Southeast Impacts & Adaptation

Over 70 million people live in the Southeast. ^[1] The region includes many cities with populations over 250,000, including Houston, Jacksonville, Charlotte, Atlanta, Miami, and New Orleans. ^[1] The region's economy includes forestry, tourism, oil and gas production, and agriculture. The Southeast also includes 29,000 miles of coastline. ^[2]

The region's climate is generally warm and wet, with mild and humid winters. Since 1970, average annual temperatures in the region have increased by about 2°F. ^[3] Winters, in particular, are getting warmer. The average number of freezing days has declined by four to seven days per year since the mid-1970s. ^[3] Most areas, with the exception of southern Florida, are getting wetter. Autumn precipitation has increased by 30% since 1901. The number of heavy downpours has increased in many parts of the region. ^[3] Despite increases in fall precipitation, the area affected by moderate and severe drought, especially in the spring and summer, has increased since the mid-1970s. ^[3]

Average annual temperatures in the region are projected to increase by 4 to 9°F by 2080. ^[3] Hurricane-related rainfall is projected to continue to increase. Precipitation in southern Florida will likely decrease. It is unclear how precipitation will change in the rest of the region. Climate models are currently inconclusive as to whether the net change will be an increase or decrease. Models do suggest that rainfall will arrive in heavier downpours with increased dry periods between storms. These changes would increase the risk of both flooding and drought. ^[3] The coasts will likely experience stronger hurricanes and sea level rise. Storm surge could present problems for coastal communities and ecosystems. ^[3]

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Impacts on Coastal Resources

Densely populated coastal areas and coastal ecosystems in the Southeast are already experiencing relative sea level rise, hurricanes, and storm surge. Climate change is projected to exacerbate these existing threats.

Many coastal areas in the Texas and Louisiana are subsiding--local land elevation is sinking relative to sea level. Combined with global sea level rise, local subsidence will lead to a higher "relative" change in sea level at the local scale. Observed subsidence rates in the southeast are significant. For example, in Grand Isle, Louisiana and the plain of the Mississippi River delta, sea level is already rising at rates as high as 0.32 inches per year. ^[4]

Additionally, the southeastern region experiences hurricanes. During some years, hurricanes and the associated storm surges have caused extreme damage. For example, Hurricanes Katrina and Rita caused a loss of over 200 square miles of coastal land in Louisiana. ^[3] The 2005 hurricane season caused over 1,800 deaths and catastrophic damage to personal property and public infrastructure. ^[3]

Projected sea level rise, increased hurricane intensity, and associated storm surge may lead to further erosion, flooding, and property damage in the Southeast.

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Chandeleur Islands, east of New Orleans, before and after 2005 hurricanes; 85% of the islands' above-water land mass was eliminated.
Source: USGCRP (2009)

• Low-lying coastal communities that sit on subsiding land are especially sensitive to sea level rise. For example, a two foot increase in the average global sea level by 2100 would result in a 3.5 foot increase in sea level at Galveston, Texas. The land is sinking in Galveston and in many other areas along the central Gulf Coast. ^[3] For example, New Orleans, Louisiana faces a similar risk.
• Sea level rise along the Southeast coast will likely erode wetlands and coastal shorelines. Low-lying areas would be flooded more frequently. Some ecosystems and communities could be permanently lost. ^[3]
• Hurricanes gain strength over warm ocean waters. The destructive energy of Atlantic hurricanes has increased in recent decades. As the ocean surface continues to warm, hurricane intensity will likely continue to increase. ^{[3] [5]}
• More frequent storm surge flooding of low-lying areas would cause more frequent flooding of transportation infrastructure. This can disrupt travel and damage roads, highways, bridges, oil and gas operations, and other structures in coastal areas. The transportation network is particularly vulnerable since many roads in the Gulf Coast region of the Southeast are at an elevation of four feet or less. ^[3]

For more information on climate change impacts on coasts, please visit the Coastal Impacts page.

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Subsidence in the Southeast

New Orleans, Louisiana, following Hurricane Katrina, showing Interstate 10, looking toward Lake Pontchartrain. This photo is from the U.S. Coast Guard's initial Hurricane Katrina damage assessment of New Orleans. Source: NRC (2010)

Many hydrologic alterations have been made to the Mississippi River to control flooding and improve access for shipping. Alterations include creating channels, dredging waterways, and erecting levees. However, these alterations have drastically decreased sediment flows to areas in the lower Mississippi Delta. These areas rely on sediment for land-building and replacing sediment lost to erosion. These factors, among others have contributed to subsidence — or sinking — of the land in areas like New Orleans.

Coastal areas in the Southeast are already sensitive to sea level rise and tropical storms. The added factor of subsidence will likely increase flooding risk due to storm surges.

During Hurricane Katrina, New Orleans suffered major flooding and loss of human life, property, and land. Changes in the area's hydrology, vegetation, and land, along with inadequate protective structures, contributed to these extensive impacts. Climate change may or may not have contributed to Hurricane Katrina, but this disaster is an example of how human-induced changes can exacerbate the vulnerability of coastal areas to the impacts of storm events.

Impacts on Water Resources

Water resource scarcity can affect many sectors of the Southeast's economy as well as the region's natural ecosystems. Periodic droughts, overconsumption of water resources, and other factors can create water shortages. Managing water resources will likely become more challenging with projected climate changes and anticipated population and economic growth.

• Higher temperatures increase evaporation and water loss from plants. Projected increases in temperature will likely increase the frequency, duration, and intensity of droughts in the area. ^[3]
• Projected changes in surface water runoff to the coast and groundwater recharge will likely allow saltwater to intrude and mix with shallow aquifers in some coastal areas of the Southeast, particularly in Florida and Louisiana. ^[3]
• If the region increases groundwater pumping to offset water shortfalls, then aquifers will be further depleted. In the long term, the depletion of ground water supplies would place additional strain on surface water resources. ^[3]
• Growth in demand will also likely strain water resources. The Southeast region is attracting a great deal of people, investment, and industry. The population of Florida has more than doubled during the past 30 years. Growth rates in most other southeastern states were 45% to 75% over the same period. Decreased water availability will challenge future growth and the quality of life of residents in the region. ^[3]

For more information on climate change impacts on water, please visit the Water Resources Impacts page.

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Impacts on Human Health

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The maps show the number of days per year with peak temperatures above 90°F from 1961 to 1979 and projected for 2080 to 2099. By 2100, north Florida is projected to experience more than 165 days per year (over six months) over 90°F.
Source: USGCRP (2009)

Projected climate changes will stress human health.

• Higher temperatures and more frequent heat waves will likely increase heat stress, respiratory illnesses, and heat-related deaths in the Southeast. High temperatures also correlate with poor air quality and pose a risk to people with respiratory problems. While the number of cold-related deaths is projected to decrease, net climate-related mortality will likely increase. ^[3]
• Increased flooding and hurricanes could present extreme public health and emergency management challenges.
• The spread of some types of bacteria has been linked to warmer temperatures. For example, food poisoning from eating shellfish infected with Vibrio parahaemolyticus bacteria has increased by 41% from 1996 to 2006 in the United States. As temperatures increase, the frequency of these types of shellfish-borne disease outbreaks in coastal waters is likely to increase. ^[3]

For more information on climate change impacts on human health, please visit the Human Health Impacts page.

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Impacts on Ecosystems

Warmer air and water temperatures, hurricanes, increased storm surges, and sea level rise will likely alter the Southeast's local ecosystems and agricultural productivity.

• Warmer temperatures could increase the number of wildfires and pest outbreaks, such as the southern pine beetle. ^[3]
• Declining soil moisture, water scarcity, and increasing temperatures will likely stress agricultural crops. ^[3]
• Sustained temperatures between 90 and 100°F can significantly affect cattle. ^[3] Severe droughts, such as the water shortage that affected Texas in 2011, may lead to the premature slaughtering of cattle.
• Sea level rise and increased storms will likely increase the salinity of estuaries, coastal wetlands, and tidal rivers. Rapid sea level rise could even eliminate some barrier islands that currently protect inland habitats. ^[3]

To learn more about climate change impacts on ecosystems, visit the Ecosystems Impacts page.

To learn more about what the Southeast is doing to adapt to climate change impacts, please visit the adaptation section of the Southeast Impacts and Adaptation page.

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References

[1] U.S. Census Bureau (2011). 2010 Census. Accessed 6/15/2011.

[2] NOAA (2011). Ocean and Coastal Resource Management in Your State: States and Territories Working With NOAA on Ocean and Coastal Management . National Oceanic and Atmospheric Administration. Accessed 6/15/2011.

[3] USGCRP (2009). Global Climate Change Impacts in the United States . Karl, T.R., J. M. Melillo, and T. C. Peterson (eds.). United States Global Change Research Program. Cambridge University Press, New York, NY, USA.

[4] CCSP (2008). Impacts of Climate Change and Variability on Transportation Systems and Infrastructure: Gulf Coast Study, Phase I. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research Savonis, M. J., V.R. Burkett, and J.R. Potter (eds.). Department of Transportation, Washington, DC, USA, 445 pp.

[5] NRC (2010). Advancing the Science of Climate Change . National Research Council. The National Academies Press, Washington, DC, USA.

Adaptation Examples in the Southeast

The Southeastern states are home to approximately 70 million residents. Bordered by the Atlantic Ocean to the east and the Gulf of Mexico to the South, the Southeast is home to a diverse range of land- and seascapes ranging from the coral reefs of the Florida Keys to the mountains of southern Appalachia. The states are already familiar with climate-related and coastal hazards, including hot and humid summers, tornados, and hurricanes. As the climate changes, the Southeastern states will likely have to deal with sea level rise, increased Atlantic hurricane intensity, higher storm surges, more intense precipitation events, habitat changes, more severe droughts, increasing temperatures and heat waves, and salt water intrusion. ^[1]

To learn more about the climate change impacts in the Southeast, visit the Southeast Impacts section. For more information about climate change impacts on coastal areas, visit the Coastal Impacts & Adaptation page.

What follows are examples of ongoing efforts to adapt to climate change impacts in the Southeast at the local, state, and federal level. Given its long, low lying, and storm-prone coastline, many of these examples are focused on coastal issues; however, additional areas for adaptation (e.g., preparing for heat waves) are increasingly being addressed. In the Related Links box on the side of this page, there is a list of links to a number of adaptation plans, reports, and studies specific to the region. Both the examples and links are intended to be illustrative — they are not intended to be comprehensive.

A collaborative effort in Florida protects against sea level rise

The Southeast Florida Region's low land elevations and location along the Atlantic Ocean make it particularly vulnerable to sea level rise, flooding, and tropical storms. In 2009, during the Local Climate Leadership Summit, officials from the region realized that they were presenting slightly different projections about similar potential risks. ^[2] The four Southeast Florida counties (Broward, Miami-Dade, Palm Beach, and Monroe) created the Southeast Florida Regional Climate Change Compact to unify efforts. The Compact counties established a unified sea level rise projection (PDF) for the region, identified consistent methods for mapping inundation and assessing the vulnerability of resources to sea level rise, and successfully advocated for the Florida Legislature to recognize the term "Adaptation Action Areas" where flooding from sea level rise or storm surges will place public and private infrastructure at risk. ^[3] The Compact also published a Regional Climate Action Plan.

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The Biscayne Aquifer, in yellow, is a shared resource between the four counties in the Southeast Florida Region, outlined in black. Saltwater intrusion from sea level rise may threaten drinking water supply quality for the four counties. Source: USGS (2010) (PDF)

Southeastern states address sea level rise

With the assistance of the National Oceanic and Atmospheric Administration Office of Ocean and Coastal Resource Management (NOAA/OCRM), many Southeastern states are addressing sea level rise through research, modeling, mapping, and developing planning documents, including the following examples.

• The Georgia Sea Grant Program funded a study to assess shoreline change rates and coastal hazards on Georgia's barrier islands. ^[4]
• To monitor sea level rise, wetland loss, and erosion, the North Carolina Division of Coastal Management is working on a project to map the estuaries, shoreline types, and coastal structures in North Carolina. ^[5]
• To address coastal erosion, the South Carolina Office of Ocean and Coastal Resource Management regularly updates the "40-year setback line" that establishes boundaries for development and established a Shoreline Change Initiative to bring together researchers, agencies, and stakeholders to prepare for and adapt to shoreline changes. ^[4]
• In Louisiana, after Hurricane Katrina, the Army Corps of Engineers redesigned some levees and other flood protection structures to withstand higher storm surge and wave action. ^[1]

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Recent upgrades that raised the height of this earthen levee increased protection against storm surge in the New Orleans area. Source: USGCRP (2009) (PDF)

North Carolina prepares for climate change

North Carolina is preparing for several climate change threats, including sea level rise, severe storms, flooding, heat waves, and droughts. ^[6] In 2010, the North Carolina Department of Environment and Natural Resources (NCDENR) published the Climate Change Initiative Strategy Framework to identify feasible mitigation and adaptation strategies addressing sea level rise, climate-sensitive ecosystems, water management, public health impacts, emergency preparedness, and land use planning and development. The North Carolina Interagency Leadership Team organized a statewide climate change adaptation workshop in 2010 — "Planning for North Carolina's Future: Ask the Climate Question."

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Climate Ready Estuaries program addresses climate change in coastal areas

Source: EPA

Several National Estuary Programs (NEPs) in the Southeast are working with EPA's Climate Ready Estuaries Program to address climate change in coastal areas. For example:

• The Charlotte Harbor NEP conducted a vulnerability assessment, identified climate change indicators, and worked with the City of Punta Gorda, Florida to develop adaptation options.
• The Indian River Lagoon NEP assisted the City of Satellite Beach, Florida to assess sensitivity to sea level rise and is investigating changes in wetland habitat to inform future land-use and conservation plans.
• The Sarasota Bay Estuary Program is developing an adaptation plan that includes public outreach and supports updating local comprehensive plans with adaptation measures.
• The Tampa Bay Estuary Program is working to identify actions for improving resiliency in estuarine restoration and protection plans in all coastal communities along the Gulf Coast.
• The Albemarle-Pamlico NEP held public listening sessions to discuss the combined impacts of sea level rise and population growth and is developing an adaptation communication strategy for policy makers.

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References

[1] USGCRP (2009). Global Climate Change Impacts in the United States. Karl, T.R., J. M. Melillo, and T. C. Peterson (eds.). United States Global Change Research Program. Cambridge University Press, New York, NY, USA.

[2] Institute for Sustainable Communities (2010). Promising Practices in Adaptation & Resilience. Version 1.0. (PDF) Produced in partnership with Center for Clean Air Policy.

[3] Broward County. Southeast Florida Regional Climate Compact . Accessed 03/16/2012

[4] Rubinoff, P. N.D. Vinhateiro, C. Piecuch. (2008). Summary of Coastal Program Initiatives that address Sea Level Rise as a result of Global Climate Change. (PDF) Rhode Island Sea Grant/Coastal Resources Center, University of Rhode Island.

[5] North Carolina Department of Environment and Natural Resources. Estuarine Shoreline Mapping Project .

[6] North Carolina Department of Environment and Natural Resources. One North Carolina Naturally. Projected Climate Threats to North Carolina .