Food, energy, and water systems are inseparable. Any change in demand for one will impact demand on the other two. The quality of life of the 34 million people residing in the Southern Great Plains is dependent upon the resources and natural systems for the sustainable provision of food, energy, and water. At least 60% of the region’s population is clustered around urban centers, which are experiencing population growth that exceeds that of rural communities. The remaining population is spread across vast areas of rural land.^{14,30,31,32,33} As the population in the region grows, rapid urbanization and economic development opportunities will drive an increase in the demand for food, energy, and water. Water is used in every aspect of agricultural production and electricity generation. Energy is required to extract and deliver water of sufficient quality for diverse human and agricultural use, as well as healthy consumption and wastewater treatment. Both water and energy are required to irrigate and process agricultural products and livestock to feed the region’s increasing population. The complex interdependencies at the food–energy–water nexus create enormous challenges.

When severe drought affected the Southern Great Plains in 2011, limited water availability constrained the operation of some power plants and other energy production activities. Contention for water developed between consumers associated with the food–energy–water nexus. The recent boom in domestic unconventional oil and gas development brought on by hydraulic fracturing and horizontal drilling represents another stressor to this nexus. This development has added complexity to the regional dialog about the relationship between food, energy, and water resources.

Superimposed on the existing complexities at the intersection of food, energy, and water is the specter of climate change. During 2010–2015, the multiyear regional drought severely affected both agricultural and aquatic ecosystems. One prominent impact was a reduction of irrigation water released for the Texas Rice Belt farmers on the Texas coastal plains, as well as a reduction in the amount of water available to meet instream flow needs in the Colorado River and freshwater inflow needs to Matagorda Bay. The Lower Colorado River Authority (LCRA), through its Water Management Plan (WMP), balances the needs of competing water demands in the Lower Colorado River Basin of Texas. Depending upon the amount of water stored in lakes, the WMP requires that LCRA reduce or cut off interruptible stored water for most downstream agriculture so firm water supplies are available to meet the basic needs of cities, businesses, and industries during drought.

In one year, planted acres of rice in Matagorda County, Texas, dropped from 22,000 acres to 2,100 acres.³⁴ The ripple effect on the local economy was severe, with a 70% decline in sales of farm implements and machinery. Some family-owned establishments that had survived for decades closed permanently.³⁵ Irrigation strategies shifted from river-based to pumping water from the Gulf Coast Aquifer, and dozens of new wells were drilled. Drilling water wells then resulted in declining groundwater levels, adding stress to water levels that had historically been falling in the region.³⁶ Some farmers attempted to adapt by making the difficult transition to other crops such as corn. However, when flooding rains inundated the region in 2016, 15% of the corn crop was swept away in flood waters.³⁷ Thus the 2010–2015 drought simultaneously affected agriculture, energy, recreation, and economic activity, eventually leading to increased groundwater development and potential future overexploitation. Projected increases in drought duration and severity imply even more pervasive direct and indirect effects. These impacts might have been even more severe had it not been for adaptation actions taken by the City of Austin, including implementation of drought contingency plans and water-use cutbacks in coordination with the City Council and community.

Climate change has significant negative impacts on agriculture in the United States, causing substantial economic costs (Ch. 10: Ag & Rural).^38,39 The effects of drought and other occurrences of extreme weather outside the Southern Great Plains also affect the food–energy–water nexus in the region. The neighboring Southwest region is especially vulnerable to climate change due to its rapidly increasing population, changing land use and land cover, limited water supplies, and long-term drought (Ch. 25: Southwest).⁴⁰ States in the Southern Great Plains import over 20% of their food-related items from Arizona, and El Paso, Texas, receives 25% of its consumable foods (mostly vegetables) and 18% of its animal feed supplies from Arizona.⁴¹ In addition, relationships across the border of the Southern Great Plains with Mexico will be critical to a better understanding of the food–energy–water nexus (see Case Study “Rio Grande Valley and Transboundary Issues”) (see also Ch. 16: International, KM 4).

The 2017 Texas State Water Plan⁵² indicates that the growing Texas population will result in a 17% increase in water demand in the state over the next 50 years. This increase is projected to be primarily associated with municipal use, manufacturing, and power generation, owing to the projections of population increase in the region. Likewise, the Oklahoma Water Plan indicates that water use projections in Oklahoma are expected to increase by 21% for municipal use, 22% for agricultural use, and 63% for energy use.⁵³ The Kansas Water Plan’s preliminary assessment of projected water demand in Kansas also shows an increase of 20%, but with the expected variability depending upon rural versus urban areas.⁵⁴ Throughout much of western Kansas, western Oklahoma, and the Texas Panhandle, groundwater from the Ogallala Aquifer is the dominant water source,^17,55 benefitting the agricultural sector in particular. This resource is known to be shrinking faster than it is replenishing, and some portions are likely to become an insufficient source or become completely depleted within the next 25 years, particularly at its southernmost extent.¹⁷ Drought more persistent than that experienced in the region’s recent history would trigger large social and economic consequences, including shifting agriculture, migration, rising commodity prices, and rising utility costs.²⁰

The importance of groundwater as a resource will increase under a changing climate as the intensification of hydrologic extremes decreases the reliability of precipitation, soil moisture, and surface water, and as surface water supplies are becoming increasingly over-allocated.^56,57,58

Research into the food–energy–water nexus is in its early stages and historically tends to examine only one or two components.^{59,60,61,62,63,64,65} It is clear that tradeoffs and cascading complexities exist between sectors, and changes in one sector are likely to propagate through the entire system (Ch. 17: Complex Systems). There are significant gaps in the scientific understanding regarding the role that climate change will play as a disruptive force and a threat to food, energy, and water security.^{60,63,66,67,68}

Climate change is anticipated to lead to higher average temperatures year-round and an increase in the frequency of very hot days (days with maximum temperatures above 100°F), with the number of such days possibly doubling by mid-21st century (Figure 23.4).⁸⁰ An increase in temperatures is virtually certain for the Southern Great Plains. Longer, hotter summers will place strain on cooling systems and energy utilities, road surfaces, and water resources, particularly during drought, although warmer winters are likely to reduce heating demands and winter road maintenance costs. The rate of temperature rise will be especially large within urban centers due to possible intensification of the urban heat island (UHI) effect, although the degree of heating will likely vary by city, and it is difficult to obtain precise quantitative estimates. Warmer temperatures will likely lead to an increase in evaporation and therefore an increase in moisture in the air^81,82 and an increase in heat stress, especially during the summertime.⁸³ During excessive heat in July 2011, downtown Dallas experienced late-evening temperatures 6.1°F higher than rural Kaufman, Texas, 36 miles away.⁸⁴ Population growth, increased urban density, and expansion will intensify the UHI effect for many Southern Great Plains cities, necessitating more energy use for cooling. This strains energy utilities and can further enhance the UHI effect.⁸⁵ If prolonged power failure occurs during high heat conditions, the impact to human health and comfort is projected to be notably more detrimental in a warmer climate.⁸⁶

Increased aridity (or dryness) is also projected for the Southern Great Plains with climate change, due to enhanced evapotranspiration and depleted soil moisture associated with increased temperatures.^1,29 In the past, drought conditions have decreased surface water availability (such as from reservoirs), leading to an increase in the use of groundwater. In some cases, new pipelines were needed and water had to be imported.²⁰ Compounding infrastructure challenges for the region include aging and over-capacity water pipelines.⁵³ The Texas Water Development Board⁸⁷ projected that by 2060, municipal water use will increase to 41% of available supply (versus 9% in 2010). Therefore, a record drought scenario occurring in 2060 would result in as much as half of the state’s population facing a water supply shortage. Additionally, water infrastructure can be damaged by drought. During summer 2011, water main breaks were common, with 200 breaks in Fort Worth, Texas, in one month and over 1,000 in one month in Houston, Texas,²⁰ associated with shrinkage of clay soil, a common soil type throughout the Southern Great Plains. Soil shrinkage can damage both surface and subsurface infrastructure, including roads, water and sewer lines, and building foundations. Periods of abundant precipitation followed by drought and high temperatures are also linked to increased wildfire activity in the region.⁸⁸ Texas experienced several major wildfire outbreaks during the drought of 2011, including the Bastrop Fire that destroyed more than 1,500 homes. More recently in 2016 and 2017, fires in Kansas and Oklahoma have exceeded 400,000 acres and were among the largest in the region’s history. These events killed thousands of cattle, contributed to several human fatalities, and damaged, displaced, or isolated rural communities.⁸⁹ Model simulations indicate that wildfire risk will increase throughout the region as temperatures rise, particularly in the summer, and the duration of the fire season increases.⁹⁰

Following the abrupt end to the persistent drought in 2015, the region suffered extensive damage associated with river and flash flooding.^10,91,92 Precipitation totals for a 120-day period during the spring of 2015 in south-central Oklahoma were above 40 inches, approximately the average annual amount in many locations,^93,94 largely associated with multiple episodes of very heavy rain. Numerous state and U.S highways experienced regional detours or closures.⁹⁴ A rockslide on Interstate Highway 35 closed portions of the road for several weeks.^94,95 Flooding in Oklahoma and Texas caused an estimated $2.6 billion in damage in 2015,⁹⁵ with $1 million in emergency relief funds provided by the U.S. Department of Transportation’s Federal Highway Administration to assist in the repair of damaged roads.⁹⁶ The increasing frequency of extreme precipitation that is projected by climate models is anticipated to contribute to further vulnerability of existing highway infrastructure, although the magnitude and timing of projected precipitation extremes remain uncertain.¹

Changing precipitation frequency and increases in the magnitude and frequency of heavy precipitation will place more stress on existing water resource infrastructure. The region has a large number of older dams and levees, many of which have received poor grades from the American Society of Civil Engineers.^16,17,18 Between 1982 and 2012, 82 dams failed in Texas, and during 2015 the high-hazard Lewisville Dam was of concern due to observed seepage.^18,97 As climate conditions continue to change, rare events such as 100-year floods (those that currently have a 1% chance of occurring in any given year) are likely to become more common.^1,29 Future extremes may exacerbate flooding and wear and tear on existing flood control infrastructure and will necessitate revisions to design standards for flood infrastructure and a reevaluation of floodplains. Floodplain management and mitigation of flooding are currently left largely to local governments and cities and are thus reliant on local funding and resources for successful implementation.^16,17,18 While there are clear implications of more variable and extreme precipitation on infrastructure, the precise links between specific events and their resulting damage are uncertain as most infrastructure is exposed to both climatic and non-climatic stressors whose effects are difficult to separate without a high degree of monitoring.

As the energy industry undergoes, to some extent, a reinvention, it is taking climate and extreme weather events into consideration in design, operations, and reliability. An Edison Electric Institute (2008) study estimated that by 2030, the U.S. electric utility industry will need to make a total infrastructure investment of between $1.5 trillion and $2.0 trillion, of which transmission and distribution investment is expected to account for about $900 billion.⁹⁸ These investments increasingly include renewable energy and distributed generation, smart grid technologies, and storage. From 2008 to 2013, the amount of electricity generated from wind has more than tripled and the amount from solar has increased more than tenfold.⁹⁹ These enhancements would need to be reliable (able to operate within limits so that instability, uncontrolled events, or cascading failures do not result if there is a disturbance), resilient (able to adapt to changing conditions and withstand and rapidly recover from disruptions), safe, flexible, and affordable.

Coastal regions are among the most vulnerable to climate change due to their direct exposure to rising sea levels and damaging storm surge. Global mean sea level is very likely to rise by 1–4 feet (0.3–1.3 m) by 2100 relative to 2000 levels. Under certain future conditions, a rise exceeding 8 feet (2.4 m) by 2100 is physically possible, although the probability of such an extreme outcome cannot currently be assessed (Ch. 2: Climate, KM 4). Since the early 20th century, areas of the Texas coast have experienced sea level rise (SLR) higher than the global average, associated with extraction of both fossil fuels and groundwater.²⁵ Within Texas alone, 1,000 square miles of land is within 5 feet of the high tide line, including $9.6 billion in current assessed property value and homes to about 45,000 people. Sensitive assets include 1,600 miles of roadway, several hospitals and schools, 4 power plants, and 254 EPA-listed contamination sites (hazardous waste and sewage).¹⁰⁰ Up to $20.9 billion in coastal property is projected to be flooded at high tide by 2030, and by 2050, property values below the high-water mark are projected to be in excess of $30 billion, assuming current trends of greenhouse gas emissions.¹⁰¹ The coastline in the vicinity of Galveston and Texas City is also a critical oil refining and transport hub. SLR will affect numerous coastal assets, including residential communities, roads, waterways, and energy generation facilities, and move the risk of damaging storm surge well inland of present areas of impact. With 2 feet of SLR, cities such as Galveston and Corpus Christi will be exposed to more frequent flooding.^{100,102,103,104}

Disruption to coastal oil-refining facilities can cause cascading failures throughout the region, including fuel shortages and higher prices. Saltwater intrusion of aquifers has been observed in the Gulf Coast Aquifer, the second most utilized aquifer in Texas, which supports 8 million people. Although this was in part associated with heavy pumping,¹⁰⁵ the Gulf Coast Aquifer remains vulnerable to further saltwater intrusion resulting from SLR and storm surge exacerbated by climate change.¹⁰⁶

Due to the historical frequency of drought, water conservation activities are already recognized as important and encouraged in many municipalities. Common strategies include rainwater harvesting, encouraging improved residential water-use efficiency, water audits, and restricted water use in times of drought.²⁰ Other proactive measures currently in place in some communities aim to mitigate longer-term risks and involve wastewater treatment and reuse, aquifer storage and recovery, and desalination (see Case Study “Meeting Current and Future Water Needs in El Paso, Texas”).²⁰

The built environment is vulnerable to increasing temperature, extreme precipitation, and continued sea level rise, particularly as infrastructure ages and populations shift to urban centers. Along the Texas Gulf Coast, relative sea level rise of twice the global average will put coastal infrastructure at risk. Regional adaptation efforts that harden or relocate critical infrastructure will reduce the risk of climate change impacts.

Climate change is likely to require modification and updating of design standards in order to accommodate changes in risk that cannot be accounted for based on history. For example, in transportation design, these modifications might include changing the minimum and maximum temperature rating for binders used in asphalt roads to improve durability; structural modifications to bridges to meet the demands of higher summer temperatures; updating the data used for calculating flooding of dams and neighborhoods; restricting rail speeds during hot temperatures; and shifting timing of maintenance activities. Many technological solutions exist or are in development to build resilience to these climate-related challenges. However, the aforementioned stressors and budgetary challenges will continue to present notable challenges to adaptive capacity in the Southern Great Plains (Ch. 12: Transportation).

Many studies have documented economic impacts of climate change on different sectors in the United States).^{111,112,113,114,115} For example, predictive analyses estimate that climate change and coastal development will cause hurricane damage to increase faster than the U.S. economy is expected to grow. The number of people expected to face substantial damage will, on average, increase more than eightfold over the next 60 years.¹¹⁶ Although economic analyses for specific regions, sectors, and states in the Southern Great Plains are currently limited, active ongoing research is beginning to produce critical metrics regarding the socioeconomic impacts of climate change at regional scales.¹¹⁷

The role of economics is increasingly recognized as being critical for advancing the resilience of households, businesses, and local governments, and also for the broader economic adaptation of entire regions. Establishing economic resilience in a local business or a regional economy requires the ability to anticipate risk, evaluate how that risk can impact key economic assets, and build a responsive adaptive capacity. At the regional or community level, economic development practitioners can build capacity for economic resilience.

The Southern Great Plains encompasses diverse ecoregions (areas where ecosystems are generally similar) stretching from the High Plains to the Edwards Plateau and from the Tamaulipan Brushlands to the Gulf Coast Prairie.¹¹⁸ The region is prone to periods of drought punctuated by heavy rainfall events, with evidence that these events are occurring more frequently.¹⁰ These precipitation patterns influence water availability and aquatic habitats such as lakes, rivers, springs, and streams. Freshwater inflows from rivers flowing to coastal estuaries provide important nutrients and sediments while moderating salinities to create and maintain productive estuarine ecosystems.

Species Distribution and Habitats

Climate plays a key role in the distribution of species (Ch. 7: Ecosystems). Species’ response to climate change is complex and variable.¹¹⁹ As temperatures increase, the geographic distribution of some species tends to shift to areas with temperature ranges where a given species can survive. A notable species of concern in the region is the lesser prairie‐chicken, which was listed as threatened under the U.S. Endangered Species Act in May 2014. Currently, the lesser prairie‐chicken habitats include Kansas, Texas, and Oklahoma (as well as Colorado and New Mexico) with 70% of the population in Kansas.¹²⁰ At this time, it is not clear whether climate change will influence the lesser prairie-chicken in positive or negative ways.^121,122 Rising temperatures are also causing changes to growing seasons and migration patterns of birds and butterflies.¹²³ In Texas, white-wing doves, originally confined to the Lower Rio Grande valley, have been expanding northward¹²⁴ and are now common across Oklahoma. Other factors such as habitat loss also influence species distributions, making it difficult to pinpoint a single cause for these distribution changes.

While it is unclear how climate change will affect species directly, the effects of increased aridity will likely have negative impacts. In addition, ecosystem services—the materials and processes that ecosystems produce that benefit people—will also be affected.¹²³ In general, drought forces wildlife to travel farther to locate food, water, and shelter, which can deplete body condition going into winter or spring migration, when food sources are typically scarcer, making them more vulnerable to other stresses. The highly endangered Houston toad was negatively impacted during the 2011 drought and devastating wildfire in Bastrop County, Texas. Whooping crane numbers, which depend on sufficient freshwater inflows for a reliable food source (primarily blue crabs), were also reduced. In addition, a lack of freshwater can force whooping cranes to fly to uplands to drink, using more energy and exposing birds to more threats from predators and other mortality factors.

Aridification exacerbates stress in highly isolated habitats and fragmented lands, diminishing the ability for species to persist if they cannot move to better conditions. Migratory birds are better able to move to areas with better habitat conditions but could be in a weakened condition to do so. Migratory waterfowl can also be negatively impacted by reductions in wetland habitat areas due to aridification. Loss of irrigated rice fields in Texas contributed to significant declines in wintering waterfowl along the Gulf Coast. The most significant decline was documented for snow geese, with a 71% decline for 2011–2014 as compared to the long-term average.¹²⁵ Playa lakes in the High Plains serve as important habitat for migrating waterfowl, but during the drought these wetlands were virtually nonexistent.

Plant community changes are also occurring, possibly due to climate change and other factors, and these changes in turn affect fish and wildlife. In the Southern Great Plains region, winters are warmer and spring is arriving earlier. Along the Texas coast, black mangroves, which are sensitive to cold, are expanding northward along the coast, and red mangroves, formerly not found in Texas, are now appearing there.¹²⁶ Warmer winters with fewer freezes are also conducive to pests and diseases. Woody shrubs invading prairie grasslands are favored by increases in concentrations of carbon dioxide (CO₂), changes in soil moisture cycles, fire suppression activities, and soil disturbances.¹²⁵ The 2011 drought produced a direct and indirect tree mortality rate of over 6%—many times the normal rate.¹²⁷

Aquatic Ecosystems

Climate change impacts to aquatic ecosystems include higher water temperatures in lakes, wetlands, rivers, and estuaries that can result in lower dissolved oxygen, leading to more fish kills. Impacts to reservoirs include fluctuating lake levels, loss of habitat, loss of recreational access, increase in harmful algal blooms, and disconnectedness from upstream and downstream riverine habitats.¹²⁸ Localized declines in fish populations have been documented in rivers due to lack of water or water confined to increasingly narrow pools; in some cases, these declines prompted biologists to capture and relocate some endangered species to fish hatcheries.¹²⁹ Aridification (a gradual change to a drier climate) can have a number of negative impacts on freshwater mussel populations, including increased predation pressures, hypoxia (low oxygen conditions), increasing water temperature, and, ultimately, anoxia (no dissolved oxygen in water) or emersion (stranding the organism out of water and exposing it to air).

Coastal Areas, Bays, and Estuaries

The Texas coast, with 6.5 million people contributing over $37 billion to the region's economy, relies on its natural features, bays, and estuaries that serve as storm barriers to protect coastal infrastructure, and on its climate amenities to spur ecosystem services, such as fishing, ecotourism, and the ocean economy. These coastal ecosystems provide protection not only for people but also for 25% of the Nation's refining capacity, four crucial ports, much of the strategic petroleum reserves, and strategic military deployment and distribution installations. This protection was clearly on display with the recent impacts of Hurricane Harvey, where it has been estimated that natural coastal habitats protected about $2.4 billion worth of property in Texas and thousands of lives, with the suggestion that these habitats are potentially our first lines of defense.¹³⁰

A rising sea level impacts more than 74% of Gulf-facing beaches in the upper Texas coast. The average rate of beach erosion is almost 10 feet per year.¹³¹ Sea level rise means more frequent and longer-lasting flooding of marshes that eventually could be permanently flooded, becoming open water.^126,132 Higher tides and storm surges cause inundation of freshwater areas and beach erosion, leading to a potential decrease or loss of barrier islands and coastal habitats, including nesting habitats and submerged habitat such as seagrass beds affected by changes in water quality and changing water depths. A significant percentage of fishery species in the Gulf of Mexico are dependent upon estuaries for some portion of their life cycle.¹³³

The warming of bay waters on the Texas coast has been documented for at least 35 years. This mostly reflects warmer winters, not warmer summers. The increase in water temperature directly affects water quality, leading to the higher potential for low levels of dissolved oxygen, or hypoxia. Hypoxic events and harmful algal blooms have caused fish kills, leading to lower productivity and diversity of estuarine ecosystems.¹²⁶

Freshwater inflows are critical to both aquatic ecosystems and wetlands in the Southern Great Plains. Both surface and groundwater depletion have led to dramatic changes of the aquatic and wetland communities in Kansas¹³⁴ that not only impact inland species but have a dramatic effect on coastal species relying on the freshwater inflow to ensure the integrity of the coastal ecosystem. Whooping crane and many other migratory species flying through this region during both spring and fall are impacted.¹³⁵ Climate change and human use have impacted these aquatic systems and wetlands and, ultimately, the vital flow of freshwater to the coastal marshes and estuaries.

Changes to freshwater inflows to estuaries lead to changes in salinity and inflows of nutrients and sediment, resulting in impacts to oysters and other sensitive estuarine species. In addition, harmful algal blooms have become more frequent, more intense, and more widespread.¹²³ Reduced freshwater inflows during 2011 led to record high salinities in Texas estuaries that contributed to a coast-wide “red tide” harmful algal bloom event. Red tides, a type of harmful algal bloom, most commonly occur during drought years, as the organism that causes red tide does not tolerate low salinity. Red tide blooms cause fish kills and contaminate oysters. In addition, oysters and other shellfish can accumulate red tide toxins in their tissues. People who eat oysters or other shellfish containing red tide toxins become seriously ill with neurotoxic shellfish poisoning. Once a red tide appears to be over, toxins can remain in the oysters for weeks to months. The 2011 bloom started in September and lasted into 2012. Fish mortality was estimated at 4.4 million. The commercial oyster season was closed and disaster declarations issued. The total economic loss was estimated at $7.5 million (dollar year not reported).¹³⁶

Gray snapper have been ranging farther north since the 1990s; once found only in the lower Laguna Madre and off the extreme southern shore of Texas, they are now migrating northward along the upper Texas Coast. Conversely, flounder abundance has been declining due to the warmer winters,^137,138 since sex ratios (the number of males versus females) are influenced by temperature during flounder development and increases in temperature produce increasingly male-dominated sex ratios in southern flounder from Texas (See Figure 23.9).

Existing Options for Managing Risk

The National Fish, Wildlife, and Plants Climate Adaptation Strategy¹²³ was developed to provide natural resource managers and decision-makers the strategies and tools to address climate change impacts. The Strategy offers a guide for actions that can be taken in spite of remaining uncertainties over how climate change will impact living resources.

The Texas Edwards Aquifer Recovery Implementation Program Habitat Conservation Plan⁷⁸ balances water pumping and use of the aquifer with protection of eight federally listed threatened and endangered species that depend on San Marcos Springs and Comal Springs, two of the largest springs in the southwestern United States. These springs are the headwaters of the San Marcos and Comal Rivers and provide important water flow, especially during drought, to the Guadalupe River and Estuary.

Environmental flows—instream flows and freshwater inflows to bays and estuaries—are critical for sustaining aquatic ecosystems. In 2007, the Texas Legislature passed Senate Bill 3, which established a comprehensive, statewide process to protect environmental flows.¹³⁶ The process relies upon input from local stakeholder groups, composed of balanced interests ranging from agricultural water users to commercial anglers. The Texas Commission on Environmental Quality has adopted environmental flow standards intended to protect flow regimes that will help ensure healthy rivers, streams, and estuaries for Texas. The focus now is on adaptive management to refine standards, address research needs, and identify voluntary strategies to meet environmental flow standards.

The Texas Coastal Resiliency Master Plan¹³⁹ promotes coastal resilience, defined as the ability of coastal resources and coastal infrastructure to withstand natural or human-induced disturbances and quickly rebound from coastal hazards. This definition encompasses the two dimensions of resilience: 1) taking actions to eliminate or reduce significant adverse impacts from natural and human-induced disturbances, and 2) responding effectively in instances when such adverse impacts cannot be avoided. To keep pace with the dynamic Texas coastline, the Plan will be updated regularly to allow the state to continually assess changing coastal conditions and needs and to determine the most suitable way to implement the appropriate coastal protection solutions.

Extreme heat causes both direct and indirect impacts on human health and acts as a threat multiplier to the medically vulnerable. The increase in extreme heat due to climate change will exacerbate the medical issues associated with heat illness. More detail can be found in Chapter 14: Human Health. Notably, heat stress is strongly correlated with complications of lung disease, such as asthma and emphysema, as well as dehydration and injurious electrolyte abnormalities. It is estimated that each increase of approximately 1.8°F (1°C) in summer temperature increases the death rate for elders with chronic conditions by 2.8% to 4.0%.¹⁴⁰ During heat waves, concrete, blacktop, and the low ventilation capacity of urban “canyons” created by tall buildings can add 7°–12°F to the urban heat load.¹⁴¹ The heat wave of 2011 exemplifies the human health and healthcare system impacts of extreme heat in the Southern Great Plains. The average temperature in Texas from June to August that year was 86.7°F (30.4°C), which broke all previous single-month records and was 5.2°F (2.9°C) higher than the long-term climatological average.¹¹ Studies demonstrated a 3.6% increase in emergency room visits and a 0.6% increase in deaths, with the largest effect on the elderly.^142,143 Within the Southern Great Plains, changes in extreme temperatures are projected to result in an additional 1,300 deaths per year under a higher scenario (RCP8.5) by the end of the century. Under a lower scenario (RCP4.5), more than half of these additional deaths could be avoided. Annual losses associated with extreme temperature-related mortality are estimated at $19 billion (2015 dollars) under RCP8.5 in 2090 and $9.4 billion (2015 dollars) under RCP4.5¹⁴⁴ (see the Scenario Products section of App. 3 for more on RCPs).

Rising temperatures and precipitation alter the habitats of vectors (mosquitoes, ticks, rodents, and fleas) that transmit a variety of human diseases. In the Southern Great Plains, hantavirus,¹⁴⁵ Rocky Mountain spotted fever,¹⁴⁶ leptospirosis,¹⁴⁷ and West Nile virus¹⁴⁸ are all currently endemic and could be impacted by climate change.^149,150 A warmer world will create newly hospitable habitats for tropical and subtropical insect vectors and the diseases they carry. Historically disease-free areas have been protected from becoming hazardous by cold environmental temperatures. That is, with extreme low temperatures of winter, insect (in particular, mosquito) populations are decimated. However, as the global average temperature increases, mosquitoes will thrive longer and reproduce more successfully at higher latitudes and altitudes. Tropical diseases, such as dengue virus,¹⁵¹ chikungunya virus, and Zika virus are transmitted by Aedes mosquitoes, which are currently expanding their geographic range in the southern United States.¹⁴⁹ In southern Texas, sporadic, locally acquired outbreaks of dengue have been reported.¹⁵² In 2005, there were 59 cases of dengue virus in southern Texas that met criteria for dengue hemorrhagic fever,¹⁵³ indicating that inhabitants were exposed to multiple variations of the virus, a condition necessary for the development of severe manifestations of dengue. In 2014, locally transmitted cases of chikungunya began to be reported in Texas.¹⁵⁴ Zika virus has also recently appeared in the region. In 2016, the Centers for Disease Control and Prevention (CDC) issued a travel warning for Cameron County, Texas, after the first case of local, person-to-person transmission of Zika was reported.¹⁵⁵ The ecology of vector-borne diseases is complex, and the future risk for proliferation and expansion of the ranges of these diseases is possible under future climate scenarios.^156,157 Along the southern Gulf Coast, stronger hurricanes will increase the likelihood of favorable ecologic niches for emerging infectious diseases that infect humans and animals.¹⁵⁸

As water evaporates during periods of drought, the remaining water can have higher concentrations of chemicals and solid particles, lower dissolved oxygen levels, and a higher density of germs that cause infectious diseases.¹²⁸ Drought conditions reduce the number of sources and overall quantity of water available to both human and animal users. Because these users are sharing a reduced supply, germ transmission and outbreaks of infectious disease become more likely. Waterborne diseases that have been linked to drought include amoebiasis, hepatitis A, salmonellosis, schistosomiasis, shigellosis, typhoid and paratyphoid fevers, infection with E. coli, cholera, and leptospirosis.^{159,160,161,162} Skin infections, such as scabies and impetigo, and eye infections, including conjunctivitis, are also correlated with drought due to a lack of water available for personal hygiene.¹⁶³

Droughts, floods, and higher temperatures will change the balance of ecosystems, allowing invasive species such as animal pests, plant weeds, and algae blooms to proliferate and harm existing agriculture.¹⁶⁴ Such conditions favor fungal species that can overwhelm crops and contaminate animal feedstocks. Additionally, increases in CO₂ are changing the nutritional composition of food crops.¹⁶⁵ Elevated CO₂ levels have been shown to reduce the protein composition of grains, tubers, rice, wheat, and barley.¹⁶⁶ Micronutrient contents are also affected by rising CO₂ levels, with atmospheric CO₂ concentrations of 550 parts per million being associated with reductions in zinc, iron, phosphorus, potassium, calcium, sulfur, magnesium, copper, and manganese across a wide range of crops.¹⁶⁷ Additionally, extreme temperatures and aridity pose health risks to outdoor agricultural workers.¹⁶⁸ Under a higher scenario (RCP8.5), the impact of temperature extremes at a national level are projected to result in the loss of two billion labor hours, equating to an estimated $160 billion (in 2015 dollars) in lost wages by the end of the century. The Southern Great Plains region is projected to experience higher-than-average impacts, with some communities projected to lose more than 6% in annual labor hours by the end of the century.¹⁴⁴

State-level climate adaptation programs¹⁶⁹ have been developed throughout the Nation. For health, these include vulnerability and adaptation assessments, comprehensive response plans,^170,171 climate-proofing healthcare infrastructure, and implementing integrated surveillance of climate-sensitive infectious diseases. These efforts are outlined in more detail in Chapter 14: Human Health. Incorporating short-term to seasonal forecasts into public health activities can also provide assistance under a warming climate.¹⁷² Although there is momentum to adopt adaptation strategies in the wake of Hurricane Harvey,¹⁷³ and adaptation strategies on a general scale (such as for drought) are in progress,¹⁷⁴ large-scale adaptation efforts in the region are lacking¹⁷⁵ and regional planners can learn from activities ongoing outside the region (Ch. 14: Human Health).

The 45 federally recognized tribes (48 if state-recognized tribal nations are included) located in the Southern Great Plains show considerable economic, social, cultural, and linguistic/language diversity.^176,177,178 The 4 tribes of Kansas (59,130 people), 39 tribes of Oklahoma (482,760 people), including 1 state-recognized tribe, and 5 tribes of Texas (6,210 people), including 2 state-recognized tribes, experience the same climate change impacts as the rest of the Nation.¹⁴ However, these sovereign nations within the United States are faced with infrastructure (social and physical), economic, political, and cultural challenges, as well as unique opportunities, in their response to climate change impacts (Ch. 15: Tribes).

Climate Change Threats to Tribal Cultural Traditions and Community Resilience

No climate change impacts are as significant to the tribes and Indigenous peoples of the Southern Great Plains as those that threaten the ability to procure food, water, shelter, and preserve ancient cultural activities.^{179 180 181} Given the ancient symbiotic relationship between environment and culture that shapes tribal identities and life-way practices, climate-induced changes to the seasons, landscapes, and ecosystems pose an existential threat to tribal cultural traditions and community resilience.^182,183,184 For example, climate change, including the impacts of excessive heat, drought, and the disappearance of native species, is already disrupting ceremonial cycles in Oklahoma.¹⁸⁵ However, many climate change adaptation initiatives and strategies are being developed by tribes throughout the United States. Specific examples in the Southern Great Plains can be found in Figure 15.1 in Chapter 15: Tribes.

Physical and Organizational Infrastructure

The region’s tribes and Indigenous peoples vary greatly in size, from small nations with fewer than 1,000 enrolled members to larger nations with over 50,000 enrolled members; the largest of the tribes is the Cherokee Nation with more than 317,000 enrolled members.¹⁸⁶ The smaller nations, given their population size and respective size of government, often struggle to exercise their sovereignty to respond to climate change due to a lack of organizational and physical infrastructure.^187,188 The social organizational infrastructure needed to adapt to climate change impacts like extreme weather events, rising temperatures, shifting seasons, invasive species, air and water quality issues, and a host of health impacts is often lacking or underdeveloped in small tribal nations. Consequently, the smaller tribes depend largely on the services, grant programs, and technology transfer capabilities of the Bureau of Indian Affairs and other Federal Government departments, agencies, and bureaus to assist in their climate adaptation efforts. There are exceptions—larger and wealthier tribal nations, such as the Chickasaw Nation, Citizen Band Potawatomi, and Muscogee (Creek) Nation, can develop and shape, to a much larger extent, their own climate adaptation strategies.¹⁶⁹

Lack of physical infrastructure, tied directly to limited economic resources and power, poses a substantial obstacle to climate change adaptation for the tribes of the region. While cities and other governmental jurisdictions make plans to build resilient physical infrastructure by using bonds, public–private partnerships, and taxes and tax instruments, only a handful of tribal nations have the ability to use these tools for climate adaptation. Most tribes and Indigenous peoples remain dependent on underfunded federal programs and grants for building and construction activities to improve the resilience of their infrastructure in the face of climate change threats. Many larger and wealthier tribes have modeled construction and design of homes and large commercial building best practices on “green” or resilient net-zero carbon footprint designs. Increasing activity in community gardens, food recovery, recycling, water conservation, land-use planning, and investment in climate-resilient community design all signal opportunities for tribal nations to leapfrog significant obstacles other city, county, and state governments face when dealing with the costs of existing physical infrastructure that often make climate change adaptation difficult and incremental.