Patterns of climate risk, social vulnerability, and climate adaptation in the Southeast echo centuries of human history. The region consists of highly diverse communities and landscapes, including one of the most biodiverse areas in the continental United States. The Southeast’s ecosystems, stewarded for generations by Indigenous Peoples, are now in a precarious state. Centuries of political and land-use decisions have threatened the landscape and the people, with a few prospering at the expense of many. These decisions, shaped by a long history of systemic and structural racial discrimination and aggression, continue to have lasting harmful effects on the preparedness of Southeast communities for mounting climate change threats. The institutions of slavery and intergenerational ownership of individuals as property, Jim Crow segregation, and housing discrimination have resulted in many BIPOC (Black, Indigenous, and People of Color) communities living in neighborhoods that are disproportionately exposed to environmental risks and with fewer resources to address them when compared to majority White communities (Figure 32.18).1,2,3,4,5,6,7,8,9,10,11,12,13 Furthermore, these frontline communities—those with higher exposures, greater vulnerability, and less adaptive capacity to climate change impacts—continue to face forms of discrimination that increase their vulnerability to climate risks and reduce their options for resilience (Figure 20.1).1,14,15 These inequities are further complicated by the Southeast’s population changes, economic investments, and rising tax revenues in urban and suburban areas. Wealthier communities are able to seek out external resources needed to implement innovative climate resilience and adaptation projects.16,17 Meanwhile, smaller and more rural communities often lack the capacity to receive and spend funding, train leadership, and advocate for climate adaptation planning.18
Hoffman, J.S., S.G. McNulty, C. Brown, K.D. Dello, P.N. Knox, A. Lascurain, C. Mickalonis, G.T. Mitchum, L. Rivers III, M. Schaefer, G.P. Smith, J.S. Camp, and K.M. Wood, 2023: Ch. 22. Southeast. In: Fifth National Climate Assessment. Crimmins, A.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, B.C. Stewart, and T.K. Maycock, Eds. U.S. Global Change Research Program, Washington, DC, USA. https://doi.org/10.7930/NCA5.2023.CH22
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With virtually no exceptions, climate change in the Southeast continues to exhibit the trends that were reported in the last National Climate Assessment (NCA).19 We now better understand the increasing intensity of climate stressors in the Southeast, including extreme heat, extreme precipitation events, drought persistence and strength, sea level change, and tropical cyclones (Table A4.1), as well as decreases in the intensity and frequency of disruptive cold-season events like snowfall and frost days (Ch. 2).20
There have been notable advancements in Southeast climate change adaptation in recent years.19 For example, adaptation plans created by Tribal Nations have contributed to those Nations’ cultural continuance in a changing climate—that is, their “capacity to maintain members’ cultural integrity, health, economic vitality, and political order into the future and avoid having members experience preventable harms” (KM 16.3).21,22 Indigenous stewardship continues in the Southeast in many contemporary Indigenous “cultural landscapes,” or places where Tribal members have centuries-old connections (Box 22.3). In these places, members continue cultivating cultural practices including hunting, fishing, foraging, and ceremony.23 The increasing hazards of climate change, pollution, and threats to land and water rights–which may be underestimated by existing environmental justice analyses24,25–put a strain on Indigenous Peoples’ sovereignty and their ability to have high levels of cultural continuance.21,22,26
Moreover, communities throughout the Southeast are exploring how to spur action through communicating about climate change science across both formal (classroom) and informal (outside of classrooms) learning,27,28,29,30,31,32,33 setting clear climate goals,34 and responding to the mounting threats and stressors that climate change presents (Figure 31.1).35 However, there has been an equal, if not a greater, number of failures to adequately prepare the region’s homeplaces, infrastructure, economy, and livelihoods for the threats of a warming climate, seen in the poorly coordinated responses to hurricanes over many years, from Hurricanes Katrina36 to Florence37 and Ida,38 especially for frontline communities.39 Moreover, uncoordinated adaptation efforts across municipal and state boundaries to address climate change may hinder the long-term efficacy of any individual project while delaying the shared goal of securing the vitality of the Southeast.
Joan HartAfter Irma(2022, acrylic on canvas)Artist’s statement: This painting was inspired by aerial photos of damage in the Florida Keys following Hurricane Irma. As hurricanes become more powerful due to climate change, and as people continue to build along the coast in vulnerable areas, these scenes will repeat. My intention with this painting was to draw people in with strong colors and what seem, at a distance, to be abstract shapes. Upon closer look, the damaged houses, boats, and debris left in the wake of this horrendous storm become apparent. Can hope be found amidst disaster?View the full Art × Climate gallery.Artworks and artists’ statements are not official Assessment products.
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The Southeast’s population has grown and is expected to continue growing, mostly in metropolitan areas and along its coastline (very likely, very high confidence), putting more communities and their assets into harm’s way from increasing risks related to climate and land-use changes (very likely, very high confidence). Conversely, many rural places are facing declining populations with a growing percentage of older residents (very high confidence), making these areas particularly vulnerable to the impacts of a changing climate (likely, high confidence). At the same time, decision-makers frequently use outdated and/or limited information on climate-related risks to inform adaptation plans, which as a result fail to account for worsening future conditions (likely, high confidence). These climate adaptation efforts also tend to be concentrated in wealthier communities, leaving under-resourced and more rural populations, communities of color, and Tribal Nations at growing and disproportionate risk (likely, high confidence).
All but one of the Southeast’s states—Mississippi—experienced population growth over the last decade, and most of the fastest-growing large US cities are located in the region.40 Even under scenarios with moderate population growth (e.g., Shared Socioeconomic Pathway [SSP] 2), the region’s population is expected to increase (Figure 22.1).41
Southeast land cover equal to about 1.7 million football fields changed from forested to developed between 1985 and 2019, more than in any other NCA region (Figure 22.2a; Ch. 6). Urbanized land cover is estimated to increase by more than 9% throughout the region by 2060, based on urban area growth trends during 1990–2010,42 further threatening the region’s unique terrestrial and aquatic biodiversity (Figure 22.2b; KM KM 8.1).
Unconstrained exurban and suburban sprawl will further expose human development to weather- and climate-related risks such as wildfire,44 hurricanes,45 floods,13,46 intensifying thunderstorms,47 and tornadoes.48 Growth along the region’s coastlines49 has increased the population exposed to coastal-specific climate threats.13,50,51,52,53 Although the Southeast has historically experienced more billion-dollar disaster events than the rest of the country54 and has weathered multiple hurricanes since 2018 (Figure 22.3), there is considerable regional variation among residents’ perceptions of whether climate change will personally harm them.55,56
Some of the Southeast’s growth follows patterns of urban renewal, with affluent and young people returning to urban areas and displacing under-resourced communities to suburban and rural areas.57 As a result of this displacement and long-standing underinvestment, under-resourced communities face more environmental hazards and increasing risks (Figure 22.4b)3,13 but have less access to climate-ready infrastructure such as housing (Figure 22.4a), dwellings with strong building codes58 that minimize disruption during storms,59,60 public transit,61 community resource centers for heat and cold relief,62 and up-to-date stormwater management systems.63 These communities often also lack a well-resourced local and/or state governmental workforce64 to analyze, plan for, and mitigate risks (KM 20.1).16,17,18,65,66
Southeast flood risk is inequitably distributed due to both climate and non-climate stressors. Physical stressors such as increases in rainfall, temperatures, and sea level, in addition to land cover change, exacerbate flood risks (KM 4.2),13,50,67,68 while social and economic policies, including institutional investments and disinvestments, differentially shape risk, vulnerability, and exposure to flooding.69,70,71 Compounding preexisting social and economic disparities are changes in precipitation patterns. For instance, shifting autumn precipitation patterns have been attributed to human-caused climate change,72 and some Southeast counties with higher social vulnerability are experiencing more frequent flooding.73
Mandatory flood risk disclosure requirements largely depend on state-by-state policies,74 and virtually all requirements apply only to home sales. Millions of rental housing units in the region are within counties that have high Expected Annual Loss ratings from FEMA,75 and confidence is growing that areas currently populated by communities of color, who also are more often renters, will face disproportionately high future flood risks (Figure 22.4).3,13 Furthermore, other forms of housing that are vulnerable to climate risks include mobile homes and manufactured housing, which are concentrated in the Southeast.40,76,77 These populations tend to face more barriers to accessing flood insurance and federal flood disaster assistance and more often experience adverse outcomes during disaster recovery, due in part to the lack of disaster relief programs for renters and the rising cost of flood insurance.78,79,80 Additionally, the potential overvaluation of coastal residential housing stock makes it even more challenging to move people out of harm’s way due to the upper limits placed on the amount of compensation these programs can offer and peoples’ reluctance to sell these properties and lose rental revenue. For example, in Miami-Dade County, Florida, the total overvaluation of properties is $3.9 billion, and in nearby Duval County, where Jacksonville is the county seat (Figure 22.5), overvaluation exceeds $420 million.81 Across the Southeast, the average total overvaluation of properties is estimated to be around $110 million per county. Florida has the highest statewide total average overvaluation at $749 million, while Mississippi has an undervaluation of $20 million.81
Flooding impacts infrastructure and, in turn, public health. Injury, illness, and death can result from exposure to mold from floodwater damage,82,83 onsite wastewater treatment system failures,84 and carbon monoxide poisoning from misuse of generators for emergency power.85,86,87 In addition, healthcare facilities may be damaged by flooding or unable to handle an influx of demand.88,89 Damage to roads and bridges might prevent access to these facilities, disrupt the supply of medications and equipment,90 and hinder a community’s lifeline to emergency services and evacuation routes.91
Tropical storms and hurricanes have been responsible for some of the Southeast’s biggest and most damaging flooding events since 2018 (Figure 22.3). The likelihood of hurricanes slowing down or stalling near the coast has increased, exacerbating the rainfall-related flooding threat from these systems.92 However, the impact of climate change on slowing down or stalling tropical storms remains uncertain,92 although some simulations indicate a potential slowdown of Atlantic storms due to climate change,93,94 including near the Southeast US coast.95,96 In addition, rapidly intensifying hurricanes have presented challenges for implementing evacuations,97 and the frequency with which Atlantic hurricanes rapidly intensify may be increasing in response to long-term human-caused climate change.98 Also, there is evidence of increased intensification rates near the US Atlantic coast, which may continue into the future.99 There have been significant improvements in understanding how nontropical systems,100 atmospheric rivers,101,102,103,104,105 past and future El Niño–Southern Oscillation patterns,106,107 flash flooding,73,108 and urban environments109,110,111,112,113 add to the Southeast’s risk of extreme precipitation and flooding.
With additional global warming, more North Atlantic hurricanes are expected to strengthen to at least Category 4 intensity and to undergo rapid intensification, sea level rise is expected to worsen storm surge inundation, and tropical cyclone–related rainfall is expected to increase.93,114,115,116,117 The likelihood of storms making landfall could increase, which may offset the potential decrease in the total number of storms and overall exacerbate impacts.118 However, some uncertainty remains regarding the expected degree of change in hurricane activity impacting the Southeast. Additionally, estimates suggest that some seasonal, annual average, and extreme precipitation amounts across the Southeast will increase, driven mainly by more extreme events (e.g., precipitation of 3 inches or more in 24 hours) at higher levels of warming.20,67,119
Some Southeast communities plan for these extreme events with an outdated understanding of climate-related risks.68,120,121 Sewer infrastructure is built to accommodate a particular amount of rainfall over a specified time, and current estimates of precipitation intensity, frequency, and duration generally do not consider future projections of these metrics, posing a significant challenge to civil engineers.122,123 Estimating future precipitation characteristics and their impact on sewer infrastructure in the Southeast is primarily conducted on a state-by-state basis and relies on different scientific approaches,121,124 further complicating the development of design standards for climate-ready infrastructure (Figure 22.5; KM 12.2).120
Extreme rainfall that occurs at the same time that ocean water inundates populated areas (e.g., because of high tides or storm surges) creates compound flooding events, which can result in decreased property values125 and roadway obstructions that can hinder first responders (KM 9.2).66,126 Compound flooding events already affect low-lying areas in the coastal plain,93,127 and the Intermediate-Low and Intermediate sea level rise scenarios for the Southeast project a higher frequency of compound flooding by midcentury in regions along the Atlantic coast.128
Tide gauges throughout the Southeast indicate that relative sea level rose by 6 inches during the 1970–2020 time period, with some variation across the region.51 The average range of sea level rise by 2050 relative to 2000 in the Southeast (Low to High scenarios)51 is 16–23 inches (0.40–0.58 m). This increases to a range of 2.2–7.3 feet in 2100 relative to 2000 under the same scenarios.51 These regional estimates are higher than the projected global average rise due to regional variations in land motion, excessive groundwater pumping,129 and the effects of sea level changes caused by changes in ocean currents.51 For example, overall sea level rise projections by 2050 are 22–32 inches for Grand Isle, Louisiana, 10–19 inches for Jacksonville, Florida, and 15–22 inches for Outer Banks, North Carolina. High tide flooding events in the Southeast may increase by a factor of 5–10 by 2050 due to sea level rise (Figure 22.5).51 However, many communities will experience comparable increases in these events before 2050 due to changes in tides that exacerbate sea level rise.52 Saltwater intrusion from rising sea levels has already degraded the health of coastal forests and estuaries while reducing their ability to store carbon,130,131 and increased soil salinity has reduced yields in the remaining range and farmland.132 While there is uncertainty in how global ice sheets will respond to additional global warming and thus ultimately determine longer-term sea level rise, the Southeast could experience 3.1–13.2 feet of sea level rise by 2150.51
Daniel KarikoLast Camp on Isle Derniere, Louisiana(2017, photography)Artist’s statement: Louisiana is experiencing the highest rate of coastal erosion in America. Major storms, including Katrina and Rita in 2005, and Ida in 2021, have drastically changed the geography of Louisiana’s coast. Many of South Louisiana’s communities, including Indigenous Americans, Cajuns, and Asian Americans are affected by loss of natural resources, economic impact, and direct loss of property. People of Louisiana are closely defined by the landscape they inhabit. Yet every year, small local communities gradually sink into the wetlands. This subject is a proverbial “canary in the mine” for issues that affect the entire planet.View the full Art × Climate gallery.Artworks and artists’ statements are not official Assessment products.
Indigenous communities have long faced displacement from and loss of cultural and desirable lands from settlers and government (Figure 16.1). Settler colonialism and climate change are forcing the displacement of Indigenous communities once again, causing stress and grief (KM 16.1). Indigenous communities experience substandard housing and infrastructure, as well as limited insurance coverage, which increases their vulnerability to climate stressors (KM 16.2).134 In addition, land dispossession in the Southeast has impeded Indigenous Peoples from enduring climate hazards and deprived them of the benefits of the natural environments they once stewarded.135,136,137,138
Climate change and a shift from Indigenous-managed cultural landscapes to settler-managed landscapes threaten cultural knowledge and practices.136 This shift can be seen in the loss of plants and animals of cultural significance to Southeast Indigenous communities (Figure 22.2; Box 22.3). This loss has contributed to decreased physical and mental well-being as Tribal citizens have had to shift away from subsistence lifestyles that connect them to their cultural landscapes and contribute to cultural continuance.22,139 Climate change also alters the ranges of native plants while enhancing the growth of invasive species that may out-compete them.140 The loss of native species adversely affects Indigenous populations who rely on these resources for subsistence or cultural value,141 such as coastal communities with economies driven by forests or fisheries.142 However, Tribal Nations are finding ways to lead in responding to climate change (KM 16.3) while exercising their rights to cultural continuance and sovereignty through numerous actions and projects, including revitalizing rivercane ecosystems (Box 22.3).
Southeastern archaeological sites reveal a rich history of how Tribal Nations have met challenges similar to those they are experiencing now by using their Indigenous Knowledges.143 However, many of these sites are exposed to the threat of rising sea level because they are located in coastal lowlands.144 A sea level rise of approximately 3 feet (about 1 m) could result in the loss of more than 13,000 historic and prehistoric archaeological sites (with significantly more lost under more severe scenarios) while directly harming contemporary Indigenous communities across the Southeast.144 Sea level rise also threatens coastal marshes in the Southeast more than anywhere else in the US.145 The potential loss of these marshes, teeming with biodiversity and critical ecosystem services, could adversely affect the communities that depend on them. The ability of marshes to move (or “migrate”) landward in response to sea level rise will depend on the availability of onshore land that in many cases is already developed. Planning for the migration of marshes will require a further understanding of their dynamics, as well as social trade-offs to accommodate their migration into new areas.145
The Southeast is responding to climate threats; however, these actions are spread unevenly across the region (Figure 31.1). Many communities are adopting adaptation plans, including anticipating population growth due to climate-driven relocation.146,147,148 Tribal governments achieve greater success in developing comprehensive climate adaptation plans when joining strong cross-Tribal networks that share knowledge of effective strategies.149 However, Southeastern adaptation plans (especially for drought and heat) are less comprehensive than those in other regions.150,151,152,153
Adaptation actions include avoidance, planned relocation, protection, accommodation, or some combination of these. Avoidance involves limiting development in hazardous areas. Retreat from the coast or riverine floodplains involves removing infrastructure, housing, and public facilities from hazardous areas over time while limiting future development. Protection strategies use physical infrastructure like seawalls, levees, and beach nourishment, although these may not provide long-term protection if designed for past climate conditions.154 Accommodation involves elevating structures or using building materials that can withstand being submerged by floodwaters or are less prone to damage when exposed to fire (Figures 22.6, 22.7).
Funding needed to implement adaptation projects remains elusive for many communities, especially those with limited resources and high levels of preexisting social vulnerability.80,155 One strategy for advancing climate adaptation is applying for FEMA Hazard Mitigation Assistance (HMA) grants.156,157,158 However, state hazard mitigation officers who manage these grant programs have described differing levels of capacity to help local governments develop and implement HMA grants.16 While FEMA updated its hazard mitigation planning guidance in 2022 to require that local governments and states address equity and future conditions as part of their new strategic plans,156 the impacts of these changes have yet to be effectively assessed relative to the quality of the plans. Despite these challenges, a growing number of localities are factoring intensifying climate-related stressors into adaptation plans35,159,160,161 and helping guide new policy (Box 22.2).
There are several types of climate adaptation tools available to communities in the Southeast, including buyouts, information clearinghouses, land use policies, and city design and planning (Figures 22.6, 22.7).
Buyouts—acquiring hazard-prone housing that is demolished and converted to open space—are widely recognized as one of the most cost-effective strategies for reducing future losses,162,163 including those associated with adapting to a changing climate.164 However, while buyouts do require that the land be converted to open space after purchase, applying other proactive land-use planning techniques that guide development to safer locations or limit future growth in hazard-prone areas remains an uncommon practice.165,166 As a result, there remains considerable uncertainty around whether communities are actually reducing risk when accounting for the losses avoided with buyouts relative to increased hazard exposure associated with new development in hazard-prone areas.167,168,169 For example, some buyouts resulted in people relocating to an area of similar risk as their original dwelling,170,171 and relocation in a broader context has meant moving from one risk zone to another.172 Buyouts can also reduce a community’s tax base, which can be particularly devastating in smaller jurisdictions with limited revenue to support governmental services.173 Questions of equity in buyouts include whether buyouts are preferred by residents, whether choosing to participate in buyouts is in their best interest, and whether frontline communities are involved in deciding how and where buyouts occur (KM 20.5; Figure 20.3).174,175,176,177,178,179 Additional buyout challenges include the long-term management of resulting open spaces, tracking buyout land in a given area, and strategies to achieve co-benefits such as creating climate-resilient recreation amenities like parks, greenways, water retention areas, and ballfields.180,181,182 Buyout migration and relocation from one place may also exacerbate local housing pressure in another. For example, in Miami, wealthier individuals are moving from higher-flood-risk coastal areas to safer higher-elevation areas, increasing inland property values and displacing residents,183,184,185 although the exact pressures driving gentrification and displacement within any community are complex.186,187 There is evidence that points to the migration of some Black residents out of floodplains in the Southeast, including the case of Edgecombe County, North Carolina, where the Town of Princeville, discussed in Box 22.1, is located.53
A growing number of climate adaptation resource clearinghouses are available (KM 31.4), and they include Southeast case studies.188,189 In addition, Southeast-focused organizations like the Southeast Climate Adaptation Science Center, USDA Southeast Climate Hub, and the Southeast and Caribbean Disaster Resilience Partnership provide resources needed to advance adaptation strategies, including resources for rural and/or under-resourced communities.18,64 Some climate change planning documents even now center on additional considerations such as equity in their frameworks.190 However, inequitable access to resources and constraints on workforce capacity to effectively use these tools can also lead to unequal progress toward implementing strategies across communities.
Climate-resilient community design principles are being employed by urban planners, landscape architects, and architects, as well as by an increasing number of municipalities (Figures 22.6, 22.7, 12.8).
Human health and climate stressors are intimately linked in the Southeast (very high confidence). Community characteristics such as racial and ethnic population, chronic disease prevalence, age, and socioeconomic status can influence how climate change exacerbates, ameliorates, or introduces new health issues (very high confidence). Climate change is already impacting health in the region (very likely, very high confidence). There are effective strategies to address the health impacts of climate change in the Southeast that have multiple benefits across social and environmental contexts (high confidence).
Public health status is an important indicator of vulnerability to climate stressors,190,195 and Southeasterners are consistently ranked among the unhealthiest in the Nation, with shorter life expectancies than the US average (Figure 22.8).196 Health disparities in the Southeast are related to various social determinants of health, such as lack of access to healthcare, low socioeconomic status, and poor health behaviors (e.g., smoking and drug and alcohol abuse).197 Sedentary lifestyles are reinforced by the quality of the surrounding built environment: the Southeast is home to 8 of the 10 least-walkable cities,198 15 of the 20 most dangerous cities for pedestrians,199 and 4 of the top 10 deadliest states for cyclists in the United States.200
The Southeast has more Black residents than any other NCA region,40 and health-related challenges faced by communities with majority Black populations differ from those with majority White, Hispanic, or Asian populations.201 Communities with majority Black populations tend to have even lower life expectancies and less access to resources that promote health, such as grocery stores, safe places to exercise, and quality healthcare than whiter and wealthier populations.202 These communities also have fewer opportunities for economic prosperity (Figure 22.12), fewer employment opportunities, limited access to quality education, and higher unemployment rates, all of which shape health outcomes.11 Black communities in the Southeast, therefore, shoulder a disproportionate level of health risk associated with climate change.3,12
Extreme heat affects everyone, but particularly at risk are pregnant people;203,204,205 people with heart and lung conditions;206,207 older adults and young children;208,209 people with mental health conditions;210,211 outdoor workers in construction, agriculture, and the service industry;212,213 athletes;214,215,216 and populations who lack adequate shelter or are incarcerated.217,218
Southeasterners rely on air-conditioning to cool living spaces, and air-conditioning demand is expected to grow across the Southeast as the climate warms.219 However, air-conditioning prevalence varies along racial and economic lines.220 Furthermore, the Southeast has high rates of households that experience energy insecurity.221 While the Southeast has the lowest energy rates in the US, households there pay the country’s highest energy bills.222 High energy bills disproportionately impact rural and under-resourced residents, elderly residents on fixed incomes, and communities of color (Figure 22.9).222 Historical de facto as well as de jure segregation policies such as redlining—the New Deal–era practice of classifying communities with significant Black, Asian, and immigrant populations as hazardous for financial investment—neighborhood housing covenants, and urban renewal have had lingering effects on frontline communities in the Southeast, resulting in their low proportion of homes that are energy efficient and affordable.222 There is evidence that the number of blackout events (power outages) affecting more than 1,000 residents for more than one hour due to increasing energy demands and extreme weather events is increasing.223,224,225 The Southeast has experienced many such blackout events annually and during the warm season (May–September) since 2011 (Figure 22.10).226
Public cooling centers are temporary health interventions for those without adequate air-conditioned shelter on exceptionally hot days (KM 15.3). However, in some areas of the Southeast, these centers are not located within walking distance of the populations most in need.228 Furthermore, the Southeast has the lowest public transportation access for households without a private vehicle.229
Heatwaves in the Southeast are happening more frequently and are occurring during a longer heat season, with some cities also showing increasing trends in their duration and intensity (Ch. 2).3,230,231 The number of extreme warm days (above 95°F) is expected to continue increasing with every increment of global warming (Figure 22.9b; Ch. 2). Wet-bulb globe temperature (WBGT)—which measures the combined effects of temperature, humidity, wind, and sunlight on thermal comfort and which may be a better metric for the Southeast than more traditional measures of extreme heat232,233—has already increased due to anthropogenic climate change in parts of the region234,235 and is expected to increase across the region throughout this century.230,235 Additional heat stress within cities can be attributed to the urban heat island effect (Figure A4.4), whereby cities experience warmer temperatures than outlying rural areas and some neighborhoods within a city are hotter than others.236,237 Heat island intensities across the Southeast are systematically higher in formerly redlined communities5 and in counties with higher proportions of Black, Hispanic, and Asian residents, people with education no higher than a high school diploma, people with lower median incomes, and single-parent households.238 However, there is a lack of consistent and appropriate thresholds used to evaluate heat risk. For example, most work-related heat illnesses across five Southeast states occurred below the heat index range designated as dangerous by the National Weather Service.239
Climate change is increasing the risk of multiple dangerous weather events occurring simultaneously or in close proximity, resulting in worsened health effects (Ch. 15). An example of this is when a heatwave occurred after Hurricane Laura devastated the coast of Louisiana in 2020, resulting in at least eight deaths due to heat and an increased risk of heat-related illness, particularly for those who lost electricity and outdoor workers assisting with the recovery.240
In response to heat threats, Miami has institutionalized the first city heat officer to coordinate heat preparedness and response efforts to reduce impacts to the most vulnerable.
In the Southeast, climate change threatens Clean Air Act improvements by creating favorable conditions for increases in smog241,242,243 and wildland fire emissions.244,245,246 The Southeast already has significant amounts of particulate matter (PM2.5; Figure 22.11a) as a result of anthropogenic pollutants247 and extensive vegetation,248 and the associated health effects are experienced disproportionately by communities of color and populations with lower socioeconomic status (Ch. 14).249,250 Future premature deaths due to PM2.5 in the region could be avoided through significant emissions reductions, even when considering future warming (Figure 22.11b; KM 14.3).3,251,252 This is particularly relevant to the Southeast, which is projected to have the highest number of premature deaths due to climate-induced increases in PM2.5 and ozone exposure.3,251,252
In addition, airborne pollen can pose significant health risks to populations living in the southeastern United States.253 Since 1992 in Atlanta, tree pollen concentrations have increased by approximately 4% in the spring and 10% in the fall, and weed pollen has increased by approximately 5% in the spring.254 Some species of trees and weeds are exhibiting an earlier and longer pollen season, correlating with warmer spring temperatures.254 Pollen increases pose significant health risks, including aggravating respiratory conditions such as asthma, which has been linked to a loss of school and work days (KM 14.4). These health risks are expected to worsen as pollen seasons shift earlier and lengthen due to climate change (KM 14.4; Figure 8.2).
Wildfire risk disproportionately disrupts the lives of socioeconomically disadvantaged communities in the Southeast.2 As more people inhabit forested areas, there is an attendant increase in wildfire risks to human health and property.255 More hot days may also exacerbate soil moisture deficits, leading to heightened wildfire risk in the region.244,256 Rural, mountainous portions of the Southeast are more exposed to and less equipped for mitigating wildfire.257
Forest managers conduct controlled, low-intensity fires, known as prescribed burns, to reduce the amount of deadwood and vegetation, thereby managing wildfire risk.258 While the impacts of wildfires on air quality are widely recognized (KM 14.2), less is known about the impacts of prescribed burns versus wildfires on air quality.246,259 Prescribed burns reduce the risk of wildfire damage to the environment, homes, and infrastructure, although areas with intensive prescribed burning tend to be near communities with higher social vulnerability scores, which subsequently experience more negative health outcomes from the smoke.260,261 As conditions favorable for wildfire and unfavorable for prevention become a greater risk for southeastern communities due to a warming and drying climate,256,262 communities may need to invest in more robust equipment and infrastructure. In 2016, wildfires in western North Carolina and eastern Tennessee highlighted the connection between exceptional drought and fire in the Appalachians.263 Power outages and damage to PVC pipelines that supplied water to sprinkler systems led to a lack of water to combat fires, resulting in more significant damages.264,265 That year, nearly 50% of US wildfires occurred in the Southeast, yet these fires contributed to only 29% of the total area burned that year, indicating that southeastern wildfires are smaller.244,246,258
Harmful algal blooms (HABs), also known as red tides or brown tides, occur in fresh, brackish, and salt water.266 HABs result from the overgrowth of algae due to runoff water containing excess nutrients from agriculture and lawn maintenance, rising water temperatures, and other land-use development.267 Since 2011, large masses of sargassum, which can fall under a HAB classification, have been increasing from Florida across the Caribbean, causing harm to coastal social–ecological systems. This problem could be intensified by rising temperatures from climate change.268,269 HABs have significant negative impacts on human and animal health, as well as broad-reaching environmental and economic effects.270,271,272,273
Humans may experience various health issues from HAB exposure, such as diarrhea and headache.273 HAB events also threaten national and local economies, as tourist areas become less desirable to visit.271 Fisheries and aquaculture industries suffer from the loss of marine life and decreased species diversity as ecosystems are disrupted and hypoxic conditions occur,274,275,276 and consumers are potentially exposed to seafood poisoning.277,278 On Florida’s Gulf Coast, prolonged algal events have caused a devaluation of coastal properties.270,272
Temperature and precipitation changes are anticipated to shift the geographic distribution and season of certain disease-carrying mosquitoes and ticks in the Southeast (KMs 15.1, 8.2). For ticks that carry diseases such as Lyme and Rocky Mountain spotted fever, models project varying shifts in ecosystem suitability in the Southeast depending on the species, land-use changes, and host abundance.279,280,281,282,283 Of particular concern are mosquito-borne diseases such as chikungunya, dengue, malaria, West Nile virus, and Zika virus. All have been documented in the Southeast and pose potential risks to human health.284 Black and under-resourced neighborhoods in Chatham County, Georgia, were identified as hotspots for West Nile virus, as well as being home to communities with limited understanding of personal risk and protective measures against mosquitoes.285,286
The Southeast is home to 5 out of the 10 highest-ranked states for the prevalence of mental illness287 and 8 out of the 10 lowest-ranked states for access to mental healthcare services.288
Climate change significantly affects mental health as a result of 1) acute disaster events such as hurricanes, floods, and wildfires (KM 15.1); 2) long-term changes such as drought289 and heat stress;210 and 3) existential threats of long-lasting climate change impacts that make people feel less secure in their physical environment.290 Those who are either directly impacted by or concerned about the threat of climate change to themselves or others may experience “eco-anxiety” or “climate anxiety.”291,292
While extreme weather events commonly occur in the Southeast, climate change has increased their frequency and magnitude (Ch. 2), causing residents to face repeated trauma and displacement at an unprecedented level, which can lead to stress and the onset of new psychiatric disorders or the worsening of preexisting mental health conditions,293 especially among children and under-resourced and BIPOC residents.290,294,295 The Florida Department of Health in Monroe County conducted an evaluation of its emergency shelter effectiveness in serving people with particular access and functional needs and found significant room for improvement, leading to updates to strategic planning processes and procedures related to the operation and communication of specialty emergency shelters to ensure more equitable access to shelter services.
Over the last few decades, economic growth in the Southeast has been concentrated in and around urban centers (high confidence) that depend on climate-sensitive infrastructure and regional connections to thrive (medium confidence). Simultaneously, rural and place-based economies that rely on the region’s ecosystems are particularly at risk from current and future climate changes (very likely, high confidence). Global warming is expected to worsen climate-related impacts on economic systems, labor, and regional supply chains in the Southeast, with disproportionate effects on frontline communities (very likely, high confidence). A coordinated approach that recognizes present-day inequities and the interdependencies between rural and urban communities will be necessary to secure the region’s economic vitality (very likely, high confidence).
Across the Southeast, disaster losses have increased over the last several decades, primarily due to rapid growth in hazardous areas that are driven, in part, by national, state, and local policies that incentivize development in such areas.166,296,297 Rising disaster costs negatively impact local and regional economies, some of which are already affected by limited upward economic mobility for their population, as well as by limited administrative, institutional, and social capacity (Figure 22.12). Moreover, these multisectoral impacts are expected to worsen substantially due to climate change,298 especially in the Southeast region (Figures 22.13, 22.14, 19.1; KM 19.1).
Losses attributed to climate change are expected to increase as rapid development continues to occur in hazardous areas, particularly along coasts (Figure 22.4b),299 while rural residents face increasing levels of isolation and economic decline (Figure 22.12).62
Place-based economies that are located in hazardous areas and are reliant on unique ecological systems (e.g., aquaculture, farming, and recreation/tourism) face numerous challenges, including the uncertainties associated with the stability of freshwater and saltwater ecosystem services that support business and cultural attachment to place.301 For example, some fishing communities are facing threats to fishing infrastructure due to sea level rise and more intense coastal storms, as well as threats to fisheries stock habitats that are vulnerable to the effects of a changing climate, such as increasing bottom-water temperatures.142,302,303 Meanwhile, inland towns and cities with ecotourism attractions also face significant economic losses due to increased flash flooding,73,108 including lower-income rural areas in Appalachia, as exemplified by the 2022 floods in eastern Kentucky. Rapidly growing urban centers in the Southeast are increasingly vulnerable to drought and the challenges tied to the provision of water for residents and businesses.304,305,306,307 The Southeast is more drought-prone than other parts of the eastern US due to higher rates of evapotranspiration.308,309 Evapotranspiration is expected to increase due to future climate warming (Ch. 2). Alabama cities’ drought plans were evaluated as less comprehensive and lacking pre-drought preparation compared to those of California cities.152 In rural, agriculturally dependent economies, increased heat, drought, and water-laden tropical storms currently threaten the productivity of crops and livestock (KM 22.4),310,311 as well as the health and livelihoods of workers, who tend to be Latino migrants.312 Future global warming will increase this threat, potentially further reducing labor productivity and costing billions of dollars, particularly in the already hot and humid Southeast (KM 2.2).212,313 The Southeast’s economy relies on the region’s ports, rivers, rail, air, and road networks, which are at risk from sea level rise, flooding, extreme heat, drought, and other climate-related hazards.61,314 However, proactive adaptation can offset potential future climate-related damages substantially (Figures 22.13, 22.15, 22.17). Unplanned disruptions to these systems can potentially affect consumer pricing of goods, services, and livelihoods throughout the region and elsewhere (Figure 22.16).315,316
There is an urgent need to address climate change risks to global supply chains (Focus on Risks to Supply Chains; KM 19.1).318 In the Southeast, climate change–induced transportation infrastructure risks affect all modes (e.g., air, water, highway, rail, and even pipelines; Figures 22.15, 22.16; Ch. 13). Transportation agencies across the region appear to be planning for infrastructure improvements on different schedules and often lack the capacity to include climate data in the planning process (Ch. 13).319 Coordinated and proactive adaptation strategies could offset significant future damage to these systems (Figures 22.15, 22.17).317,320,321
Many Southeast roadways and rail lines are located along waterways and frequently cross bodies of water, making them vulnerable to potential floods and heat-related impacts. High future costs are expected if no adaptive investments are made today (Figures 22.15, 22.17).317 Inland navigation and the Mississippi River are critical to supply chains in the Southeast and much of the central portion of the United States, as evidenced by the 2021 closure of the Interstate 40 bridge over the Mississippi River at Memphis, Tennessee.322 Unscheduled lock outages resulting from floods, droughts, earthquakes, or hurricanes can cause cascading impacts. For example, an unplanned outage of the Calcasieu Lock in southern Louisiana would affect economies in 170 counties and 18 states (Figure 22.16).315,323 In the Southeast, manufacturing facilities for industries such as automotive (including electric vehicles and charging stations),324 solar panels, agriculture,325 and construction often rely on parts or materials originating from other locations, including some from international sources. The Mississippi River serves as a gateway to the Nation for imports of such materials and exports of goods such as agricultural products. In recent years, low-flow conditions due to regional droughts on Southeast waterways such as the Mississippi have halted or delayed the movement of barges carrying bulk goods, with regional and national implications (Figures 22.14, 22.16).326,327
Disruptions can impact not only the delivery of finished goods and products to customers but also production and the livelihoods of individuals working in jobs dependent on materials from other locations that may not arrive in time, leading to revenue loss and even potential job loss if disruptions become regular and significant enough. The impacts of climate change on supply chains include not only disruption to systems and additional costs associated with the transportation of goods but also potential health impacts to workers in industries that require working outdoors, such as agriculture,325 fisheries, construction, and last-mile delivery,328,329 who may be exposed to extreme heat or cold. Workers in these jobs may require additional heating or cooling or adjustments in shift times to avoid exposure to adverse weather conditions (KM 22.2; Ch. 19).330
Furthermore, the Southeast is a hub of activity for oil refineries that provide fuel to the eastern half of the United States.331 Climate change is expected to negatively impact not only refineries that are located along the Gulf Coast but also the distribution networks of the petroleum products that many rely on for emergency services, backup power generation, air travel, and more.60,332,333
Protecting businesses and urban and rural infrastructure investments may require adopting a combination of adaptation measures (KM 22.1). However, to avoid unintended disparities in service provision, these infrastructure investments should consider the needs of frontline communities in their design criteria.334 For instance, Charleston, South Carolina, has explored questions surrounding the appropriate selection of adaptation measures, including protection techniques such as a seawall versus a greater reliance on nature-based solutions.
Justly transitioning to a low-carbon economy provides opportunities for businesses335 as well as labor,336 assuming that marginalized populations and women are included in this workforce to avoid the inequities of our current energy labor markets.337 Business and governmental agencies could commit to workforce programs for employees in the oil, gas, and coal-producing industries,336,338 as workforce training in green technology must address challenges associated with transitioning away from economies that are closely tied to a community’s way of life.339,340 Additionally, ecosystem restoration and nature-based green infrastructure solutions (e.g., urban forestry, stormwater retention gardens, green roofs) may also provide meaningful job opportunities (Ch. 19).341 Key to adapting to climate change and leveraging new opportunities is the need for training and workforce development, which will require investment and prioritization (Ch. 19).
Changes in temperature, drought, extreme rainfall, and sea levels are already threatening the Southeast’s agriculture and other food-related systems (likely, very high confidence). Moreover, these climate-related hazards are expected to worsen with every increment of global warming, disproportionately harm farmers and small-scale operations, and increase the competition between urban and rural communities for valuable resources such as water and land (high confidence, very likely). However, innovative agricultural techniques such as precision farming show promise for adapting to future climate changes in the region (likely, high confidence).
Agriculture is critical to the economy of the Southeast through its production of food and fiber and employment. In the United States as a whole, agriculture, food, and related industries contributed $1.26 trillion (in 2022 dollars; a 5.2% share) to the gross domestic product in 2019.342 In the Southeast, nearly 500,000 farms produced market sales of more than $83.8 billion (in 2022 dollars),343 and the region’s agricultural products are consumed locally and exported throughout the United States and the world.344 Food systems distribute agricultural products throughout the region, although food deserts are present in urban and rural areas.345 Disparities in food distribution are especially pronounced in areas with concentrations of Black, Indigenous, and under-resourced communities.345
Climate change stresses agriculture and food systems (Ch. 11). Threats from a changing climate include both direct threats through impacts of climate extremes on crops, forests, ecosystems, and livestock and indirect threats through impediments to transportation, the health of outdoor workers and animals, degradation and loss of natural ecosystems, reduced productivity and loss of traditional crops, increased threats from invasive species and weeds, and loss of livelihood for vulnerable communities such as rural BIPOC farmers. For example, increased average and extreme high temperatures346 have led to increased heat stress on livestock325,347 and outdoor workers. Warmer winter temperatures have reduced the number of chill hours (the total number of hours a plant experiences temperatures below 45°F over the winter months), which are essential for fruit production,348 and have caused unusually early blooming of crops such as peaches and blueberries, which makes them vulnerable to damaging frost events. In spite of warmer winters, however, the change in the average date of the last spring frost is not consistent across the region.349
Higher temperatures, particularly overnight temperatures, have reduced crop yields,350 and these impacts are projected to worsen with additional global warming (Figure 22.19; Ch. 11). They have also led to an increase in the occurrence of drought in the region (Figure 22.18).351,352,353 The Southeast is the only region in the eastern half of the United States that is prone to extreme drought,308 and flash droughts occur with higher frequency there than in any other region.354 Longer-term droughts in the Southeast appear to be increasing in severity but do not appear to be occurring more frequently.355 Changes in climate conditions have also contributed to increased pressure by invasive species that have resulted in crop yield losses and damaged productive natural ecosystems.356,357 Increases in the frequency of heavy rain events358 and lengthening of dry spells between rain events at some locations in the region359,360,361 make water resources unpredictable. Hurricanes and tropical storm winds, as well as increasing accumulated rainfall in coastal areas, pose unique threats to agriculture.92,362 For example, following Hurricane Florence, swine feces markers were detected in surface waters in North Carolina, suggesting that management practices should be examined in areas at risk of increased extreme precipitation.363 Rising sea levels have increased saltwater intrusion in coastal aquifers, reducing the extent of available forests and farmland130,131 and threatening seafood harvesting in estuaries by altering the salinity and turbidity in freshwater streams and marine nurseries.364 Extreme weather and coastal stressors have also disrupted food distribution by closing ports and highways,365,366,367 reduced the catch of fish, and diminished crop production.140
Climate stressors such as drought have a disproportionate impact on small-scale, Black, Indigenous, and economically disadvantaged farmers, who are more concentrated in the Southeast compared to other NCA regions (Figure 22.18).368,369,370 These groups are under-resourced, making adaptation to climate change more difficult.371 Knowledge gaps in best practices for small-farm management complicate information-sharing among communities across the region. Access to broadband in rural areas may limit producers’ ability to monitor their fields and make appropriate management decisions.372,373 Small-farm owners also have limited financial resources, which means they have less ability to invest in necessary farm equipment, insurance, and other risk-reduction methods such as irrigation that could mitigate climate stress and reduce farmland value losses.374,375 Small-scale farmers and those with limited resources may find targeted USDA programs as well as innovative techniques such as organic farming and agroforestry to be well-suited to use on their smaller farms in the future.376,377
Southeastern agriculture and food systems are further stressed by land, water, and resource competition between urban and rural areas.378 Competition is highlighted by decades of lawsuits in the Southeast involving the appropriate distribution of water resources among municipal water users in large cities, agricultural producers using irrigation to protect against drought, and coastal fisheries that rely on balanced salinity levels to maintain the health of estuarine systems.379 Sprawl is expanding into farmland, reducing the land available for food production and increasing the area affected by urban heat islands.380 Similarly, native forests have been developed or replaced by commercial forests, which may lack biodiversity and ecosystem resilience.381
Climate stressors in other regions can have cascading effects on the Southeast and in turn the entire United States. For example, sea level rise is expected to hinder the operation of ports where food, other agricultural products, and other needed supplies are imported and exported (KM 22.3). Additionally, low and high flows from droughts and floods may hamper the movement of food and agricultural products within and through the region, especially in highly urban and rural areas.382,383 Climate extremes can also reduce crop yields elsewhere and thus the availability of food products for the Southeast, potentially increasing stress on under-resourced populations through cost hikes and decreasing access to nutritious food.384,385
Agricultural producers are using various techniques to respond to increased climate stress, which is expected to result in decreased crop yields in many parts of the Southeast (Figure 22.19).300 Precision agriculture can minimize water use through the timely and appropriate irrigation of crops based on growth stage and soil moisture.386 The use of cover crops to preserve soil moisture and nutrients reduces the impacts of soil erosion and the leaching of nitrate into waterways and coastal estuaries, as well as the need for expensive inputs of fertilizer and irrigation water (Ch. 11).387,388,389 Other innovative agricultural techniques such as organic farming, advanced grazing management, silvopasture, agroforestry, and other agroecological systems (Box 22.3) also show promise for adapting to future climate changes in the region through a reduction in emissions of greenhouse gases and increased carbon sequestration in the soil and vegetation.376 New crops such as olives and satsuma citrus have been introduced to some areas to take advantage of the shifting plant hardiness zones and favorable market value of the crops.390,391,392,393 Genetically modified organisms and new cultivars of perennial crops can contribute to reduced emissions of greenhouse gases through reductions in fieldwork and may reduce the need for inputs such as pesticides, as well as provide additional resilience to expected increases in temperature and drought that may threaten long-term yields.394,395,396 A longer growing season also allows some producers to grow two crops in a year instead of one, reducing the likelihood of a weather catastrophe destroying a year’s harvest in a single event.397
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Author selection for the Southeast chapter began with assessing the geographic distribution, career level, and academic expertise of the individuals listed in the Federal Register Notice nomination list. The chapter lead author (CL) then also assessed a number of other characteristics including demographics and previous experience with National Climate Assessment (NCA) chapter development. Initial invitations were sent following US Global Change Research Program (USGCRP) guidance. The CL extended multiple rounds of invitations until the final list of authors for the Zero Order Draft (ZOD) was complete in February 2022, achieving a distribution of career stages, expertise, and geographic representation. Additional authors were added after ZOD reviews from USGCRP agencies were assessed. Author team meetings were held virtually and were used primarily to gather consensus on the direction of the chapter content. In preparation for the public engagement workshops that were held in January and February 2022, the author team worked through the format of the engagement and how feedback would be gathered and summarized. The CL also gathered ZOD feedback from regionally focused organizations: the Southeast Sustainability Directors Network (January 18, 2022) and the Southeast and Caribbean Disaster Resilience Partnership (January 26, 2022), as well as a youth-focused event put on by the Youth Environmental Alliance in Higher Education (February 15, 2022).
Subsequent drafts of this report reflected changes and edits agreed upon by a simple majority of authors in response to several dozen comments and suggestions from public, National Academies, and USGCRP Agency reviews. Consensus on chapter-wide changes was usually unanimous, with very few changes needing considerable discussion. The largest changes to the chapter occurred during the drafting of the Fourth Order Draft (4OD), as this was the draft that would need to respond to a large number of public and National Academies comments. Many of the changes would be instituted during the All-Author Meeting in April 2023. Review Editor Tisha Holmes ratified that the changes satisfied all public and NASEM comments before submission of the 4OD for Technical Support Unit editorial review.
Read about Confidence and Likelihood
Population growth and land-use change in the Southeast have been widely reported on in a variety of contexts, including in previous NCAs. This evidence has only gotten more detailed since NCA4.19
The relationship between global warming and increases in regional sea level trends has recently been substantially improved, allowing for highly detailed descriptions of future relative sea level and thus flood risks.51 Other advances related to projections of future rainfall intensity, duration, and frequency tied to both nontropical100 and tropical systems92 have greatly improved our understanding of future changes in the Southeast, including its potential downstream impacts on frontline communities.13,53
A wide body of quantitative research and qualitative practice has shown that the proactive adoption of risk reduction measures can significantly reduce future losses tied to natural hazards, including those exacerbated by a changing climate.154 Furthermore, there is widespread agreement that natural hazards and climate change is disproportionately impacting socially vulnerable populations.3 Planning and the distribution of funding have the potential to significantly reduce hazard risk, including that associated with climate change. However, the application of land-use planning techniques varies widely, and access to external grant funding is more often obtained by wealthier communities.16,17
Projections of future population are based on many assumptions. Research on how future land-use change will exacerbate particular climate stressors in southeastern cities and across the region could help inform the best use of interventions and application of growth strategies. There have been limited analyses of adaptation activities in the Southeast, data inputs used, and evaluation of impacts. Downscaling global climate change models to inform geospatially targeted adaptation tools and techniques at the neighborhood and parcel scale is improving. However, the use of this downscaled information requires continued refinement to improve accuracy; in addition, better processes for sharing this information would help local officials, including low-wealth jurisdictions with limited staff and technical expertise. There still exists uncertainty regarding how future intensification of storms will impact design standards, such as determining the appropriate design standard in an era of climate change, who makes these decisions, and who pays for the additional costs. These questions apply to housing, public facilities, and infrastructure. It remains uncertain how well communities are reducing hazard risk when accounting for both individual projects (which have been captured effectively in terms of future losses avoided) and ongoing development, which includes a variety of standards, ordinances, and public investments. There is limited literature estimating sub-daily precipitation metric projections for the Southeast. The degree to which future land use and urbanization will exacerbate or overpower climate change–intensified risks at the local level, especially in frontline communities, is under-explored in the current literature.
Population trends from the US Census Bureau are highly reliable through time and space, and as such, we ascribe very high confidence to reporting their data as well as future population estimates that virtually without exception agree on continued regional growth, warranting a very likely assessment. Risk management and assessment literature is extremely consistent on how sprawl and development relate to natural disaster risk, earning these statements very high confidence and likely assessments. That governance structures of varying scales are using outdated and/or limited information on climate-related risks is a well-reported feature within the flooding, disaster preparedness, and urban planning literature, so we assign high confidence to these statements. There is overwhelming consensus that climate adaptation efforts are concentrated in wealthier, more resourced communities, and therefore we assign assessments of high confidence and likely. There is overwhelming consensus that under-resourced, older, and marginalized communities are at higher and increasing risk from present and future climate extremes, although the risk in rural areas is less fully assessed quantitatively, thus resulting in our assignment of high confidence and likely.
There is strong evidence and consensus that climate change is already affecting the health and well-being of populations in the Southeast.19 There is also strong evidence and consensus that climate-related environmental health stressors are projected to worsen.19
There is evidence that residents in the Southeast have poorer health in general compared to other US regions196 and have limited access to healthcare resources.202,288
It is well established that there are preexisting inequities in health and healthcare access, safe and affordable housing, and access to resources to adapt to climate change, and that these inequities are associated with communities with a high proportion of under-resourced and BIPOC (Black, Indigenous, and People of Color) residents.3,12,202,220
The occurrence and projection of more frequent and intense extreme heat events are well documented by temperature models of the Southeast.3,230,231 The literature assesses the disproportionate health impacts of heat on those most affected, including people who work outdoors,212,213 student and nonstudent athletes,214,215,216 and those who do not have adequate housing or cannot afford the energy costs of air-conditioning their homes.218,220,222
The literature outlines the causal pathway of how climate change is compromising air quality in the Southeast as a result of increasing favorable conditions for wildfires,244,245,246,256,262 longer and more intense pollen seasons,253,254,407 and increased production of smog,241,242,243 as well as the subsequent health impacts. There is some evidence that warmer temperatures are associated with an increase in harmful algal bloom events,267 which occur in fresh, brackish, and salt water, commonly occur in coastal areas in Florida, and can have detrimental effects on ecosystems, affecting plant, animal, and human health.273
The literature has established that climate change broadens the geographic distribution and season of certain disease-carrying mosquitoes and ticks, particularly in the Southeast, for tick-borne illnesses such as Lyme disease281,282,283 and mosquito-borne illnesses such as West Nile virus and Zika virus.284
Mental health data have established that the Southeast ranks worst among all regions of the US in the prevalence of mental illness and access to mental health care services,287,288 which is of particular concern as extreme weather events occur more frequently and intensely in the Southeast, causing displacement and stress.293
The degree to which health will be affected by climate change and climate adaptations is uncertain, due to various compounding factors that can influence health effects. There are few studies that quantify the health impacts of climate adaptation interventions in the Southeast, so there is a limited understanding of effective public health strategies for addressing climate change.
Because there is limited data on pollen and vector-borne diseases in the Southeast, it is challenging to fully understand the impacts of climate change on these disease exposures.
There is also limited quantitative data on the mental health impacts of climate change. This information tends to rely on survey data, qualitative data, and anecdotal information.
There is a high degree of agreement in the scientific literature that climate change will impact and is already impacting extreme temperature and precipitation events, air quality, water quality, the spread of vector-borne diseases, and the prevalence of algal blooms, all of which have an impact on the health of people in the Southeast, as evidenced by health outcome information including health impact assessments of recent events, health projections of future events, and environmental health trends in the Southeast. Based on this information, the authors assigned very high confidence that the changes in temperature and precipitation due to climate change, in conjunction with changes in air quality, water quality, the spread of vector-borne diseases, and the prevalence of algal blooms, will impact, and is very likely already impacting, the health and well-being of people in the Southeast.
It is well established that the conditions in which people live and work have an impact on health, which is understood as the social determinants of health. It is also well established by the literature and lived experience that marginalized populations will experience disproportionate health impacts, as that is seen consistently across public health and particularly in environmental health. For this reason, as well as because of the breadth of literature on the disproportionate impacts of climate change on the health of marginalized populations, the authors assigned very high confidence that community characteristics such as racial and ethnic population, chronic disease prevalence, age, and socioeconomic status, can influence how climate change exacerbates, ameliorates, or introduces new health issues, widening the gap in health status.
Based on models of health impacts under varying climate scenarios, it is well-established that lower emission scenarios will result in less severe health outcomes. The literature is less established on the health benefits of climate adaptation efforts, as there is not a breadth of literature or evaluations on this topic, although from the literature that is available it is apparent that climate adaptation actions can improve health. For this reason, the authors assigned high confidence that climate mitigation and adaptation efforts can save lives and reduce the public health burden of climate change, particularly around reducing air pollutants and targeting already-marginalized communities, which is where the literature is more established.
There is a rapidly growing literature presenting both qualitative and quantitative evidence that livelihoods across the Southeast are already being impacted by climate change in a variety of important ways (Ch. 19),298 including place-based economies such as construction, tourism, and agriculture and aquaculture (e.g., fisheries are being impacted not only by significant hurricanes but also by geographical shifts among species in ocean waters),408,409 as well as systems like transportation infrastructure317 and electrical grid infrastructure320 that undergird the distribution of goods and services in these places. Extreme weather-related disruptions and adverse working conditions created by climate change can affect both people and infrastructure systems that support local and regional economies by impacting the local community as well as regional and global supply chains.326,327 References and figures included in Chapter 19 were instrumental to establishing author team consensus around key statements related to economic impacts being relatively larger in the Southeast than in other NCA regions.
Localized impacts on inland agriculture and tourism are not fully understood to date. The relocation of individuals and households away from climate-affected areas to other locations and their need to establish new livelihoods are not well understood, nor is the effectiveness of federal funding to support the construction of new settlements in less hazardous areas. The degree to which small and midsized businesses are adapting to climate change–related threats remains uncertain. The extent to which climate changes will impact large-scale agriculture is fairly well established, but the fiscal impact on small-scale family farms is not as well understood. There is limited research on the low-flow conditions and projections related to drought and its impacts on the Mississippi River and its tributaries as well as on the potential impacts to economies, despite how disruptive the events are to the regional, national, and global economy.
Based on the author team consensus reached through evaluating the evidence base presented in the literature as well as through direct and related experience in recent extreme weather and climate events impacting the Southeast, the authors have assigned high confidence to the statements surrounding the concentration of economic growth in urban centers, the climate-related risks to place-based economies that rely on ecosystems and to southeastern economies and labor, and the need for coordinated strategies to prepare for the shocks and stressors of the future. Medium confidence was assigned to the evaluation of the extent to which urban centers depend on the interregional connections to more rural places and other urban centers due to limited peer-reviewed literature in this area. While there are reports and white papers on this subject from nonprofits and research think tanks that largely agree on the potential for disruptions to these systems to have impacts on both rural and urban centers, limited peer-reviewed studies seeking to isolate urban/rural dependencies in the face of climate change support at least medium confidence. Projections of future climate impacts in the Southeast are particularly robust in their evaluation of future heat and extreme precipitation risks; we assign very likely and high confidence to our Key Message statements that seek to link climate impacts to economic outcomes in the Southeast. Chapter 19 (Economics) was especially helpful in establishing our very likely and high confidence assessments.
Evidence of trends in temperature, precipitation, and growing season are well documented in sources such as the NOAA National Centers for Environmental Information’s Climate at a Glance Tool and in the scientific literature.346,350 This literature base is extensive and covers individual states, the Southeast region, the United States, and the globe. Earlier concerns about temperature trends from satellite observations, which did not match surface-based observations, have largely been resolved by improved calibration of satellite measurements.
Trends in precipitation show changes in both amount and temporal and spatial distribution that are more difficult to separate out due to the nature of precipitation in the Southeast and its ties to sub-grid-scale processes like convection and tropical systems.358,359,360,361 Evidence of trends in drought are less certain because of the combination of interacting contributions from temperature, precipitation variability, and soil characteristics, but are becoming more apparent in recent modeling efforts that are documented in the scientific literature.351,352
The impacts of climate variability and change on agricultural production have been well documented in the scientific literature in agricultural journals in recent years.350,356 More work is ongoing as better methods for collecting in-field measurements are used to fine-tune the relationships between plant physiology and climate variables.
The assessment of the impacts of climate change on the health of workers and livestock, transportation pathways for agricultural production, and economic losses to both large-production farmers and small BIPOC farming communities has increased greatly in the last four years and is being reported in scientific journal articles in health, infrastructure, economic, and other social science–oriented journals.325,347
Many examples of agricultural producers implementing climate adaptation in farming exist, suggesting a willingness to address the impacts of a changing climate across diverse land ownerships.
There is significant uncertainty regarding the ability of crop species to keep pace with changes in climate (based on temperature and precipitation), although plant breeders have a long history of producing new hybrids that can improve responses to changing climate conditions. The ability of new crops to be productive in an altered climate is also uncertain due to concurrent changes in temperature, precipitation, humidity, and soil characteristics, which interact with plant growth patterns. This leads to considerable uncertainty in the extent to which changes in crop choice and management can adapt to the future climate.
There is also uncertainty in the knowledge of carbon interactions between soils and crops, but numerous studies are underway to better document these interactions to improve future predictions.376
Since agriculture is a global endeavor, changes in market pricing and availability of inputs such as fertilizer, as well as outputs such as crop variety and yield, interact in a way that hinders the prediction of future agricultural outputs, droughts, and the economic effects of agricultural sales.410 As a result, economic impacts on both large-scale farmers and economically disadvantaged farmers with small-scale operations are difficult to predict with high confidence.
Based on the high degree of agreement in agricultural and climate science journal articles in the scientific literature and assessments of recent events, there is very high confidence that the interactions of warming temperatures, precipitation changes, sea level, and drought with insect pests, invasive plants, and plant pathogens are already threatening the region’s agriculture and food-related systems and will likely lead to decreased yields of many crops and production of other agricultural goods.356,357 Evaluations of recent past storm events coupled with the strong agreement in related journal articles resulted in an assignment of very high confidence that rising sea levels and impacts from tropical storms will disrupt coastal and port activities.325,347 Studies by social scientists published in the literature also demonstrate that small-scale BIPOC producers, as well as those who have limited financial resources, will be disproportionately affected by climate-related hazards;366,367 on that basis, the authors have described this as very likely with high confidence in the expected impacts. Additionally, based on examples in the scientific literature of adaptations that producers are already making in response to changes in the climate, the authors assigned a level of high confidence that producers in the Southeast will be able to adapt to those changes using techniques such as precision agriculture, changes in crop type, and innovative management of fisheries, livestock, and ecosystems, and a likelihood level of likely was assigned based on less agreement in the scientific literature about the degree to which they will be able to do so.386,390,394