to fruition. Some scientists predict that in as little as 75 to 90 years, large sections of the refuge – which today serves as a critical stopover point for an estimated 1 million migrating birds each year – could be under water.

If Delaware Bay water rises one-eighth inch per year, by 2100, sea-level rise would essentially wipe out more than half of the marshland, according to a model developed by the U.S. Fish and Wildlife Service, known as the Sea Level Affecting Marshes Model (SLAMM).

Alvarez said the threat to Prime Hook and Bombay Hook refuges have placed them among his agency’s top five areas of concern nationally for sea-level rise and climate-change implications.

Today, the refuge is 15 percent open water, 47 percent marshland, and the remaining 38 percent is uplands and forested wetlands.

A rise of 1.6 feet would leave the refuge about 65 percent open water and 21 percent marshland, leaving only about 14 percent as uplands and forested wetlands.

State agencies, scientists and environmental groups are also sounding the alarm on the future of the refuge,

Danielle Kreeger, science coordinator for the Partnership for the Delaware Estuary, said a 1.6-foot rise is a very conservative estimate. Scientists now concur the accepted rate of global sea-level rise is about 3 feet by 2100, she said. “Locally, whatever that number is, it will rise much more,” she said, noting it could increase by as much as another foot.

“If you ask me how bad it’s going to be, I answer it’s going to be pretty bad,” she said. “We are going to lose a lot of wetlands, and there is no way around it.”

David Carter, environmental program manager with Delaware Coastal Programs who is at the forefront of sea-level rise work in Delaware, said there are scientific reasons to believe sea-level rise will accelerate during the next century and exceed the historical rise of 1 foot per century.

“If it does occur, the risk of bad consequences is very high, and we are planning for that,” he said.

A bleak picture

A rise in coastal flooding and washouts along the Delaware Bay coast, loss of coastal wetlands, and loss of sand and dunes along the ocean coast could be evidence of the effects of sea-level rise already occurring on the Delaware coastline.

Historical data show the sea rises and falls over the centuries; it has risen about 1 foot over the past century along the Cape Region coast. While not all scientists agree, a number of scientists are predicting sea-level rise will escalate during this century and could rise as much 1.5 to 3 feet along the Delaware and New Jersey coastlines.

The Intergovernmental Panel on Climate Change (IPCC) is somewhat more conservative, estimating that in the next century, sea levels worldwide will increase from 6 inches to 2 feet, but the amount of sea-level rise will vary by region. Because the low-lying Delaware coastline is so vulnerable to rising seas, especially the Delaware Bay coastline, the University of Delaware has been in the forefront of sea-level rise study. A 2007 study by the College of Earth, Ocean and Environment concluded sea-level rise could range from 2 to 5 feet by the end of the century as small portions of Greenland, Antarctica and glaciers melt.

Generally, reasons for the rise are tied to thermal expansion of the planet’s oceans and the melting of ice at the poles.

The University of Delaware study paints a dark picture based on current climate trends. With large-scale ice melting, due to increased carbon emissions, over the next few centuries the rise could be from 21 feet to 41 feet.

Using the lower estimate, most Delaware Bay beaches would be under water, while using the higher estimate, most of Sussex County would be under water.

“We conclude from these data that to prevent these amounts of sea-level rise, we must reduce human carbon emissions within a few decades, not a century or more,” the study concludes.

Do impoundments increase loss?

The Nature Conservancy is also serious about climate change and resulting sea-level rise.

The conservancy recently reported the Mid-Atlantic region has become slightly warmer by about 1 degree and much wetter, by 10 percent, since 1895. Climate models show that warming in the United States will be above the global average and could increase the annual number of 90-degree days in the state by as much as 250 percent by the end of the century.

Climate change contributes to sea-level rise, but it also affects the fishery, forests, tourism and public health, according to the conservancy’s report.

The conservancy estimates 20 to 70 percent of the intertidal shorebird habitat in the Delaware Bay could be destroyed before the end of the century. The bay is home to the second largest spring migration of shorebirds in the Western Hemisphere with more than 1 million birds using the areas around Prime Hook and Bombay Hook refuges as stopover points.

Habitat loss from sea-level rise could disrupt seasonal patterns affecting shorebird food sources. The report also concludes that sea-level rise and increased storm surges could severely degrade or destroy coastal barrier beaches.

Carter said there are real concerns for the refuges over the next 25 years. Manmade water-control devices are preventing sediment from washing toward the sea, a process that provides crucial building material for the marshes.

“How long can we hold the line and maintain the ditches?” he asked. “We need to look at the impoundments before we get a real serious problem.” Kreeger said the coastal bay region more susceptible to climate change because not only is bay water rising, but also coastal land is sinking – marshes and wetlands are not rebuilding to keep pace with sea-level rise.

Carter, of Delaware Coastal Programs, says now is the time to start planning for increased sea-level rise, in case the worst-case scenario should occur and sea level rises in excess of 1.5 feet. What is considered flooding today in some low-lying coastal areas could easily be the high-tide line in a few decades, he said. “With advanced planning we can help to keep life in these areas somewhat normal, or at least at a new normal. We can help these areas become less susceptible to storm damage and sea-level rise,” he said.

Carter said it’s important for policy makers to be well informed long before the lasting effects of sea-level rise and future storms are felt. He said the last wake-up call, the Storm of 1962, should serve as a reminder how vulnerable the area is.

“The big difference now is that where there was natural migration of wetlands we now have people, infrastructure and economic drivers. Those really change our options,” Carter said.

He said the goal is not to retreat from vulnerable coastal areas like Prime Hook Refuge, but to stay as long as possible. “But we recognize that’s not forever,” he said.

Alvarez, the U.S. Fish and Wildlife Service Northeast Region public affairs specialist, said the service is looking at the bigger picture of climate change. “It’s not necessarily how we can change it, but how to cope with it in relationship to wildlife and resource conservation,” he said.

The service administers all national wildlife refuges.

Currently, five miles of Atlantic beachfront is protected while 17 miles, mostly in state parks, is permitted to migrate naturally, Carter said.

He said those same decisions would have to be made concerning other coastal areas along the Delaware Bay. “Do we protect or let nature take its course?” he asked. “There are tough issues. This is a different kind of planning.” He said the status quo should be maintained as long as economically feasible. “But there may come a time it’s not cost effective,” he said.

Policy changes may be needed at the state level on the issuance of permits and road and other infrastructure construction. He said people who live in the vulnerable areas would have to be more aware of weather conditions. He said the University of Delaware is setting up an early-warning system to help residents evacuate early. “Our biggest fear is that they can’t get out,” he said.

“We also want public input for what is acceptable; where to hold our ground,” Kreeger said.

The Partnership for the Delaware Estuary is working to prioritize the most vulnerable marsh areas and provide a path forward to protect them. “But there is always going to be limited dollars so we have to be very strategic,” she said.

Any agency working on the issue will face the same issue in tight economic times.

Alvarez, who is based in Hadley, Mass., said within his agency, Prime Hook and Bombay Hook refuges are among the top five areas of concern nationally for sea-level rise and other climate-change implications.

Next: Scientists know marshes and wetlands in and around Prime Hook Refuge are disappearing, but they are not 100 percent sure of the reason.