 Section 15 of the Fourth National Climates Assessment. Volume 2 by USG-CRP. This LibriVox recording is in the public domain. Recording by Warren Coddy, Gurney, Illinois. CHAPTER XIII. AIR QUALITY KEY MESSAGE 1. INCREASING RISKS FROM AIR PROLUTION More than 100 million people in the United States live in communities where air pollution exceeds health-based air quality standards. Unless counteracting efforts to improve air quality are implemented, climate change will worsen existing air pollution levels. This worsened air pollution would increase the incidence of adverse respiratory and cardiovascular health effects, including premature death. Increased air pollution would also have other environmental consequences, including reduced visibility and damage to agricultural crops and forests. KEY MESSAGE 2. INCREASING IMPACTS OF WILD FIERS Wildfire smoke degrades air quality, increasing the health risks to tens of millions of people in the United States. More frequent and severe wildfires, due to climate change, would further diminish air quality, increase incidences of respiratory illness from exposure to wildfire smoke, impair visibility, and disrupt outdoor recreational activities. KEY MESSAGE 3. INCREASES IN AIR BORN ALLERGY EXPOSURE The frequency and severity of allergic illnesses, including asthma and hay fever, are likely to increase as a result of a changing climate. Earlier spring arrival, warmer temperatures, changes in precipitation, and higher carbon dioxide concentrations, can increase exposure to airborne pollen allergens. KEY MESSAGE 4. COE BENEFITS OF GREENHOUSE GAS MIDIGATION Many emission sources of greenhouse gases also emit air pollutants that harm human health. Controlling these common emission sources would both mitigate climate change and have immediate benefits for air quality and human health. Because methane is both a greenhouse gas and an ozone precursor, reductions of methane emissions have the potential to simultaneously mitigate climate change and improve air quality. Unless offset by additional emissions reductions of ozone precursor emissions, there is high confidence that climate change will increase ozone levels over most of the United States, particularly over already polluted areas, thereby worsening the detrimental health and environmental effects due to ozone. The climate penalty results from changes in local weather conditions, including temperature and atmospheric circulation patterns, as well as changes in ozone precursor emissions that are influenced by meteorology. Climate change has already had an influence on ozone concentrations over the United States, offsetting some of the expected ozone benefit from reduced precursor emissions. The magnitude of the climate penalty over the United States could be reduced by mitigating climate change. Climate changes, including warmer springs, longer summer dry seasons, and drier soils and vegetation have already lengthened the wildfire season and increased the frequency of large wildfires. Exposure to wildfire smoke increases the risk of respiratory disease, resulting in adverse impacts to human health. Longer fire seasons and increases in the number of large fires would impair both human health and visibility. Climate change, specifically rising temperatures and increased carbon dioxide, CO2 concentrations, can influence plant-based allergens, hay fever, and asthma in three ways. By increasing the duration of the pollen season, by increasing the amount of pollen produced by plants, and by altering the degree of allergic reactions to the pollen. The energy sector, which includes energy production, conversion, and use, accounts for 84% of greenhouse gas, GHG, emissions in the United States, as well as 80% of emissions of nitrogen oxides, NOx, and 96% of sulfur dioxide, the major precursor of sulfate aerosol. In addition to reducing future warming, reductions in GHG emissions often result in co-benefits, other positive effects such as improved air quality, and possibly some negative effects, disc benefits, chapter 29 mitigation. Specifically, mitigating GHG emissions can lower emissions of particulate matter, PM, ozone, and PM precursors, and other hazardous pollutants, reducing the risks to human health from air pollution. For full chapter, including references and traceable accounts, see HTTPS colon double backslash nca2018.globalchange.gov backslash chapter backslash air-quality. End of section 15. Section 16 of the Fourth National Climate Assessment, Volume 2 by USG-CRP. This LibriVox recording is in the public domain. Recording by Warren Coddy, Gurney, Illinois. Chapter 14 Human Health. Key Message 1. Climate change affects the health of all Americans. The health and well-being of Americans are already affected by climate change, with the adverse health consequences projected to worsen with additional climate change. Climate change affects human health by altering exposures to heat waves, floods, droughts, and other extreme events, vector food and waterborne infectious diseases, changes in the quality and safety of air, food, and water, and stresses to mental health and well-being. Key Message 2. Exposure and resilience vary across populations and communities. People and communities are differentially exposed to hazards and disproportionately affected by climate-related health risks. Populations experiencing greater health risks include children, older adults, low-income communities, and some communities of color. Key Message 3. Adaptation reduces risks and improves health. Proactive adaptation policies and programs reduce the risks and impacts from climate-sensitive health outcomes and from disruptions in health care services. Additional benefits to health arise from explicitly accounting for climate change risks in infrastructure planning and urban design. Key Message 4. Reducing greenhouse gas emissions results in health and economic benefits. Reducing greenhouse gas emissions would benefit the health of Americans in the near and long term. By the end of this century, thousands of American lives could be saved and hundreds of billions of dollars in health-related economic benefits gained each year under a pathway of lower greenhouse gas emissions. Key Message 5. Climate-related changes in weather patterns and associated changes in air, water, food, and the environment are affecting the health and well-being of the American people, causing injuries, illnesses, and death. Increasing temperatures increases in the frequency and intensity of heat waves since the 1960s, changes in precipitation patterns, especially increases in heavy precipitation, and sea level rise can affect our health through multiple pathways. Changes in weather and climate can degrade air and water quality affect the geographic range, seasonality, and intensity of transmission of infectious diseases through food, water, and disease-carrying vectors such as mosquitoes and ticks, and increase stresses that affect mental health and well-being. Changing weather patterns also interact with demographic and socioeconomic factors as well as underlying health trends to influence the extent of the consequences of climate change for individuals and communities. While all Americans are at risk of experiencing adverse climate-related health outcomes, some populations are disproportionately vulnerable. The risks of climate change for human health are expected to increase in the future, with the extent of the resulting impacts dependent on the effectiveness of adaptation efforts and on the magnitude and pattern of future climate change. Individuals, communities, public health departments, health-related organizations and facilities, and others, are taking action to reduce health vulnerability to current climate change and to increase resilience to the risks projected in coming decades. The health benefits of reducing greenhouse gas emissions could result in economic benefits of hundreds of billions of dollars each year by the end of the century. Annual health impacts and health-related costs are projected to be approximately 50% lower under a lower scenario, RCP 4.5, compared to a higher scenario, RCP 8.5. These estimates would be even larger if they included the benefits of health outcomes that are difficult to quantify, such as avoided mental health impacts or long-term physical health impacts. For full chapter, including references and traceable accounts, see end of section 16. Section 17 of the Fourth National Climate Assessment, volume 2 by USG-CRP. This Slibervox recording is in the public domain. Recording by Warren Coddy, Gurnee, Illinois. Chapter 15. Tribes and Indigenous Peoples. Key Message 1. Indigenous Livelihoods and Economies at Risk. Climate change threatens Indigenous Peoples' livelihoods and economies, including agriculture, hunting and gathering, fishing, forestry, energy, recreation and tourism enterprises. Indigenous Peoples' economies rely on, but face institutional barriers to, their self-determined management of water, land, other natural resources, and infrastructure that will be impacted increasingly by changes in climate. Key Message 2. Physical, mental, and Indigenous values-based health at risk. Indigenous health is based on interconnected social and ecological systems that are being disrupted by a changing climate. As these changes continue, the health of individuals and communities will be uniquely challenged by climate impacts to lands, waters, foods, and other plant and animal species. These impacts threaten sites, practices, and relationships with cultural, spiritual, or ceremonial importance that are foundational to Indigenous Peoples' cultural heritages, identities, and physical and mental health. Key Message 3. Adaptation, disaster management, displacement, and community-led relocations. Many Indigenous Peoples have been proactively identifying and addressing climate impacts. However, institutional barriers exist in the United States that severely limit their adaptive capacities. These barriers include limited access to traditional territory and resources, and the limitations of existing policies, programs, and funding mechanisms in accounting for the unique conditions of Indigenous communities. Successful adaptation in Indigenous contexts relies on use of Indigenous knowledge, resilient and robust social systems and protocols, a commitment to principles of self-determination, and proactive efforts on the part of federal, state, and local governments to alleviate institutional barriers. Indigenous Peoples in the United States are diverse and distinct political and cultural groups and populations. Though they may be affected by climate change in ways that are similar to others in the United States, Indigenous Peoples can also be affected uniquely and disproportionately. Many Indigenous Peoples have lived in particular areas for hundreds if not thousands of years. Indigenous Peoples' histories and shared experience and gender-distinct knowledge about climate change impacts and strategies for adaptation. Indigenous Peoples' traditional knowledge systems can play a role in advancing understanding of climate change and in developing more comprehensive climate adaptation strategies. Observed and projected changes of increased wildfire, diminished snowpack, pervasive drought, flooding, ocean acidification, and sea level rise threaten the viability of Indigenous Peoples' traditional subsistence and commercial activities that include agriculture, hunting and gathering, fisheries, forestry, energy, recreation, and tourism enterprises. Despite institutional barriers to tribal self-determination stemming from federal trust authority over tribal trust lands, a number of tribes have adaptation plans that include a focus on subsistence and commercial economic activities. Some tribes are also pursuing climate mitigation actions through the development of renewable energy on tribal lands. Climate impacts to lands, waters, foods, and other plant and animal species threaten cultural heritage sites and practices that sustain intra and intergenerational relationships built on sharing traditional knowledges, food, and ceremonial or cultural objects. This weakens place-based cultural identities, may worsen historical trauma still experienced by many Indigenous Peoples in the United States, and adversely affects mental health and Indigenous values-based understandings of health. Throughout the United States, climate-related disasters are causing Indigenous communities to consider or actively pursue relocation as an adaptation strategy. Challenges to Indigenous actions to address disaster management and recovery, displacement, and relocation in the face of climate change include economic, social, political, and legal considerations that severely constrain their abilities to respond to rapid ecological shifts and complicate action towards safe and self-determined futures for these communities. For full chapter, including references and traceable accounts, see HTTPS colon double backslash nca2018.globalchange.gov backslash chapter backslash tribes. End of section 17. Section 18 of the Fourth National Climate Assessment, Volume 2 by USG-CRP. This LibriVox recording is in the public domain. Recording by Warren Coddy, Gurney, Illinois. Chapter 16. Climate Defects on U.S. International Interests. Key Message 1. Economics and Trade. The impacts of climate change, variability, and extreme events outside the United States are affecting and are virtually certain to increasingly affect U.S. trade and economy, including import and export prices and businesses with overseas operations and supply chains. Key Message 2. International Development and Humanitarian Assistance. The impacts of climate change, variability, and extreme events can slow or reverse social and economic progress in developing countries, thus undermining international aid and investments made by the United States and increasing the need for humanitarian assistance and disaster relief. The United States provides technical and financial support to help developing countries better anticipate and address the impacts of climate change, variability, and extreme events. Key Message 3. Climate and National Security. Climate change, variability, and extreme events in conjunction with other factors can exacerbate conflict, which has implications for U.S. national security. Climate impacts already affect U.S. military infrastructure and the U.S. military is incorporating climate risks in its planning. Key Message 4. Transboundary Resources. Shared resources along U.S. land and maritime borders provide direct benefits to Americans and are vulnerable to impacts from a changing climate, variability, and extremes. Multinational frameworks that manage shared resources are increasingly incorporating climate risk in their transboundary decision-making processes. Key Message 5. U.S. international interests such as economics and trade, international development and humanitarian assistance, national security, and transboundary resources are affected by impacts from climate change, variability, and extreme events. Long-term changes in climate could lead to large-scale shifts in the global availability and prices of a wide array of agricultural, energy, and other goods with corresponding impacts on the U.S. economy. Some U.S.-led businesses are already working to reduce their exposure to risks posed by a changing climate. U.S. investments in international development are sensitive to climate-related impacts and will likely be undermined by more frequent and intense extreme events such as droughts, floods, and tropical cyclones. These events can impede development efforts and result in greater demand for U.S. humanitarian assistance and disaster relief. In response, the U.S. government has funded adaptation programs that seek to reduce vulnerability to climate impacts in critical sectors. Climate change, variability, and extreme events increase risks to national security through direct impacts on U.S. military infrastructure and, more broadly, through the relationship between climate-related stress on societies and conflict. Direct linkages between climate and conflict are unclear, but climate variability has been shown to affect conflict through intermediate processes, including resource competition, commodity price shocks, and food insecurity. The U.S. military is working to fully understand these threats and to incorporate projected climate changes into long-term planning. The impacts of changing weather and climate patterns across U.S. international borders affect those living in the United States. The changes pose new challenges for the management of shared and transboundary resources. Many bilateral agreements and public-private partnerships are incorporating climate risk and adaptation management into their near and long-term strategies. U.S. cooperation with international and other national scientific organizations improves access to global information and strategic partnerships, which better positions the nation to observe, understand, assess, and respond to the impacts associated with climate change, variability, and extremes on national interests both within and outside of U.S. borders. For full chapter, including references and traceable accounts, see HTTPS colon double backslash nca2018.globalchange.gov backslash chapter backslash international dash interests. End of section 18. Section 19 of the Fourth National Climate Assessment, Volume 2 by USG-CRP. This sleeper box recording is in the public domain. Recording by Warren Coddy, Gurney, Illinois. Chapter 17. Sector Interactions, Multiple Stressors, and Complex Systems. Key Message 1. Interactions Among Sectors 2. The sectors and systems exposed to climate, for example, energy, water, and agriculture, interact with and depend on one another and other systems less directly exposed to climate, such as the financial sector. In addition, these interacting systems are not only exposed to climate-related stressors, such as floods, droughts, and heat waves. They are also subject to a range of non-climate factors, from population movements to economic fluctuations to urban expansion. These interactions can lead to complex behaviors and outcomes that are difficult to predict. It is not possible to fully understand the implications of climate change on the United States without considering the interactions among sectors and their consequences. Key Message 2. Multi-Sector Risk Assessment Climate change risk assessment benefits from a multi-sector perspective encompassing interactions among sectors and both climate and non-climate stressors. Because such interactions and their consequences can be challenging to identify in advance, effectively assessing multi-sector risks requires tools and approaches that integrate diverse evidence and that consider a wide range of possible outcomes. Key Message 3. Management of Interacting Systems The joint management of interacting systems can enhance the resilience of communities, industries, and ecosystems to climate-related stressors. For example, during drought events, river operations can be managed to balance water demand for drinking water, navigation, and electricity production. Such integrated approaches can help avoid missed opportunities or unanticipated trade-offs associated with implementation of management responses to climate-related stressors. Key Message 4. Advancing Knowledge Predicting the responses of complex interdependent systems will depend on developing meaningful models of multiple diverse systems, including human systems, and methods for characterizing uncertainty. The world we live in is a web of natural, built, and social systems, from global and regional climate, to the electric grid, to water management systems such as dams, rivers, and canals, to managed and unmanaged forests, and to financial and economic systems. Climate affects many of these systems individually, but they also affect one another, and often in ways that are hard to predict. In addition, while climate-related risks such as heat waves, floods, and droughts have an important influence on these interconnected systems, these systems are also subject to a range of other factors, such as population growth, economic forces, technological change, and deteriorating infrastructure. A key factor in assessing risk in this context is that it is hard to quantify and predict all the ways in which climate-related stressors might lead to severe or widespread consequences for natural, built, and social systems. A multi-sector perspective can help identify such critical risks ahead of time, but uncertainties will always remain regarding exactly how consequences will materialize in the future. Therefore, effectively assessing multi-sector risks requires different tools and approaches than would be applied to understand a single sector by itself. In interacting systems, management responses within one system influence how other systems respond. Failure to anticipate interdependencies can lead to missed opportunities for managing the risks of climate change. It can also lead to management responses that increase risks to other parts of the system. Despite the challenge of managing system interactions, there are opportunities to learn from experience to guide future risk management decisions. There is a large gap in the multi-sector and multi-scale tools and frameworks that are available to describe how different human systems interact with one another and with the Earth system and how those interactions affect the total system response to the many stressors they are subject to, including climate-related stressors. Characterizing the nature of such interactions and building the capacity to model them are important research challenges. For full chapter including references and traceable accounts, see HTTPS colon double backslash nca2018.globalchange.gov backslash chapter backslash complex-systems. End of section 19. Section 20 of the Fourth National Climate Assessment, Volume 2 by USG-CRP. This LibriVox recording is in the public domain. Recording by Warren Coddy, Gurney, Illinois. Chapter 18, Northeast. T Message 1. Changing Seasons Effect Rural Ecosystems, Environments, and Economies. The seasonality of the northeast is central to the region's sense of place and is an important driver of rural economies. Less distinct seasons with milder winter and earlier spring conditions are already altering ecosystems and environments in ways that adversely impact tourism, farming, and forestry. The region's rural industries and livelihoods are at risk from further changes to forests, wildlife, snowpack, and stream flow. Key Message 2. Changing Coastal and Ocean Habitats, Ecosystem Services, and Livelyhoods. The northeast's coast and ocean support commerce, tourism, and recreation that are important to the region's economy and way of life. Warmer ocean temperatures, sea level rise, and ocean acidification threaten these services. The adaptive capacity of marine ecosystems and coastal communities will influence ecological and socio-economic outcomes as climate risks increase. G Message 3. Maintaining Urban Areas and Communities and Their Interconnectedness The northeast's urban centers and their interconnections are regional and national hubs for cultural and economic activity. Major negative impacts on critical infrastructure, urban economies, and nationally significant historic sites are already occurring and will become more common with a changing climate. Key Message 4. Threats to Human Health Changing climate threatens the health and well-being of people in the northeast through more extreme weather, warmer temperatures, degradation of air and water quality, and sea level rise. These environmental changes are expected to lead to health-related impacts and costs, including additional deaths, emergency room visits and hospitalizations, and a lower quality of life. Health impacts are expected to vary by location, age, current health, and other characteristics of individuals and communities. Key Message 5. Adaptation to Climate Change is Underway Communities in the northeast are proactively planning and implementing actions to reduce risks posed by climate change. Using decision support tools to develop and apply adaptation strategies informs both the value of adopting solutions and the remaining challenges. Experience, since the last assessment, provides a foundation to advance future adaptation efforts. The distinct seasonality of the northeast's climate supports a diverse natural landscape adapted to the extremes of cold, snowy winters and warm to hot, humid summers. This natural landscape provides the economic and cultural foundation for many rural communities, which are largely supported by a diverse range of agricultural, tourism, and natural resource-dependent industries. See Chapter 10, Ag and Rural, Key Message 4. The recent dominant trend in precipitation throughout the northeast has been towards increases in rainfall intensity, with increases in intensity exceeding those in other regions of the contiguous United States. Further increases in rainfall intensity are expected, with increases in total precipitation expected during the winter and spring, but with little change in the summer. Monthly precipitation in the northeast is projected to be about one inch greater for December through April by the end of century, 2070 through 2100, under the higher scenario, RCP 8.5. Ocean and coastal ecosystems are being affected by large changes in a variety of climate-related environmental conditions. These ecosystems support fishing and aquaculture, tourism and recreation, and coastal communities. Observed and projected increases in temperature, acidification, storm frequency and intensity, and sea levels are of particular concern for coastal and ocean ecosystems, as well as local communities and their interconnected social and economic systems. Increasing temperatures and changing seasonality on the northeast continental shelf have affected marine organisms and the ecosystem in various ways. The warming trend experienced in the northeast continental shelf has been associated with many fish and invertebrate species moving northward and to greater depths. Because of the diversity of the northeast's coastal landscape, the impacts from storms and sea level rise will vary at different locations along the coast. Northeastern cities, with their abundance of concrete and asphalt and a relative lack of vegetation, tend to have higher temperatures than surrounding regions due to the urban heat island effect. During extreme heat events, nighttime temperatures in the region's big cities are generally several degrees higher than surrounding regions, leading to higher risk of heat-related death. Urban areas are at risk for large numbers of evacuated and displaced populations and damaged infrastructure due to both extreme precipitation events and recurrent flooding, potentially requiring significant emergency response efforts and consideration of a long-term commitment to rebuilding and adaptation and or support for relocation where needed. Much of the infrastructure in the northeast, including drainage and sewer systems, flood and storm protection assets, transportation systems and power supply is nearing the end of its planned life expectancy. Climate-related disruptions will only exacerbate existing issues with aging infrastructure. Sea level rise has amplified storm impacts in the northeast, key message two, contributing to higher surges that extend farther inland, as demonstrated in New York City in the aftermath of Superstorm Sandy in 2012. Service and resource supply infrastructure in the northeast is at increasing risk of disruption, resulting in lower quality of life, economic declines and increased social inequality. Loss of public services affects the capacity of communities to function as administrative and economic centers and triggers disruptions of interconnected supply chains. Chapter 16, International, Key Message 1. Increases in annual average temperatures across the northeast range from less than one degree Fahrenheit, 0.6 degrees centigrade in West Virginia, to about three degrees Fahrenheit, 1.7 degrees centigrade or more in New England since 1901. Although the relative risk of death on very hot days is lower today than it was a few decades ago, heat-related illness and death remain significant public health problems in the northeast. For example, a study in New York City estimated that in 2013 there were 133 excess deaths due to extreme heat. These projected increases in temperature are expected to lead to substantially more premature deaths, hospital admissions and emergency department visits across the northeast. For example, in the northeast we can expect approximately 650 additional premature deaths per year from extreme heat by the year 2050 under either a lower RCP 4.5 or higher RCP 8.5 scenario and from 960 under RCP 4.5 to 2300 under RCP 8.5 more premature deaths per year by 2090. Communities, towns, cities, counties, states and tribes across the northeast are engaged in efforts to build resilience to environmental challenges and adapt to a changing climate. Developing and implementing climate adaptation strategies in daily practice often occur in collaboration with state and federal agencies. Advances in rural towns, cities and suburban areas include low-cost adjustments of existing building codes and standards. In coastal areas, partnerships among local communities and federal and state agencies leverage federal adaptation tools and decision support frameworks. Increasingly cities and towns across the northeast are developing or implementing plans for adaptation and resilience in the face of changing climate. The approaches are designed to maintain and enhance the everyday lives of residents and promote economic development. In some cities, adaptation planning has been used to respond to present and future challenges in the built environment. Regional efforts have recommended changes in design standards when building, replacing or retrofitting infrastructure to account for a changing climate. For full chapter including references and traceable accounts, see HTTPS colon double backslash nca2018.globalchange.gov backslash chapter backslash northeast end of section 20 section 21 of the fourth national climate assessment volume 2 by USGCRP. This LibriVox recording is in the public domain. Recording by Warren Coddy, Gurney, Illinois. Chapter 19, Southeast Key Message 1. Urban Infrastructure and Health Risks Many southeastern cities are particularly vulnerable to climate change compared to cities in other regions with expected impacts to infrastructure and human health. The vibrancy and viability of these metropolitan areas, including the people and critical regional resources located in them, are increasingly at risk due to heat, flooding, and vector-borne disease brought about by a changing climate. Many of these urban areas are rapidly growing and offer opportunities to adopt effective adaptation efforts to prevent future negative impacts of climate change. Key Message 2. Increasing Flood Risks in Coastal and Low Lying Regions The southeastern coastal plain and inland low-lying regions support a rapidly growing population, a tourism economy, critical industries, and important cultural resources that are highly vulnerable to climate change impacts. The combined effects of changing extreme rainfall events and sea level rise are already increasing flood frequencies, which impacts property values and infrastructure viability, particularly in coastal cities. Without significant adaptation measures, these regions are projected to experience daily high-tide flooding by the end of the century. Key Message 3. Natural Ecosystems Will Be Transformed The southeastern diverse natural systems, which provide many benefits to society, will be transformed by climate change. Changing winter temperature extremes, wildfire patterns, sea levels, hurricanes, floods, droughts, and warming ocean temperatures are expected to redistribute species and greatly modify ecosystems. As a result, the ecological resources that people depend on for livelihood, protection, and well-being are increasingly at risk, and future generations can expect to experience and interact with natural systems that are much different than those we see today. Key Message 4. Economic and Health Risks for Rural Communities Rural communities are integral to the Southeast's cultural heritage and to the strong agricultural and forest products industries across the region. More frequent extreme heat episodes and changing seasonal climates are projected to increase exposure-linked health impacts and economic vulnerabilities in the agricultural, timber, and manufacturing sectors. By the end of the century, over one-half billion labor hours could be lost from extreme heat-related impacts. Such changes would negatively impact the region's labor-intensive agricultural industry and compound existing social stresses in rural areas related to limited local community capabilities and associated with rural demography, occupations, earnings, literacy, and poverty incidents. Reduction of existing stresses can increase resilience. The Southeast includes vast expanses of coastal and inland low-lying areas, the southern portion of the Appalachian Mountains, numerous high-growth metropolitan areas, and large rural expanses. These beaches and bayouss, fields and forests, and cities in small towns are all at risk from a changing climate. While some climate change impacts, such as sea level rise and extreme downpours, are being acutely felt now, others, like increasing exposure to dangerous high temperatures, humidity, and new local diseases, are expected to become more significant in the coming decades. While all regional residents and communities are potentially at risk for some impacts, some communities or populations are at greater risk due to their locations, services available to them, and economic situations. Observed warming since the mid-20th century has been uneven in the Southeast region, with average daily minimum temperatures increasing three times faster than average daily maximum temperatures. The number of extreme rainfall events is increasing. Climate model simulations of future conditions project increases in both temperature and extreme precipitation. Trends toward a more urbanized and denser Southeast are expected to continue, creating new climate vulnerabilities. Cities across the Southeast are experiencing more and longer summer heat waves. Vector-borne diseases pose a greater risk in cities than in rural areas because of higher population densities and other human factors. And the major urban centers in the Southeast are already impacted by poor air quality during warmer months. Increasing precipitation and extreme weather events will likely impact roads, freight rail, and passenger rail, which will likely have cascading effects across the region. Infrastructure related to drinking water and wastewater treatment also has the potential to be compromised by climate-related events. Increases in extreme rainfall events and high tide coastal floods due to future climate change will impact the quality of life of permanent residents as well as tourists visiting the low-lying and coastal regions of the Southeast. Sea-level rise is contributing to increased coastal flooding in the Southeast and high tide flooding already poses daily risks to businesses, neighborhoods, infrastructure, transportation, and ecosystems in the region. There have been numerous instances of intense rainfall events that have had devastating impacts on inland communities in recent years. The ecological resources that people depend on for livelihoods, protection, and well-being are increasingly at risk from the impacts of climate change. Sea-level rise will result in the rapid conversion of coastal, terrestrial, and freshwater ecosystems to tidal saline habitats. Reductions in the frequency and intensity of cold winter temperature extremes are already allowing tropical and subtropical species to move northward and replace more temperate species. Warmer winter temperatures are also expected to facilitate the northward movement of problematic invasive species, which could transform natural systems north of their current distribution. In the future, rising temperatures and increases in the duration and intensity of drought are expected to increase wildfire currents and also reduce the effectiveness of prescribed fire practices. Many in rural communities are maintaining connections to traditional livelihoods and relying on natural resources that are inherently vulnerable to climate changes. Climate trends and possible climate futures show patterns that are already impacting and are projected to further impact rural sectors from agriculture and forestry to human health and labor productivity. Future temperature increases are projected to pose challenges to human health. Increases in temperatures, water stress, freeze free days, drought, and wildfire risks, together with changing conditions for invasive species and the movement of diseases, create a number of potential risks for existing agricultural systems. Rural communities tend to be more vulnerable to these changes due to factors such as demography, occupations, earnings, literacy, and poverty incidents. In fact, a recent economic study using a higher scenario, RCP 8.5, suggests that the southern and midwestern populations are likely to suffer the largest losses from future climate changes in the United States. Climate change tends to compound existing vulnerabilities and exacerbate existing inequities. Already poor regions, including those found in the southeast, are expected to continue incurring greater losses than elsewhere in the United States. For full chapter, including references and traceable accounts, see HTTPS colon double backslash nca2018.globalchange.gov backslash chapter backslash southeast end of section 21 section 22 of the fourth national climate assessment volume two by USG CRP. This LibriVox recording is in the public domain. Recording by Warren Coddy, Gurney, Illinois. Chapter 20 US Caribbean Key Message 1 Fresh Water Fresh water is critical to life throughout the Caribbean. Increasing global carbon emissions are projected to reduce average rainfall in this region by the end of the century, constraining freshwater availability, while extreme rainfall events, which can increase freshwater flooding impacts, are expected to increase in intensity. Saltwater intrusion associated with sea level rise will reduce the quantity and quality of fresh water in coastal aquifers. Increasing variability in rainfall events and increasing temperatures will likely alter the distribution of ecological life zones and exacerbate existing problems in water management, planning, and infrastructure capacity. Key Message 2 Marine Resources Marine ecological systems provide key ecosystem services such as commercial and recreational fisheries and coastal protection. These systems are threatened by changes in ocean surface temperature, ocean acidification, sea level rise, and changes in the frequency and intensity of storm events. Degredation of coral and other marine habitats can result in changes in the distribution of species that use these habitats and the loss of live coral cover, sponges, and other key species. These changes will likely disrupt valuable ecosystem services, producing subsequent effects on Caribbean island economies. Key Message 3 Coastal Systems Coasts are a central feature of Caribbean island communities. Coastal zones dominate island economies and are home to critical infrastructure, public and private property, cultural heritage, and natural ecological systems. Sea level rise, combined with stronger wave action and higher storm surges, will worsen coastal flooding and increase coastal erosion, likely leading to diminished beach area, loss of storm surge barriers, decreased tourism, and negative effects on livelihoods and well-being. Adaptive planning and nature-based strategies, combined with active community participation and traditional knowledge, are beginning to be deployed to reduce the risks of a changing climate. Key Message 4 Rising Temperatures Natural and social systems adapt to the temperatures under which they evolve and operate. Changes to average and extreme temperatures have direct and indirect effects on organisms and strong interactions with hydrological cycles, resulting in a variety of impacts. Continued increases in average temperatures will likely lead to decreases in agricultural productivity, changes in habitats and wildlife distributions, and risks to human health, especially in vulnerable populations. As maximum and minimum temperatures increase, there are likely to be fewer cool nights and more frequent hot days, which will likely affect the quality of life in the U.S. Caribbean. Key Message 5 Disaster Risk Response to Extreme Events Extreme events pose significant risks to life, property, and economy in the Caribbean, and some extreme events, such as flooding and droughts, are projected to increase in frequency and intensity. Increasing hurricane intensity and associated rainfall rates will likely affect human health and well-being, economic development, conservation, and agricultural productivity. Increased resilience will depend on collaboration and integrated planning, preparation, and responses across the region. Key Message 6 Increasing Adaptive Capacity Through Regional Collaboration Shared knowledge, collaborative research and monitoring, and sustainable institutional adaptive capacity can help support and speed up disaster recovery, reduce loss of life, enhance food security, and improve economic opportunity in the U.S. Caribbean. Increased regional cooperation and stronger partnerships in the Caribbean can expand the region's collective ability to achieve effective actions that build climate change resilience, reduce vulnerability to extreme events, and assist in recovery efforts. Key Message 7 Historically, the U.S. Caribbean region has experienced relatively stable seasonal rainfall patterns, moderate annual temperature fluctuations, and a variety of extreme weather events, such as tropical storms, hurricanes, and drought. However, the Caribbean climate is changing and is projected to be increasingly variable as levels of greenhouse gases in the atmosphere increase. The high percentage of coastal area relative to the total island land area in the U.S. Caribbean means that a large proportion of the region's people, infrastructure, and economic activity are vulnerable to sea level rise, more frequent intense rainfall events, and associated coastal flooding, and saltwater intrusion. High levels of exposure and sensitivity to risk in the U.S. Caribbean region are compounded by a low level of adaptive capacity due in part to the high costs of mitigation and adaptation measures relative to the region's gross domestic product, particularly when compared to the continental U.S. coastal areas. The limited geographic and economic scale of Caribbean islands means that disruptions from extreme climate-related events, such as droughts and hurricanes, can devastate large portions of local economies and cause widespread damage to crops, water supplies, infrastructure, and other critical resources and services. The U.S. Caribbean territories of Puerto Rico and the U.S. Virgin Islands, USVI, have distinct differences in topography, language, population size, governance, natural and human resources, and economic capacity. However, both are highly dependent on natural and built coastal assets. Service-related industries account for more than 60 percent of the USVI economy. Beaches, affected by sea level rise and erosion, are among the main tourist attractions. In Puerto Rico, critical infrastructure, for example drinking water pipelines and pump stations, sanitary pipelines and pump stations, wastewater treatment plants, and power plants, is vulnerable to the effects of sea level rise, storm surge, and flooding. In the USVI, infrastructure and historical buildings in the inundation zone for sea level rise include the power plants on both St. Thomas and St. Croix. Schools, housing communities, the towns of Charlotte Amali, Christiane Stead and Fredericks Stead, and pipelines for water and sewage. Climate change will likely result in water shortages due to an overall decrease in annual rainfall, a reduction in ecosystem services, and increased risks for agriculture, human health, wildlife, and socioeconomic development in the US Caribbean. These shortages would result from some locations within the Caribbean experiencing longer dry seasons and shorter but wetter wet seasons in the future. Extended dry seasons are projected to increase fire likelihood. Excessive rainfall, coupled with poor construction practices, unpaved roads, and steep slopes, can exacerbate erosion rates and have adverse effects on reservoir capacity, water quality, and near shore marine habitats. Ocean warming poses a significant threat to the survival of corals and will likely also cause shifts in associated habitats that compose the coral reef ecosystem. Severe, repeated, or prolonged periods of high temperatures leading to extended coral bleaching can result in colony death. Ocean acidification also is likely to diminish the structural integrity of coral habitats. Studies show that major shifts in fisheries distribution and changes to the structure and composition of marine habitats adversely affect food security, shoreline protection, and economies throughout the Caribbean. In Puerto Rico, the annual number of days with temperatures above 90 degrees Fahrenheit has increased over the last four and a half decades. During that period, stroke and cardiovascular disease, which are influenced by such elevated temperatures, became the primary causes of death. Increases in average temperature and in extreme heat events will likely have detrimental effects on agricultural operations throughout the US Caribbean region. Many farmers in the tropics, including the US Caribbean, are considered small holding, limited resource farmers, and often lack the resources and or capital to adapt to changing conditions. Most Caribbean countries and territories share the need to assess risks, enable actions across scales, and assess changes in ecosystems to informed decision making on habitat protection under a changing climate. US Caribbean islands have the potential to improve adaptation and mitigation actions by fostering stronger collaborations with Caribbean initiatives on climate change and disaster risk reduction. For full chapter, including references and traceable accounts, see HTTPS colon double backslash nca2018.globalchange.gov backslash chapter backslash Caribbean. End of section 22. Section 23 of the Fourth National Climate Assessment, volume two by USGCRP. This LibriVox recording is in the public domain. Recording by Warren Cotty, Gurney, Illinois. Chapter 21 Midwest Key Message 1. Agriculture. The Midwest is a major producer of a wide range of food and animal feed for national consumption and international trade. Increases in warm season, absolute humidity and precipitation have eroded soils, created favorable conditions for pests and pathogens, and degraded the quality of stored grain. Projected changes in precipitation, coupled with rising extreme temperatures before mid-century, will reduce Midwest agricultural productivity to levels of the 1980s without major technological advances. Key Message 2. Forestry. Midwest forests provide numerous economic and ecological benefits, yet threats from a changing climate are interacting with existing stressors, such as invasive species and pests, to increase tree mortality and reduce forest productivity. Without adaptive actions, these interactions will result in the loss of economically and culturally important tree species such as paper birch and black ash, and are expected to lead to the conversion of some forests to other forest types or even to non-forested ecosystems by the end of the century. Land managers are beginning to manage risk in forests by increasing diversity and selecting for tree species adapted to a range of projected conditions. Key Message 3. Biodiversity and Ecosystems. The ecosystems of the Midwest support a diverse array of native species and provide people with essential services, such as water purification, flood control, resource provision, crop pollination, and recreational opportunities. Species and ecosystems, including the important freshwater resources of the Great Lakes, are typically most at risk when climate stressors, like temperature increases, interact with land use change, habitat loss, pollution, nutrient inputs, and non-native invasive species. Restoration of natural systems increases in the use of green infrastructure and targeted conservation efforts, especially of wetland systems, can help protect people and nature from climate change impacts. Key Message 4. Human Health. Climate change is expected to worsen existing health conditions and introduce new health threats by increasing the frequency and intensity of poor air quality days, extreme high temperature events, and heavy rainfalls, extending pollen seasons, and modifying the distribution of disease-carrying pests and insects. By mid-century, the region is projected to experience substantial, yet avoidable, loss of life, worsened health conditions, and economic impacts estimated in the billions of dollars as a result of these changes. Improved basic health services and increased public health measures, including surveillance and monitoring, can prevent or reduce these impacts. Key Message 5. Transportation and Infrastructure. Stormwater management systems, transportation networks, and other critical infrastructure are already experiencing impacts from changing precipitation patterns and elevated flood risks. Green infrastructure is reducing some of the negative impacts by using plants and open space to absorb stormwater. The annual cost of adapting urban stormwater systems to more frequent and severe storms is projected to exceed $500 million for the Midwest by the end of the century. Key Message 6. Community vulnerability and adaptation. At-risk communities in the Midwest are becoming more vulnerable to climate change impacts, such as flooding, drought, and increases in urban heat islands. Tribal nations are especially vulnerable because of their reliance on threatened natural resources for their cultural, subsistence, and economic needs. Integrating climate adaptation into planning processes offers an opportunity to better manage climate risks now. Developing knowledge for decision-making in cooperation with vulnerable communities and tribal nations will help to build adaptive capacity and increase resilience. The Midwest is home to over 60 million people, and its active economy represents 18 percent of the U.S. gross domestic product. The region is probably best known for agricultural production. Increases in growing season temperature in the Midwest are projected to be the largest contributing factor to declines in the productivity of U.S. agriculture. Increases in humidity in spring through mid-century are expected to increase rainfall, which will increase the potential for soil erosion and further reduce planting season workdays due to waterlogged soil. Forests are a defining characteristic of many landscapes within the Midwest, covering more than 91 million acres. However, a changing climate, including an increased frequency of late growing season drought conditions, is worsening the effects of invasive species, insect pests, and plant diseases as trees experience periodic moisture stress. Impacts from human activities, such as logging, fire suppression, and agricultural expansion have lowered the diversity of the Midwest's forests from the pre-Euro-American settlement period. Natural resource managers are taking steps to address these issues by increasing the diversity of trees and introducing species suitable for a changing climate. The Great Lakes play a central role in the Midwest and provide an abundant freshwater resource for water supplies, industry, shipping, fishing, and recreation, as well as a rich and diverse ecosystem. These important ecosystems are under stress from pollution, nutrient and sediment inputs from agricultural systems, and invasive species. Lake surface temperatures are increasing, lake ice cover is declining, the seasonal stratification of temperatures in the lakes is occurring earlier in the year, and summer evaporation rates are increasing. Increasing storm impacts and declines in coastal water quality can put coastal communities at risk. While several coastal communities have expressed willingness to integrate climate action into planning efforts, access to useful climate information and limited human and financial resources constrain municipal action. Land conversion and a wide range of other stressors has already greatly reduced biodiversity in many of the region's prairies, wetlands, forests, and freshwater systems. Species are already responding to changes that have occurred over the last several decades and rapid climate change over the next century is expected to cause or further amplify stress in many species and ecological systems in the Midwest. The loss of species and the degradation of ecosystems have the potential to reduce or eliminate essential ecological services such as flood control, water purification, and crop pollination, thus reducing the potential for society to successfully adapt to ongoing changes. However, understanding these relationships also highlights important climate adaptation strategies. For example, restoring systems like wetlands and forested flood plains and implementing agricultural best management strategies that increase vegetative cover, cover crops and riparian buffers can help reduce flooding risks and protect water quality. Midwestern populations are already experiencing adverse health impacts from climate change and these impacts are expected to worsen in the future. In the absence of mitigation, ground level ozone concentrations are projected to increase across most of the Midwest, resulting in an additional 200 to 550 premature deaths in the region per year by 2050. Exposure to high temperatures impacts workers' health, safety, and productivity. Currently, days over 100 degrees Fahrenheit in Chicago are rare. However, they could become increasingly more common by late century in both the lower and higher scenarios, RCP 4.5 and RCP 8.5. The Midwest also has vibrant manufacturing, retail, recreation slash tourism, and service sectors. The region's highways, railroads, airports, and navigable rivers are major modes for commerce activity. Increasing precipitation, especially heavy rain events, has increased the overall flood risk, causing disruptions to transportation and damage to property and infrastructure. Increasing use of green infrastructure, including nature-based approaches such as wetland restoration and innovations like permeable pavements and better engineering practices are beginning to address these issues. Citizens and stakeholders value their health and the well-being of their communities, all of which are at risk from increased flooding, increased heat, and lower air and water quality under a changing climate. To better prevent and respond to these impacts, scholars and practitioners highlight the need to engage in risk-driven approaches that not only focus on assessing vulnerabilities, but also include effective planning and implementation of adaptation options. For full chapter, including references and traceable accounts, see HTTPS colon double backslash nca2018.globalchange.gov backslash chapter backslash midwest. End of section 23. Section 24 of the Fourth National Climate Assessment, Volume 2 by USGCRP. This LibriVox recording is in the public domain. Recording by Warren Caudy, Gurney, Illinois. Chapter 22. Northern Great Plains. Key Message 1. Water. Water is the lifeblood of the Northern Great Plains, and effective water management is critical to the region's people, crops, and livestock, ecosystems, and energy industry. Even small changes in annual precipitation can have large effects downstream. When coupled with the variability from extreme events, these changes make managing these resources a challenge. Future changes in precipitation patterns, warmer temperatures, and the potential for more extreme rainfall events are very likely to exacerbate these challenges. Key Message 2. Agriculture. Agriculture is an integral component of the economy, the history, and the culture of the Northern Great Plains. Recently, agriculture has benefited from longer growing seasons and other recent climatic changes. Some additional production and conservation benefits are expected in the next two to three decades as land managers employ innovative adaptation strategies, but rising temperatures and changes in extreme weather events are very likely to have negative impacts on parts of the region. Adaptation to extremes and to longer term persistent climate changes will likely require transformative changes in agricultural management, including regional shifts of agricultural practices and enterprises. Key Message 3. Recreation and Tourism. Ecosystems across the Northern Great Plains provide recreational opportunities and other valuable goods and services that are at risk in a changing climate. Rising temperatures have already resulted in shorter snow seasons, lower summer stream flows, and higher stream temperatures, and have negatively affected high elevation ecosystems and riparian areas, with important consequences for local economies that depend on winter or river-based recreational activities. Climate-induced land use changes in agriculture can have cascading effects on closely entwined natural ecosystems, such as wetlands, and the diverse species and recreational amenities they support. Federal, tribal, state, and private organizations are undertaking preparedness and adaptation activities such as scenario planning, transboundary collaboration, and development of market-based tools. Key Message 4. Energy. Fossil fuel and renewable energy production and distribution infrastructure is expanding within the Northern Great Plains. Climate change and extreme weather events put this infrastructure at risk, as well as the supply of energy it contributes to support individuals, communities, and the U.S. economy as a whole. The energy sector is also a significant source of greenhouse gases and volatile organic compounds that contribute to climate change and ground-level ozone pollution. Key Message 5. Indigenous Peoples. Indigenous Peoples of the Northern Great Plains are at high risk from a variety of climate change impacts, especially those resulting from hydrological changes, including changes in snowpack, seasonality and timing of precipitation events, and extreme flooding and droughts, as well as melting glaciers and reduction in stream flows. These changes are already resulting in harmful impacts to tribal economies, livelihoods, and sacred waters and plants used for ceremonies, medicine, and subsistence. At the same time, many tribes have been very proactive in adaptation and strategic climate change planning. In the Northern Great Plains, the timing and quantity of both precipitation and runoff have important consequences for water supplies, agricultural activities, and energy production. Overall, climate projections suggest that the number of heavy precipitation events, events with greater than one inch per day of rainfall, is projected to increase. Moving forward, the magnitude of year-to-year variability overshadows the small projected average decrease in stream flow. Changes in extreme events are likely to overwhelm average changes in both the eastern and western regions of the Northern Great Plains. Major flooding across the basin in 2011 was followed by severe drought in 2012, representing new and unprecedented variability that is likely to become more common in a warmer world. The Northern Great Plains region plays a critical role in national food security. Among other anticipated changes, projected warmer and generally wetter conditions with elevated atmospheric carbon dioxide concentrations are expected to increase the abundance and competitive ability of weeds and invasive species, increase livestock production and efficiency of production, and result in longer growing seasons at mid and high latitudes. Net primary productivity, including crop yields and forage production, is also likely to increase, although an increasing number of extreme temperature events during critical pollination and grain fill periods is likely to reduce crop yields. Ecosystems across the Northern Great Plains provide recreational opportunities and other valuable goods and services that are ingrained in the region's cultures. Higher temperatures, reduced snow cover, and more variable precipitation will make it increasingly challenging to manage the region's valuable wetlands, rivers, and snow-dependent ecosystems. In the mountains of western Wyoming and western Montana, the fraction of total water in precipitation that falls as snow is expected to decline by 25% to 40% by 2100 under a higher scenario, RCP 8.5, which would negatively affect the region's winter recreation industry. At lower elevation areas of the Northern Great Plains, climate-induced land use changes in agriculture can have cascading effects on closely entwined natural ecosystems, such as wetlands, and the diverse species and recreational opportunities they support. Energy resources in the Northern Great Plains include abundant crude oil, natural gas, coal, wind, and stored water, and, to a lesser extent, corn-based ethanol, solar energy, and uranium. The infrastructure associated with the extraction, distribution, and energy produced from these resources is vulnerable to the impacts of climate change. Railroads and pipelines are vulnerable to damage or disruption from increasing heavy precipitation events and associated flooding and erosion. Declining water availability in the summer would likely increase costs for oil production operations, which require fresh water resources. These cost increases will either lead to lower production or be passed on to consumers. Finally, higher maximum temperatures, longer and more severe heat waves, and higher overnight lows, are expected to increase electricity demand for cooling in the summer, further stressing the power grid. Indigenous peoples in the region are observing changes to climate, many of which are impacting livelihoods, as well as traditional subsistence and wild foods, wildlife, plants and water for ceremonies, medicines, and health and well-being. Because some tribes and Indigenous peoples are among those in the region with the highest rates of poverty and unemployment, and because many are still directly reliant on natural resources, they are among the most at risk to climate change. For a full chapter, including references and traceable accounts, see HTTPS colon double backslash nca2018.globalchange.gov backslash chapter backslash northern dash great dash planes. End of section 24. Section 25 of the Fourth National Climate Assessment, Volume 2 by USG-CRP. This sleeper box recording is in the public domain. Recording by Warren Cotty, Gurney, Illinois. Chapter 23 Southern Great Plains Key Message 1. Food, Energy, and Water Resources Quality of life in the region will be compromised as increasing population, the migration of individuals from rural to urban locations, and a changing climate, redistribute demand at the intersection of food consumption, energy production, and water resources. A growing number of adaptation strategies, improved climate services, and early warning decision support systems will more effectively manage the complex regional, national, and transnational issues associated with food, energy, and water. Key Message 2. Infrastructure 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. Key Message 3. Ecosystems and Ecosystem Services Terrestrial and aquatic ecosystems are being directly and indirectly altered by climate change. Some species can adapt to extreme droughts, unprecedented floods, and wildfires from a changing climate, while others cannot, resulting in significant impacts to both services and people living in these ecosystems. Landscape scale ecological services will increase the resilience of the most vulnerable species. Key Message 4. Human Health Health threats, including heat illness and diseases transmitted through food, water, and insects, will increase as temperature rises. Weather conditions supporting these health threats are projected to be of longer duration or occur at times of the year when these threats are not normally experienced. Extreme weather events, with resultant physical injury and population displacement, are also a threat. These threats are likely to increase in frequency and distribution, and are likely to create significant economic burdens. Vulnerability and adaptation assessments, comprehensive response plans, seasonal health forecasts, and early warning systems can be useful adaptation strategies. Key Message 5. Indigenous Peoples Tribal and Indigenous communities are particularly vulnerable to climate change due to water resource constraints, extreme weather events, higher temperature, and other likely public health issues. Efforts to build community resilience can be hindered by economic, political, and infrastructure limitations, but traditional knowledge and inter-tribal organizations provide opportunities to adapt to the potential challenges of climate change. The southern Great Plains experiences weather that is dramatic and consequential, from hurricanes and flooding to heat waves and drought. Its 34 million people, their infrastructure, and economies are often stressed, greatly impacting socioeconomic systems. The quality of life for the region's residents is dependent upon resources and natural systems for the sustainable provision of our basic needs, food, energy, and water. Extreme weather and climate events have redistributed demands for consumption, production, and supply across the region. Adaptation strategies that integrate climate services and early warning systems are improving our abilities to develop sustainable infrastructure and increase agricultural production, yet include the flexibility needed to embrace any changing demand patterns. Regional adaptation efforts that harden or relocate critical infrastructure will reduce the risk of climate change impacts. Redesigns of coastal infrastructure and the use of green slash gray methodologies are improving future coastal resilience. Energy industry reinvention is ensuring operations and reliability during extreme climatic events. Increasingly robust considerations of economic resilience allow us to anticipate risk, evaluate how that risk can affect our needs, and build a responsive adaptive capacity. With climate change, terrestrial and aquatic ecosystems and species within them have winners and losers. Those that can adapt are increases, while others cannot, resulting in impacts to traditional services and the livelihoods of the people who depend on those resources. The warming of coastal bay waters has been documented since at least the 1980s, and those increases in water temperature directly affect water quality, leading to hypoxia, harmful algal blooms, and fish kills, thus lowering their productivity and diversity of estuaries. Natural wetlands like the Playa Lakes and the High Plains, which have served for centuries as important habitat for migrating waterfowl, are virtually non-existent during drought. Direct human health threats follow a similar pattern of species within our natural ecosystems. Extreme weather results in both direct and indirect impacts to people, physical injury and population displacement are anticipated to result with climate change. Heat illness and diseases transmitted through food, water, and insects increase human risk as temperature rises. Acute awareness of these future impacts allows us to plan for the most vulnerable and adapt through response plans, health forecasting, and early warning strategies, including those that span transboundary contexts and systems. The impacts of climate change in general become more acute when considering tribal and indigenous communities. Resilience to climate change will be hindered by economic, political, and infrastructure limitations for these groups. At the same time, connectivity of the tribes and indigenous communities offers opportunities for teaching adaptably through their cultural means of applying traditional knowledge and inter-tribal organization. These well-honed connections of adapting through the centuries may help all of us learn how to offset the impacts and potential challenges of climate change. The role of climate change in altering the frequency of the types of severe weather most typically associated with the southern Great Plains, such as severe local storms, hail storms, and tornadoes remains difficult to quantify. Indirect approaches suggest a possible increase in the circumstances conducive to such severe weather, including an increase in the instances of larger hail sizes in the region by 2040. But changes are unlikely to be uniform across the region and additional research is needed. For a full chapter including references and traceable accounts, see HTTPS colon double backslash nca2018.globalchange.gov backslash chapter backslash southern-great-plains. End of section 25. Section 26 of the Fourth National Climate Assessment. Volume 2 by USG-CRP. This LibriVox recording is in the public domain. Recording by Warren Coddy, Gurney, Illinois. Chapter 24, Northwest. Key Message 1. Natural Resource Economy. Climate change is already affecting the Northwest's diverse natural resources, which support sustainable livelihoods, provide a robust foundation for rural, tribal, and indigenous communities, and strengthen local economies. Climate change is expected to continue affecting the natural resource sector, but the economic consequences will depend on future market dynamics, management actions, and adaptation efforts. Proactive management can increase the resilience of many natural resources and their associated economies. Key Message 2. Natural World and Cultural Heritage. Climate change and extreme events are already endangering the well-being of a wide range of wildlife, fish, and plants, which are intimately tied to tribal subsistence culture and popular outdoor recreation activities. Climate change is projected to continue to have adverse impacts on the regional environment with implications for the values, identity, heritage, cultures, and quality of life of the region's diverse population. Adaptation and informed management, especially culturally appropriate strategies, will likely increase the resilience of the region's natural capital. Key Message 3. Infrastructure. Existing water, transportation, and energy infrastructure already face challenges from flooding, landslides, drought, wildfire, and heat waves. Climate change is projected to increase the risks from many of these extreme events, potentially compromising the reliability of water supplies, hydropower, and transportation across the region. Isolated communities and those with systems that lack redundancy are the most vulnerable. Adaptation strategies that address more than one sector or are coupled with social and environmental co-benefits can increase resilience. Key Message 4. Health. Organizations and volunteers that make up the Northwest's social safety net are already stretched thin with current demands. Healthcare and social systems will likely be further challenged with the increasing frequency of acute events or when cascading events occur. In addition to an increased likelihood of hazards and epidemics, disruptions in local economies and food systems are projected to result in more chronic health risks. The potential health co-benefits of future climate mitigation investments could help to counterbalance these risks. Key Message 5. Front Line Communities Communities on the front lines of climate change experience the first, and often the worst, effects. Front line communities in the Northwest include tribes and indigenous peoples, those most dependent on natural resources for their livelihoods, and the economically disadvantaged. These communities generally prioritize basic needs such as shelter, food, and transportation, frequently lack economic and political capital, and have fewer resources to prepare for and cope with climate disruptions. The social and cultural cohesion inherent in many of these communities provides a foundation for building community capacity and increasing resilience. Residents of the Northwest list the inherent qualities of the natural environment among the top reasons to live in the region. The region is known for clean air, abundant water, low-cost hydroelectric power, vast forests, extensive farmlands, and outdoor recreation that includes hiking, boating, fishing, hunting, and skiing. Climate change, including gradual changes to the climate and in extreme climatic events, is already affecting these valued aspects of the region, including the natural resource sector, cultural identity, and quality of life, built infrastructure systems, and the health of Northwest residents. The communities on the front lines of climate change, tribes and indigenous peoples, those most dependent on natural resources for their livelihoods, and the economically disadvantaged, are experiencing the first, and often the worst, effects. In the third national climate assessment, the key messages for the Northwest focused on projected climate impacts to the region. These impacts, many of which are now better understood in the scientific literature, remain the primary climate concerns over the coming decades. In this updated assessment, the key messages explore how climate change could affect the interrelationships between the environment and the people of the Northwest. The extreme weather events of 2015 provide an excellent opportunity to explore projected changes in baseline climate conditions for the Northwest. The vast array of climate impacts that occurred over this record-breaking warm and dry year, coupled with the impacts of a multi-year drought, provide an enlightening glimpse into what may be more commonplace under a warmer, future climate. Record-low snowpack led to water scarcity and large wildfires that negatively affected farmers, hydropower, drinking water, air quality, salmon, and recreation. Warmer than normal ocean temperatures led to shifts in the marine ecosystem, challenges for salmon, and a large, harmful algal bloom that adversely affected the region's fisheries and shellfish harvests. Strong climate variability is likely to persist for the Northwest, owing in part to the year-to-year and decade-to-decade climate variability associated with the Pacific Ocean. Periods of prolonged drought are projected to be interspersed with years featuring heavy rainfall driven by powerful atmospheric rivers and strong El Nino winters associated with storm surge, large waves, and coastal erosion. Continued changes in the ocean environment, such as warmer waters, altered chemistry, sea level rise, and shifts in the marine ecosystems, are also expected. These changes would affect the Northwest's natural resource economy, cultural heritage, built infrastructure, and recreation, as well as the health and welfare of Northwest residents. The Northwest has an abundance of examples and case studies that highlight climate adaptation in progress and in practice, including creating resilient agro ecosystems that reduce climate-related risks, while meeting economic conservation and adaptation goals. Using green or hybrid green and gray infrastructure solutions that combine nature-based solutions with more traditional engineering approaches, and building social cohesion and strengthening social networks in front-line communities to assist in meeting basic needs while also increasing resilience to future climate stressors. Many of the case studies in this chapter demonstrate the importance of co-producing adaptation efforts with scientists, resource managers, communities, and decision makers as the region prepares for climate change impacts across multiple sectors and resources. For a full chapter including references and traceable accounts, see HTTPS colon double backslash nca2018.globalchange.gov backslash chapter backslash northwest end of section 26.