Today, DFM News begins a five part series on the potential impact of sea level rise in Delaware. Part one offers an overview of the issue - including what Delaware's Department of Natural Resources and Environmental Control (DNREC) has found as it completes an assessment of the state's vulnerability for a report due this fall. Subsequent parts will look at the issue county-by-county and the effort to develop long term solutions.
[caption id="attachment_15956" align="alignright" width="300" caption="Waters of the Delaware Bay approach the dunes behind the Children's House in Lewes, Del. (Click to enlarge)."]
Melting glaciers; retreating coastlines; ferocious storms; eroding beaches.
It’s a familiar disaster scenario promulgated by global climate change scientists and opposed by skeptics but increasingly adopted by national and local governments seeking to protect people and property from the severe damage threatened by rising sea levels.
The projections are based on estimates that the world’s overall sea level will rise by between 0.5 meter and 2.15 meters by 2100, and that the rate of increase seen over the last century will soar in coming decades as populations, economies and greenhouse gas emissions grow, according to recent studies by national and international bodies.
The International Panel on Climate Change projected in 2007 that global sea levels will rise between 7 and 23 inches over the next century. But that estimate is now seen as too low because it doesn’t include the effects of melting ice from West Antarctica and Greenland.
The panel said it’s “virtually certain” that beaches and barrier islands on the mid-Atlantic coast will erode faster as sea level rises, and it noted that some tidal wetlands are already covered with water because of sea-level rise.
Delaware and other mid-Atlantic states are likely to see oceans rise more sharply than the global average because the land is sinking as the waters rise, scientists believe. Because of land subsidence, the state’s annual sea-level rise of 3.3 mm a year is almost twice the global average of 1.7 mm.
The state’s Department of Natural Resources and Environmental Control (DNREC) has projected sea-level rises of 0.5, 1.0 and 1.5 meters by 2100, depending on the risk sensitivity of a location.
[caption id="attachment_15944" align="alignleft" width="200" caption="What could rising sea levels mean where you live? Click the image above to see DNREC's interactive Sea Level Rise Inundation maps, which show the impact various sea level rise scenarios may have on Delaware’s waterways and the land that surrounds them (External Link)"]
A wastewater treatment plant, for example, is an expensive piece of public infrastructure and so would probably be built to withstand 1.5 meters of sea-level rise, said Susan Love, a resource planner at Delaware Coastal Programs, a division of DNREC. Builders of a less expensive project like a pier with a limited lifespan could assume that seas will rise by only 0.5 meter.
Even the lower estimates would cause widespread flooding, inundating low-lying areas such as barrier islands, damaging infrastructure such as roads and power plants, and forcing salt water into the aquifers that supply drinking water.
Even if you believe the predictions, all of the changes aren’t expected to take place for about another 100 years, and for most people, a sea-level rise that’s measured in a few millimeters per year is neither perceptible nor very worrying.
But DNREC isn’t waiting to find out whether sea-level rise will cause just local flooding or a statewide catastrophe.
Officials are working on an assessment of the state’s vulnerability to rising sea levels and will issue their findings in a report expected in the fall.
“Because of its location and link to the coast, Delaware is particularly vulnerable to the effects of rising sea levels,” the department said in an advisory on the issue. The effects range from increased flooding of homes during storms to more shoreline erosion and the inundation of tidal wetlands, it warned.
The state is “very likely” to feel impacts from sea-level rise in coming decades, DNREC said, and the rising waters are expected to do a lot more than displace shorebirds from coastal marshes.
A one-meter rise in sea level over the next 100 years – the midpoint of three scenarios in DNREC’s plans – would cause the loss of 3 percent, or more than 11,000 acres, of Delaware’s prime farmland, according to preliminary results from the report. If sea level rises 1.5 meters, 4 percent of prime farmland would be inundated statewide, rising to 6 percent in Sussex County.
Existing farmland could also be ruined by sea water invading rivers and streams whose fresh water is currently used for irrigation, and by sea water advancing further inland than the point at which cropland currently meets the salty zone.
Higher sea levels would also affect crucial transportation services including airports, bus routes, railroads and the economically important Port of Wilmington, the report is expected to say.
Among vital installations to be considered in the report are power stations, wastewater treatment plants, and telephone switching stations.
The ability of emergency services to respond to sea flooding would be hit because some of the services would themselves be inundated, the report is expected to say. Statewide, 7 percent of ambulance and paramedic stations would be under water if sea level rose by 1 meter. The worst affected area would be Kent County where 13 percent of those stations would be inundated.
Higher water levels are already causing some loss of farmland, according to David Carter, an environmental program manager in DNREC’s Coastal Programs. He cited reports from farmers and hunters of changing coastlines, flooded field edges, and tilling lines being moved away from rising waters.
“These are problems that are very real right now,” Carter said. “They will get a whole lot worse if seas continue to rise.”
[caption id="attachment_15970" align="alignright" width="300" caption="Aging dikes (right) protect the shore along the banks of Battery Park in New Castle, Del. (Click to enlarge)."]
Even if the generally accepted sea-level rise scenarios turn out to be unduly pessimistic, the state will still be well-served by planning for them, Carter argued. “If it doesn’t accelerate, the worst we’ve done is to spend money to protect from storm surges,” he said.
Despite the dire warnings, DNREC’s work on sea-level rise attracts skeptics such as Rich Collins, executive director of the Positive Growth Alliance, a Harbeson-based group that promotes free enterprise and opposes government intervention.
Collins, who is among a group of business owners, city officials and citizens’ groups that make up DNREC’s Sea Level Rise Advisory Committee, argues that the agency’s efforts to prepare for sea-level rise is an unwarranted attempt to control people’s response to a phenomenon that may not even happen.
“We never put an off switch on any of these agencies,” he said.
Collins said recent satellite evidence on sea-level rise does not support projections used by DNREC or international agencies, and even if those forecasts turn out to be true, individuals should not be forced to respond by following government edicts.
“People who buy beach houses know that they are running the risk that they will be washed away in the next storm,” he said. “They choose to live with it.”
Although Collins admits his skeptical stance puts him in a minority on the committee, he said he has persuaded the panel to consider, for example, whether the state has the planning authority that it claims, or whether that belongs to county and municipal governments.
If the sea-level rise scenarios play out, businesses and individuals will have to make changes such as avoiding building seafront houses. But before that happens, persuading people to take the issue seriously could be a challenge, judging by a 2010 survey showing little public concern over the issue.
The survey for DNREC of 1,505 residents found sea-level rise was at the bottom of their top 10 list of national issues. Only 30 percent said they were “very concerned” about sea-level rise, behind 75 percent who rated the economy the most pressing issue. Sea-level rise was also bottom-ranked among environmental issues, with only 32 percent of respondents saying they were “very concerned” about it.
However well the state plans for sea-level rise, it is likely to have to sacrifice some areas to the rising waters during coming decades because the cost of saving everything will be too great, Carter said.
“We are going to have to make some difficult decisions as to where we hold our ground and where we don’t,” he said.
Next in the Rising Threat series: A look at how one community in New Castle County is addressing the issue of rising sea levels.
