Fourth National Climate Assessment, Vol II | 12.12.2018

Recently, 13 USFederal agencies released the Fourth National Climate Assessment (NCA4), Volume II, Climate Change Impacts, Risks, and Adaptation in the United States. The National Climate Assessment is the most comprehensive, authoritative assessment of the effects of climate change on the US economy and communities. Included in the NCA4 is an assessment of climate variability and change and its impacts across the South Central United States. Notably, the states comprising the SCIPP region are represented in both Chapter 19: Southeast (Arkansas, Louisiana and coastal Mississippi) and Chapter 23: Southern Great Plains (Oklahoma and Texas).

Threatened infrastructure, altering ecosystems and species distributions, increased heath threats, urban and rural industry impacts, and sea level rise are among the major concerns and challenges detailed in the Southeast and Southern Great Plain chapters. In economic terms, the impacts add up to billions of dollars. The assessment finds that early action to address these impacts can lower economic, environmental, social, and cultural costs and could help to prevent conflict or displacement from lands and resources.

Both chapters lay out the changes already being felt in the South Central United States, as well as what lies ahead. The top findings for each region are included below.

The top findings for the Southeast include:

  • Expanding urbanization is creating new climate vulnerabilities for cities, especially on infrastructure and health. Poor air quality due to pollutants, wildfires and allergens, as well as heat-related illnesses are expected to increase with longer summer heat waves. Cities will also experience a greater risk to vector-borne diseases as favorable conditions for transmission will expand to year-round. More frequent heavy rainfall and flooding events are weakening the region’s roads and transit, and by 2050 the Southeast is expected to have the most vulnerable bridges in the nation.
  • Sea level rise has increased flooding in coastal and low-lying regions. Rising temperatures and changing ocean currents have contributed to increases in local relative sea levels at a rate higher than the global average and is resulting in greater high tide flooding frequencies and inland-moving storm surge. As sea levels continue to rise, flooding from these events are expected to increase in both frequency and duration and will further impact regions within flood prone areas such as on road closures, storm water management systems, and deterioration of infrastructure due to saltwater.
  • Ecosystems are threatened by a changing climate and will be transformed from shifting winter temperature extremes, wildfire patterns, rising sea levels, hurricanes, floods, droughts, and warming ocean temperatures. By 2100, a lengthening freeze-free season and less frequent and intense cold temperatures will lead to the northward migration and redistribution of tropical and subtropical species and organisms including insects, birds and plants. In addition, increased wildfire risks and invasive species will negatively impact the agriculture and forest industries.
  • Rural communities will experience greater health and economic vulnerabilities from increasing heat extremes and changing seasons. Agriculture, timber and manufacturing sectors are imperial across the Southeast and are at risk of decreasing productivity and losing over one-half billion labor hours to extreme heat-related impacts by 2100. More than half of the land across the Southeast remains rural and will experience greater health risks and stresses on cooling demands, especially on poverty-stricken areas.

The top findings for the Southern Great Plains include:

  • Demands for food, energy and water resources will increase with growing populations, urban economic development opportunities and increasing drought periods. Recent severe droughts exposed challenges at the intersection of these three resources, negatively impacting agriculture production, water consumption and treatment, and energy production. Increasing hydrological extremes along with a projected 20% increase in water demand by mid-century due to population growth will continue to deepen these impacts across the Southern Great Plains.
  • Habitats of species are being altered by a changing climate. Rising temperatures and the shift to a drier climate have led to the northward migration of species such as birds and butterflies and threatens the decline of certain species including the lesser prairie-chicken. Higher water temperatures and lower salinity levels have led to an increase in harmful algae blooms and threatens sensitive estuarian species.
  • Infrastructure is becoming increasingly vulnerable to rising temperatures, extreme precipitation and continued sea level rise. Longer, hotter summers will create more stress on cooling systems, energy utilities and road surfaces. Increases in both heavy rain and drought periods will further threaten roads, aging pipelines, sewer lines, building foundations, and several dams and levees. The coastal region of Texas is especially vulnerable to rising sea levels, experiencing higher than normal rates due to the extraction of fossil fuels and groundwater. By 2050, an expected $30 billion in property values will be exposed to rising sea levels and more frequent flooding.
  • These changes will negatively impact human health, including through heat related illnesses and deaths, and diseases transmitted through food, water and insects.
  • Climate-induced changes pose an existential threat to Indigenous peoples, including to tribal cultural traditions and community resilience. Excessive heat, drought and the changing of native species are disrupting ceremonial cycles and increasing health threats. Efforts to build community resilience can be hindered by economic, political and infrastructure limitations, but opportunities exist to implement adaptation practices otherwise limited to city and state governments.

In the face of such risks, groups across the region are working together to identify opportunities for adaptation and to lessen impacts from a changing climate. Current regional adaptation actions across the SCIPP region include integrating climate services and early warning systems to improve the development of sustainable infrastructure and increase agricultural production. Other examples of adaptation measures include installing cool roofs to lessen heat impacts, improving planning and monitoring prior to flood events, strengthening or relocating critical infrastructure, participating in the Federal Emergency Management Agency’s Community Rating System program, practicing prescribed fire to reduce wildfire impacts, and implementing drought contingency plans and water-use cutbacks. As the science is becoming more evident, adaptation strategies will continue to increase the opportunities for policymakers, practitioners and scientists across the SCIPP region to increase resiliency and lessen impacts in a changing climate.

About the Fourth National Climate Assessment

Mandated in the Global Change Research Act passed by Congress in 1990, the National Climate Assessment synthesizes the state of climate knowledge and assesses climate change impacts, risks, and adaptation across the United States
every four years. The main objective is to help Americans better identify, avoid, and/or reduce climate-related risks. The National Climate Assessment process relies on consensus and undergoes extensive review.

Volume II of the Fourth National Climate Assessment builds upon the physical science assessment presented in Volume I, the Climate Science Special Report, released in November 2017. Vol. II places a strong emphasis on regional information, addressing the impacts of climate change on 10 regions of the United States. It also evaluates the risks from climate changes across 15 national-level topics, often using case studies to provide additional context and showcase community success stories.

The report was written by more than 300 Federal and non-Federal authors representing a range of expertise, a number of whom were selected through a public call for nominations. The Southeast chapter has nine authors, the lead
author of which was former LSU SCIPP program manager Dr. Lynne Carter, and five technical contributors including LSU SCIPP’s Vincent Brown and Dr. Barry Keim. The Southern Great Plains chapter has 15 authors including OU SCIPP’s Dr. Mark Shafer, and one technical contributor. Both chapters are backed by more than 190 citations from published articles, reports, and books.