With about half the world’s population dwelling within 100 kilometers (60 mi) of a coast, few changes wrought by a warming climate will have as great an impact on so many as sea-level rise.
If the commonly accepted prediction of a one-meter (3.28 ft) rise by the end of the century occurs, entire island nations may be lost and millions of people forced to adapt or relocate.
At the University of Delaware, researchers are developing monitoring and modeling tools and pursuing ethical studies to aid policy makers locally and internationally in making the tough decisions driven by the rising tide.
Delaware lies in one of the most vulnerable areas of the United States when it comes to sea-level rise. With the lowest mean elevation of any state in the nation, much of Delaware is already prone to flooding from coastal storms, and any amount of sea-level rise would be expected to exacerbate this problem.
After a major storm in May 2008 left one person dead and many homeless along the Delaware Bay coast of Kent County, the Delaware Department of Natural Resources and Environmental Control turned to the Delaware Geological Survey (DGS) and the Delaware Environmental Observing System (DEOS), both based at UD, for help in establishing a coastal flood monitoring system.
DEOS consists of 40 observation platforms around the state that monitor weather, atmospheric and near-surface soil conditions and makes the data available to users in real time. Through the DEOS Alerts System, subscribers can request notification when parameters of their choice cross certain thresholds.
“Delaware has probably the best instrumented and observed environment of any
state in the country,” says Dan Leathers, co-director of DEOS and professor in the Department of
Geography. “Our station density is much greater than other states that have more area to
DEOS personnel worked with DGS colleagues to put together a system that uses tidal surge prediction data from the National Weather Service in a statistical model that outputs potential inundation levels for a given community in a web-based mapping and data visualization system.
“The system can predict tide heights about five days in advance and warn community leaders and first responders of an impending flood event,” Leathers says. “Our website provides forecasts, maps to show inundated areas, and cross-sections of evacuation routes so that people will know how deep water will likely be on the roads.”
Learn more at www.deos.udel.edu.
How will rising sea level affect the quality of ground-water and surface water that millions of people rely on for drinking? In a study funded by the World Bank, Holly Michael, assistant professor in the Department of Geological Sciences, is looking at water resources in Bangladesh, a low-lying and densely populated nation where an estimated 15 million people over 17,000 square kilometers (6,563 sq mi) could be displaced by a one-meter rise in sea level.
As Michael explains, saltwater can intrude into fresh-water resources in several ways, most notably by overtopping surface and near-surface waters as sea level and storm surges reach farther and farther upland, and by lateral intrusion into deeper groundwater beneath coastal lands.
Using water quality and rock formation data from 20,000 coastal wells collected from the government of Bangladesh and international aid agencies, Michael has developed a simulation model based on past changes in sea level that predicts how the freshwater-saltwater interface in coastal groundwater will respond to rising sea level, as well as how fast those changes could be expected to occur.
“What our model indicates is that overtopping is a more immediate threat to water
resources in Bangladesh because it will happen faster, on the order of decades
to a couple hundred years,” Michael says. “Lateral intrusion at the level of the deeper wells will likely happen at a much
slower pace, perhaps over thousands of years. With similar data, we can extend
these methodologies to other locations, including Delaware.”
Another potential risk of sea-level rise is the inundation of industrial coastal areas that harbor toxic chemicals in the soil. By changing the chemistry around soil particles, which then become aquatic sediments, saltwater may help release these contaminants from the soil and make them more available to organisms that swim in or drink the water or eat other organisms that do.
Dominic Di Toro, Edward C. Davis Professor of Civil and Environmental Engineering and member of the National Academy of Engineering, specializes in analyzing the behavior and toxicity of chemicals such as PCBs in aquatic sediments and in the water column. He notes that toxins can behave quite differently depending on the type of sediment.
Di Toro’s models enable him to predict what the resulting levels of contaminants would be in the water if a site were flooded with seawater. He can then go on to predict the toxicity of these chemicals for organisms. His methods have been used to analyze sediments affected by the recent Gulf oil spill.
“By combining information about what is present in the soil, the physical
properties of the tides and currents, and the chemistry of the water, we can
provide risk assessments to the policy people whose job is to manage the risk,” Di Toro says. “For example, they may consider dredging and relocating toxic sediments. The
question for them becomes, ‘Is it worth it?’”
Nowhere will the effects of sea-level rise be felt like the world’s 51 small island nations. On these small, low-lying land masses and coral atolls, facing sea-level rise is a matter of survival — and is already a reality.
Countries such as Kiribati in the South Pacific are experiencing major erosion and damages to infrastructure and property due to higher than usual tides and storm surges. Their potable water supplies and farmland are being contaminated by saltwater.
Kiribati and places like it may one day even become completely inundated. The government of the Maldives announced it is setting aside tourism revenue to purchase a new homeland if necessary.
“Small island states are the most threatened by climate change and they typically lack sufficient resources to carry out needed adaptation and mitigation measures,” says Biliana Cicin-Sain, co-chair of the UD-housed Global Forum on Oceans, Coasts, and Islands.
Cicin-Sain and her colleagues at the Global Forum are working to give the threatened nations a stronger voice in the development of international climate change policy.
“We provide vital forums for high-level leaders and experts to address the major policy issues affecting oceans, and especially small-island developing nations,” says Cicin-Sain, who also is the director of UD’s Gerard J. Mangone Center for Marine Policy.
For example, Cicin-Sain and her team drafted sets of policy briefs to provide information and perspectives on oceans and climate change for participants at the May 2009 World Ocean Conference in Manado, Indonesia, as well as those involved in the climate negotiations of the United Nations Framework Convention on Climate Change (UNFCCC).
The Global Forum also co-organized Oceans Day at the December 2009 UNFCCC meeting in Copenhagen. That event brought together 320 leaders from 40 countries, representing governments, U.N. agencies, non-governmental organizations, the scientific community and industry to focus on the direct link between climate change, ocean health and human well-being.
“Oceans Day participants agreed that there is a need to craft an integrated oceans and coasts program within the UNFCCC by 2013 emphasizing, for example, that there should be sufficient funding to support island communities needing to adapt to climate change,” says Cicin-Sain, who is planning the event for the 2010 UNFCCC meeting in Cancún, Mexico.
The island nations could certainly use the help. Their economies and livelihoods — fishing, tourism, and other activities that rely on a healthy sea — are already threatened by other effects of climate change. For instance, warming ocean temperatures and other related impacts threaten sensitive coral reefs, which support marine ecosystems.
And paradoxically, these countries collectively generate less than 1.3 percent of global carbon dioxide emissions. Yet they face the threat of their homelands disappearing entirely as a result of climate change while receiving limited attention at international climate negotiations.
“This effect, known as the ‘Climate Divide,’ has been a major theme in climate change policy,” Cicin-Sain notes.
With problems such as flooding, contamination of drinking water and loss of land impending, and with resources for dealing with these issues limited, government officials will face significant ethical dilemmas. Which areas and which citizens will receive help in adapting to the changes driven by sea-level rise? Will resources be used to remediate habitat loss or to protect personal property?
The Delaware Experimental Program to Stimulate Competitive Research (EPSCoR), supported by the National Science Foundation, has provided seed funding for two studies to explore these issues.
Kevin Adkin received his bachelor’s degree in geography at UD and then entered UD’s School of Urban Affairs and Public Policy for graduate study. He is using his seed grant to support his dissertation work, which focuses specifically on the needs of the Southbridge community — one of Wilmington’s poorest neighborhoods with a number of brownfields located nearby — in the eventuality of sea-level rise.
In addition, Matt Oliver, assistant professor of oceanography, and a colleague from Princeton University, are using the Biblical parable of the Good Samaritan as a basis for exploring the obligation of scientists and engineers to use their knowledge to help people who are most vulnerable to sea-level rise.
Even in a worst-case scenario, sea-level rise is likely to occur at a gradual pace that should give communities time to plan a response. As Chaucer noted, however, “Time and tide wait for no man.” UD researchers are determined to help their state and other communities around the world prepare wisely for the future.