Climate changes and the local environment:
Within the past century, the levels of potent greenhouse gases, such as carbon dioxide, in the atmosphere have greatly increased. This has led to an increase in global average temperatures and has already had profound consequences worldwide. The upward trend in temperature has altered sea levels, as warmer surface temperatures lead to a rise in global sea levels.
Higher temperatures contribute to sea level rise in two ways, from the melting of the ice caps and thermal expansion. Warming oceans have significantly accelerated the melting of arctic ice caps, which release freshwater into the ocean. Because freshwater is less dense than salt water, when it melts into the ocean it contributes a greater volume than the original glacier did. Additionally, warmer oceans experience greater levels of kinetic energy. This increase in molecular movement causes an expansion of the oceans’ volume, only furthering the impacts of warming temperatures on sea level rise.
Fairfield County has already seen the impacts of global sea level rise, given its location on the coast of Connecticut. Bridgeport, one of largest cities in the County, reported 5 inches of sea level rise since 1964. In addition to rising tides, the County has faced an increase in annual levels of precipitation. As global temperatures rise, the atmosphere is capable of holding more moisture, allowing for this gradual increase in rainfall. Within the past century, Fairfield County has seen a steady increase in overall precipitation levels. It is important to note not just this overall increase, but also the increase in the number of severe storms in Fairfield County.
Data for the number of heavy downpours in Connecticut shows variation from year to year, but a clear upward trend since the 1950’s. Warmer temperatures increase the amount of water that evaporates off the ocean, leading to a greater amount of water vapor in the atmosphere. Thus, there is more water available when it does rain, causing these overall heavier downpours. These severe storms, in addition to rising sea levels, have increased the risk of coastal flooding for Fairfield County. With heavy rainfall and already higher sea levels, the damages the County faces from storms has been severe and will likely worsen in the coming years as well.
How we know:
These reconstructions are based on easily-accessible online tools, including the National Oceanic and Atmospheric Administration’s (NOAA) Tides & Currents tool, the NOAA Climate at a Glance app, as well as Climate Central’s research report.
NOAA’s Tides & Currents tool generates graphs of monthly mean sea levels for individual cities and counties. These graphs use sea level data collected from one of hundreds of sea level stations across the country, and include a long-term linear trend line.
NOAA’s Climate at a Glance app uses data collected at weather stations and stored in NOAA's U.S. Climate Divisions database to create graphs about temperature, precipitation, and drought. This app can generate graphs that present global, regional, and local trends.
Climate Central’s Heaviest Downpours research report displays the increase in heavy downpours in the United States. At each station, a heavy downpour was defined as the top 1 percent daily precipitation amounts over the period from 1950 to 2014. The analysis is based on precipitation observations from 2,962 climate stations across the US.
Rising sea levels, an increase in overall precipitation, and more severe storms have greatly increased Fairfield County’s risk for floods. Over 130,000 people in the state are currently at risk of inland flooding, and this new surgance in downpour storms and rising sea levels have strained the County’s sewer system. This stress on the County’s unprepared infrastructure has severely impacted both human and aquatic health.
In particular, the rise in precipitation and increasing number of heavy downpours have increased levels of runoff. Within Fairfield County, the city of Bridgeport operates under a combined sewer system, meaning that rainwater runoff, domestic sewage, and industrial wastewater are all transported within the same pipe. During heavy storms where the rainfall exceeds the system’s capacity, the system is designed to overflow and release excess water into nearby bodies of water.
These overflows, called combined sewer overflows (CSOs), produce considerable impacts on the local environment of Fairfield County. CSOs present an environmental and public health risk for the County, as the untreated wastewater that is discharged can contain bacteria, raw sewage, excess nutrients from fertilizers, and chemicals. This particularly impacted Bridgeport, as portions of the city’s sewer system were built over 100 years ago.
The Connecticut Department of Energy and Environmental Protection found that a CSO occurs whenever there is 0.4 inches of precipitation or more. Overflows from the system occur on average every 10 days, releasing between 100,000 and 500,000 gallons of contaminated water into local rivers, streams, and harbors. With the increasing rate at which heavy downpours are taking place in Bridgeport, this leaves the public exposed to bacteria and raw sewage, creating a considerable health risk.
The increasingly high levels of contamination also negatively affect recreational activity, often leading to the closure of multiple beaches and parks. In Bridgeport the following parks, beaches, and harbors are constantly affected: Ash Creek, Bridgeport Harbor, Black Rock Harbor, Pequonnock Harbor, Johnson’s Creek, Yellow Mill Pond, Cedar Creek, Burr Creek and Island Brook.
Further, the loss of fishing grounds in Bridgeport have greatly disturbed the fishing industry. Leaked sewage has and will continue to kill tens of thousands of acres of shellfish beds. Additionally, hypoxia, or the overgrowth of algae that leads to dangerously low levels of oxygen for aquatic life, will continue to appear throughout the County as excess fertilizers enter these ecosystems. These “dead zones” are detrimental for aquatic species and will only further degrade the County’s water quality.
Fairfield County, and specifically the Bridgeport Water Pollution Control Authority (WPCA), have already taken measures to combat the damages from CSOs. The WPCA has developed a plan to minimize the number of CSOs, and has implemented green infrastructure to prevent or delay stormwater from entering the sewer system. Although these efforts have helped reduce the number of overflows, Fairfield County nevertheless must invest in more infrastructure and a new system in order to mitigate the damages caused by stormwater runoff and severe floods.
Some CT beaches considered among the dirtiest. EyeWitness News
Water quality at Bridgeport, Fairfield beaches dropped in 2016. CT Post
Bridgeport plans massive sewer upgrades. CT Post
Combined Sewer Overflow Guide for City Employees. Bridgeport WPCA
Article author: James Loughran, Georgetown University
Article editor: Maddie Bowen, Georgetown University