The backbone of the heavily populated mid-Atlantic and its fishing and tourism industries faces ‘dead zone’ challenges that will only be exacerbated by the warmer and wetter climate scientists foresee.
As the largest estuary in the United States, the Chesapeake Bay is the life force of the mid-Atlantic’s lucrative fishing and tourism industries.
The Bay boasts diverse ecosystems and exceptional beauty, and is the source of tens of thousands of American jobs. But the health and vitality of the Bay are threatened by a dead zone — an oxygen desert — that seasonally can grow to 40 percent of its total area of 4,479 square miles. This ecological catastrophe is destroying the livelihoods of many watermen, killing the bounty of the Bay, and threatening public health — a situation that only will worsen if the climate becomes wetter.
Put simply, climate change will make a bad situation much worse.
A dead zone is an aquatic area devoid of sufficient dissolved oxygen to support life. It is caused by a process known as eutrophication, whereby nutrient pollution stimulates the growth of algae blooms, leading to what is commonly, if not entirely accurately, called “red tide.” Those algae blooms block out sunlight to underwater plants — often referred to as submerged aquatic vegetation, or SAV — and provide a source of fuel for bacteria that suffocate nearby organisms by consuming the dissolved oxygen from the surrounding water. Dead zones occur in estuaries, where fresh, warm surface water mixes with salty, cool bottom water; as a result, the transfer of oxygen to the bottom is choked off (known as stratification: see chart below).
What happens to living creatures in a dead zone? Imagine you’re launched out of the International Space Station without a space suit. With no surrounding oxygen to breathe, you will die within moments. Marine life also requires oxygen to survive. Whether it’s the sea grass beds that produce additional oxygen and provide habitats for blue crabs, oysters that filter clean water for the Bay, or rockfish sought by commercial and recreational fishers alike, Bay species are threatened by the dead zone.
There are 530 dead zones worldwide at heightened risk from a warmer planet, and the local lessons of the Chesapeake Bay highlight an urgent need to manage this under-appreciated problem. In addition, there is a dynamic feedback relationship between the dead zones across the planet and the ramifications of current climate change trends. The size of the dead zone fluctuates seasonally, driven largely by climate and weather patterns such as wind, precipitation, temperature, and river flows. Rising temperatures and possible shifts in weather patterns and water flow in turn will likely exacerbate the size and negative impacts of the dead zone, as warmer water has less capacity to retain dissolved oxygen.
Ongoing polluting practices and continued warming will exacerbate the size and effects of the dead zone. Nitrogen and phosphorus are the primary nutrients responsible for eutrophication. Although such nutrients do cycle through ecosystems naturally, the levels in the Bay are extraordinarily high largely as a result of: fertilizers and animal waste from industrial agricultural; residential lawn and garden runoff; air pollution deposits from traffic and power plants; and wastewater sewage from urban development throughout the Chesapeake Bay watershed and airshed. Many of these same processes that contribute to the dead zone contribute also to climate change through carbon dioxide emissions.
In Coastal Dead Zones & Global Climate Change, Donald Boesch, PhD, president of the University of Maryland Center for Environmental Science and a leading expert on hypoxia (dead zones), writes that different climate futures will have varying effects on the Chesapeake Bay:
Climate change is likely to affect hypoxia in myriad ways, sometimes with opposing results …. increased streamflow, warmer temperatures, calmer summer winds, and increased depth due to sea level rise … would move the ecosystem in the direction of worsening hypoxia.
Wetter, Warmer = More Nutrients
In short, in a wetter and warmer climate, rivers would run harder and higher in winter and spring, carrying more oxygen-depleting nutrients into the Bay. Conversely, in a more stable climate future, a drier climate would result in lower levels of nutrient input and smaller algae blooms. As a 2010 journal article in Estuarine, Coastal, and Shelf Science notes: “The magnitude of these changes is sensitive to the carbon dioxide emission trajectory, so that actions taken now to reduce carbon dioxide emissions will reduce climate impacts on the Bay.”
Studies put the overall economic value of the Bay, the primary economic engine of the region, at more than $1 trillion. Fisheries, jobs, and livelihoods are at stake, not “only” animals and ecosystems.
Increasing Public Health Concerns
The algal blooms themselves pose threats to human health.
The former director of the National Science Foundation, Rita Colwell, Ph.D, states that nutrient pollution, in combination with warmer water and other factors not present in the Bay’s natural condition, is contributing to the growth rate of a bacterium called Vibrio, which can cause intestinal sickness and life-threatening skin and blood infections (and which also decimates oyster populations). Colwell notes that the growing rate of illnesses is acting as “an early warning system” that nutrient pollution and changing climate are disrupting the natural balance of the Bay ecosystem. In addition, many rural drinking supplies throughout the watershed are being contaminated by nutrient run-off. The link between the quality of watershed drinking water and the health of the Bay and its tributaries is clear, and inaction to solve this problem poses increased health risks.
The connection between dead zones and climate change has gotten scant attention in the mainstream media however, but rather has been limited primarily to academia and advocacy organizations. Many members of the current Congress, supporting industrial interests linked to the discharges, are working hard against court-mandated efforts by EPA to implement its Total Maximum Daily Load (TMDL) plan under the Clean Water Act. Scientists, environmental advocates, and policy managers working on this problem are struggling to ensure that the perilous risks of inaction are communicated effectively to the public.
Mainstream Media Coverage … Generally Lacking
Engaging affected citizens through public dialogue about the dead zone appears critical, and academic articles likely are not enough. If the public is going to understand the dangers facing the Bay and impacts on jobs and the economy of the mid-Atlantic, it is essential that mainstream media coverage expand.
National media coverage of the issue, however, is at best mixed. Although The Washington Post has occasionally covered the dead zone and NPR has discussed efforts to curb agricultural nutrient pollution, discussion of the dead zone is mainly limited to local and niche media outlets, Bay restoration advocates, and environmentally-conscious publications.
Organizations like the Chesapeake Bay Journal and the Chesapeake Bay Action Plan help provide the public with easy-to-understand information about dead zone threats, and the Chesapeake Bay Foundation engages in one of the largest public environmental education campaigns in the country. This past summer, Grist magazine reported on the dead zone, and online sites such as Think Progress and DeSmogBlog are trying to raise public awareness on dead zones around the world. This at minimum is a start.
Evidence indicates in a number of cases that adverse impacts are exceeding what had been projected by many climate change models just a few years ago. Should these impacts continue to prove true and the mid-Atlantic climate becomes wetter and warmer, the dead zone will worsen.
Both “red-blooded” and “tree-hugging” Americans have a shared interest in preventing this outcome. Local support for clean-up efforts is high, as nearly 75 percent of both Marylanders and Virginians favor a pollution diet. And a recently released report by the Chesapeake Bay Foundation found that pollution limits to restore the Bay actually encourage significant job growth (upwards of up to 35 times more jobs than the controversial Keystone XL Pipeline).
Clean-up efforts have an economic, public health, and risk imperative. As Boesch recently said in a telephone interview, “The main ways climate change will affect the Bay will occur in the timeframe of the 2025 TMDL attainment goals. We must act now to ensure that the Bay has the best chance of becoming healthy before it is too late.”
Sam Teicher is a senior at Yale College studying political science with an interdisciplinary concentration in environmental sustainability. On Twitter: S_Teicher12.