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.
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.
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.
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.
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.
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.
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.
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.
Virtually Certain | Extremely Likely | Very Likely | Likely | About as Likely as Not | Unlikely | Very Unikely | Extremely Unlikely | Exceptionally Unlikely |
---|---|---|---|---|---|---|---|---|
99%–100% | 95%–100% | 90%–100% | 66%-100% | 33%-66% | 0%-33% | 0%-10% | 0%-5% | 0%-1% |
Very High | Hoch | Medium | Niedrig |
---|---|---|---|
Strong evidence (established theory, multiple sources, consistent results, well documented and accepted methods, etc.), high consensus | Moderate evidence (several sources, some consistency, methods vary and/or documentation limited, etc.), medium consensus | Suggestive evidence (a few sources, limited consistency, models incomplete, methods emerging, etc.), competing schools of thought | Inconclusive evidence (limited sources, extrapolations, inconsistent findings, poor documentation and/or methods not tested, etc.), disagreement or lack of opinions among experts |
Documenting Uncertainty: This assessment relies on two metrics to communicate the degree of certainty in Key Findings. See Guide to this Report for more on assessments of likelihood and confidence.
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 adaptive 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.
<b>Smith</b>, J.B., M. Muth, A. Alpert, J.L. Buizer, J. Cook, A. Dave, J. Furlow, K. Preston, P. Schultz, and L. Vaughan, 2018: Climate Effects on U.S. International Interests. In <i>Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II</i> [Reidmiller, D.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, K.L.M. Lewis, T.K. Maycock, and B.C. Stewart (eds.)]. U.S. Global Change Research Program, Washington, DC, USA, pp. 604–637. doi: 10.7930/NCA4.2018.CH16
The global impacts of climate (climate change, variability, and extreme events) are already having important implications for societies and ecosystems around the world and are projected to continue to do so into the future.1,2,3 There are specific U.S. interests that can be affected by climate-related impacts outside of U.S. borders, such as climate variability (for example, El Niño/La Niña events), climate extremes (for example, floods resulting from extreme precipitation), and long-term changes (for example, sea level rise). These interests include economics and trade (Key Message 1), international development and humanitarian assistance (Key Message 2), national security (Key Message 3), and transboundary resources (Key Message 4). While these four topics are addressed separately, they can also affect each other. For example, climate-related disasters in developing countries not only have significant local and regional socioeconomic impacts, but they can also set back U.S. development investments, increase the need for U.S. humanitarian assistance, and affect U.S. trade and national security. U.S. citizens have long been concerned about the welfare of those living beyond U.S. borders and their vulnerability to the global impacts of climate.4,5
The impacts of climate change, variability, and extremes that occur outside the United States can directly affect the U.S. economy and trade through impacts on U.S.-owned, provided, or consumed services, infrastructure, and resources in other countries.6,7,8,9 Additionally, impacts on foreign-owned infrastructure, services, and resources can have indirect impacts on U.S. trade and businesses that rely on those assets and services, such as impacts on overseas energy and water utilities in places where U.S. international businesses are located. These foreign impacts are in addition to the impacts that climate change, variability, and extreme events within U.S. borders have on the U.S. economy and trade,10,11 as described elsewhere in the report (for example, Ch. 7: Ecosystems, KM 3).
In addition to local impacts on U.S.-owned assets abroad, climate change is expected to lead to large-scale shifts in the availability and prices of a wide array of agricultural,12,13 energy,14,15 and other goods, with corresponding impacts on the U.S. economy. These impacts occur on a wide range of timescales, ranging from months to multiple decades. For example, the prices of agricultural and mining commodities and manufactured goods are affected by year-to-year and decadal climate variations in the availability of irrigation water for agriculture or hydroelectric power.16,17,18,19 International price changes affect U.S. businesses abroad, as well as U.S. exports and imports. An example is the damaging effect that a series of short-term climate extremes in 2010 and 2011 had on global wheat production. These extremes included drought in Russia, Ukraine, and the United States and damaging precipitation in Australia. A corresponding reduction in wheat production, in combination with high demand, low stocks, trade policies, and other factors, contributed to a spike in global wheat prices.20 This benefitted U.S. wheat exports while increasing the cost of flour and bread in the United States.21 This example highlights the complex interactions that often arise through major impacts of overseas climate change, variability, or extremes on U.S. interests (see Key Message 3 for a discussion of some of the security implications from the 2010–2011 drought).22 Where these impacts increase global market prices, U.S. purchasers and consumers tend to be harmed, whereas U.S. producers tend to benefit. The opposite is generally true for impacts that drive prices down.
Overseas climate variability, extremes, and change can disrupt U.S. economic interests through impacts to overseas supply chains via impacts to international manufacturing, storage, and transportation infrastructure (road, rail, shipping, and air; Figure 16.1).23,24,25 At the same time, climate change is creating new transport opportunities, such as the potential summertime availability of trans-Arctic commercial shipping in the next few decades due to a reduction in ice cover caused by warmer temperatures,26,27,28 though the infrastructure to support this transportation pathway and its safety has not yet been developed (Ch. 26: Alaska, KM 5).
Climate risks are being increasingly recognized and reported by businesses. The Financial Stability Board’s Task Force on Climate-related Financial Disclosures (TCFD 201729) has encouraged businesses to report those risks, with hundreds of businesses currently enlisted as partners in the TCFD effort. Some U.S.-led businesses are working to reduce their climate risks abroad. One way they are doing this is through partnerships with environmental groups. For example, Starbucks and Conservation International30 have partnered to strengthen the capacity of coffee farmers and supply chains to manage climate risks,31 while Coca-Cola and the World Wildlife Fund are working together to protect foreign watersheds that Coca-Cola uses for water supply.32 Coca-Cola increased its company-wide water efficiency from 2004 to 2012 by 21.4%, which avoided approximately $600 million in costs and tended to increase resilience in the face of water shortages.33 As noted in the next section (Key Message 2), U.S. government actions are helping to promote climate resilience of infrastructure services34,35 and other factors that have the potential to create more stable conditions for American businesses operating in developing countries, as well as promoting the welfare of those countries.
Global trade can promote resilience to climate change by shifting production of goods and services to areas with more favorable climates and away from those with less favorable climates.36,37,38 However, these shifts will generally have associated costs and may have a harmful effect on communities where production is decreased.
Few studies exist that quantify the impact of climate change on U.S. corporations and the effectiveness of adaptation actions to reduce those impacts.39
U.S. development assistance helps save lives, reduce poverty, and strengthen democratic governance; it also helps societies emerge from humanitarian crises.40,41 Given their structures and levels of development, the economies and societies of developing countries are generally at greater relative risk from the impacts of climate variability, change, and extremes than are those of developed countries.1 In addition to causing suffering in developing countries, these impacts threaten to undermine U.S. investments in development and may necessitate additional humanitarian assistance (and possibly military assistance or intervention; see Key Message 3) in response to more frequent and severe natural disasters (such as flooding).
U.S. international development assistance programs, implemented either directly by U.S. government agencies (such as the U.S. Agency for International Development [USAID] and the Millennium Challenge Corporation [MCC]) or indirectly through multilateral institutions (such as the World Bank and United Nations agencies), invest in critical sectors such as agriculture, water and sanitation, health, and infrastructure. These sectors, and the U.S. investments in them, are sensitive to natural variations in climate and extremes and are vulnerable to adverse impacts of climate change.1,34,42
The U.S. government systematically identifies climate risks and seeks to reduce the vulnerability of its international development investments. For example, the MCC amended its Environmental Guidelines in June 2012 to formally adopt the International Finance Corporation’s Performance Standards on Environmental and Social Sustainability, which includes provisions on climate risk management.43,44 In addition, USAID has its own climate risk management guidelines.45 For more than a decade, the U.S. government has also funded adaptation programs that seek to reduce vulnerability to climate impacts in these critical sectors.
Developing countries are often highly vulnerable to climate extremes, which can set back development and increase the need for disaster response and recovery assistance. For example, in 1998, Hurricane Mitch devastated Honduras and Nicaragua, killing thousands of people and causing widespread damage to property and infrastructure.46 USAID and the U.S. Department of Defense (DoD) jointly responded with an immediate relief effort. USAID also reoriented many of its programs to focus on longer-term recovery.47 Climate change is likely to increase the demand for U.S. humanitarian assistance of this kind, given the expected increase in the severity of extreme events like tropical cyclones and droughts.1,48,49
Many developing countries depend heavily on agriculture as a major source of jobs and a large percentage of their gross domestic product (GDP). Drought can have impacts on food production and security at multiple scales. At the national level, the loss of food and income and the need to help farmers through bad years can set back development. At the household level, drought can wipe out crops and financial assets and leave families vulnerable to starvation.
The United States works at several levels to help countries anticipate drought and to provide farmers with tools to manage risks to their crops and finances. For example, the United States invests in early warning systems in developing countries such as the Famine Early Warning Systems Network (FEWS NET), a joint effort by multiple U.S. agencies created after a devastating drought in Ethiopia in 1984. Currently, FEWS NET works with governments and international partners in 34 countries (Figure 16.2).50 In 2015, FEWS NET warned that Ethiopia was facing its worst drought in 60 years and projected that as many as 15 million people would face acute food insecurity. Before the drought and food crisis materialized, USAID mobilized an emergency aid program and provided 680,000 metric tons of food to more than 4 million people.51
U.S. investments in making Ethiopian agriculture more climate resilient also helped individual farmers cope with the 2015 drought. A financial risk management program enables farmers to buy “weather index” insurance, which links payouts to certain indicators of extreme weather, such as drought. The insurance program uses information from FEWS NET and coordinates with Ethiopian partners as well as global reinsurance companies. More than 25,000 Ethiopian farmers who purchased this type of insurance received payouts during the drought, helping them to pay off debts, feed their families, and care for livestock.52,53 Similar index insurance products are being developed through public–private partnerships across Africa, Asia, and Latin America.
Investments by the United States towards enhancing national capacity to produce and use climate information in decision-making, also known as climate services, help countries manage their own risks and build resilience. For instance, the United States collaborated with Jamaica’s meteorological service and agriculture ministry to develop a seasonal drought forecast tailored to the needs of Jamaican farmers. Jamaican agriculture was severely affected by drought in 2014.54 Crop production losses were 57% nationally and close to 75% among farmers identifying climate risks as a major concern. However, farmers who used the drought forecast fully were able to cut their losses nearly in half that year compared to farmers who did not use or did not have access to the forecast.55
Climate-resilience investments are being made to assist other key economic sectors in developing countries, including some that are expected to have benefits over longer time frames. For instance, in the Philippines, the United States has supported six cities and provinces to consider climate impacts in the provision of water supply and wastewater treatment services. The project is improving the design, management, and maintenance of long-lived infrastructure, as well as local planning and governance.56 It assisted one water-scarce city, Zamboanga City, in developing the country’s first-ever urban water demand management plan.57
Climate change and extremes increase risks to national security through direct impacts on U.S. military infrastructure and by affecting factors, including food and water availability, that can exacerbate conflict outside U.S. borders.59,60 Droughts, floods, storm surges, wildfires, and other extreme events stress nations and people through loss of life, displacement of populations, and impacts on livelihoods.61,62 Increases in the frequency and severity of such events, as well as other aspects of climate change, may require a larger military mission focus on climate-sensitive areas such as coasts, drought-prone areas, and the Arctic.60
Climate change is already affecting U.S. Department of Defense (DoD) assets by, among other impacts, damaging roads, runways, and waterfront infrastructure.63 DoD is working to both fully understand these threats and incorporate projected climate changes into long-term planning to reduce risks and minimize impacts. There are many examples of DoD’s planning and action for risks to its assets from climate change. DoD has performed a comprehensive scenario-driven examination of climate risks from sea level rise to all of its coastal military sites,64 including atolls in the Pacific Ocean.65 In the Arctic, the U.S. Coast Guard and Navy are pursuing strategies to respond to the changing geopolitical significance resulting from the projected absence of summer sea ice in the next few decades (Ch. 2: Climate, KM 7).66,67,68,69
The risks climate change may hold for national security more broadly are connected to the relationships between climate-related stresses on societies and conflict. Direct linkages between climate-related stress and conflict are unclear,70 but climate variability has been shown to affect conflict through intermediate processes, including resource competition, commodity price shocks, and food insecurity.71,72 The potential for conflict increases where there is a history of civil violence, conflict elsewhere in the region, low GDP or economic growth, economic shocks, weak governance, and lack of access to basic needs.61 For example, droughts around the world in 2010 contributed to a doubling of global wheat prices in 2011 and a tripling of bread prices in Egypt.73 This and other factors, including national trade policy and poverty, contributed to the civil unrest that ultimately resulted in the 2011 Egyptian revolution.73 While the 2010 droughts were not the sole cause of the revolution, they contributed to destabilization of an already unstable region. Likewise, drought in Somalia has forced herders to sell livestock they could not provide for, reducing their incomes and leading some to join armed groups.74 Water scarcity and climate-related variations in water availability can increase tensions and conflict between countries.75 In these and other instances, conflict was related to stress from climate-related events, but non-climatic factors also had an important role.76,77,78,79,80,81,82,83 However, in some cases, water scarcity and variability can result in cooperation rather than conflict.61,84
Human migration is another potential national security issue. Extreme weather events can in some cases result in population displacement. For example, in 1999 the United States granted Temporary Protected Status to 57,000 Honduran and 2,550 Nicaraguan nationals in response to Hurricane Mitch.85 In 2013, more than 4 million people were internally displaced by Typhoon Haiyan in the Philippines,86 and the United States committed 13,400 military personnel to the relief effort (Figure 16.3).87 Six months after Typhoon Haiyan, more than 200,000 people remained without adequate shelter.88 While neither Hurricane Mitch nor Typhoon Haiyan was solely attributable to climate change,89 tropical cyclones are projected to increase in intensity, which would increase the risk of forced migration.2,49 Slower changes, including sea level rise and reduced agricultural productivity related to changes in temperature and precipitation patterns, could also affect migration patterns.61 However, whether migration in response to climate change will generally cause or exacerbate violent conflict is still uncertain (Ch. 27: Hawai‘i & Pacific Islands, KM 6).90,91
The shared borders of the United States are extensive. Land borders with Canada (13 states) and Mexico (4 states) include shared rivers and lakes. Maritime borders are shared with 21 countries by Hawai‘i and other island areas, including the U.S. Caribbean, the U.S.-Affiliated Pacific Islands, and the Arctic region.92,93
Climate variability and change, as well as related extreme events across shared U.S. borders, can have direct and indirect impacts on those living in the United States. For example, increased temperatures coupled with decreased precipitation in northern Mexico can lead to an increase in the intensity of dust storms and wildfires, which can cross the border into the United States.94,95,96,97,98,99 Similarly, transport of smoke from wildfires across the Canadian borders can lead to air quality and health concerns in the United States (Figure 16.4) (see also Ch. 24: Northwest, Box 24.7). Movement of fish species is affected by changes in water temperature (Ch. 9: Oceans, KM 2; Ch. 20: U.S. Caribbean, KM 2) as illustrated by the migration of Pacific hake, an economically important fish species that migrated northward from the United States to Canadian waters due to warmer ocean temperatures during the 2015 El Niño.100 Additionally, climate impacts are likely to exacerbate cross-border issues related to water, wildlife, trade, transportation, health (Box 16.1) (see also Ch. 14: Human Health), infrastructure, energy, natural resources (such as biodiversity and forests), food security, human migration, and cultural resources. Shared water resources such as rivers and lakes are particularly sensitive to changes in precipitation (Figure 16.4). In the U.S.–Mexico drylands region, large areas are projected to become drier (Ch. 23: S. Great Plains),101,102 which is expected to present increasing demands for water resources on top of existing stresses associated with population growth.103,104 Along the U.S.–Canada border, changing weather patterns along the Columbia River, which originates in Canada, affect the amount of water available for irrigation, drinking water supplies, and hydroelectric power generation.105
The management process of shared water resources is increasingly incorporating climate information into the decision-making process. Several agreements between countries have recently been restructured to consider changing weather patterns and related management challenges to include climate risk and adaptive management into their near- and long-term strategies. Along the Mexican border, the International Boundary and Water Commission, which implements water treaties between the United States and Mexico, is exploring an array of adaptive water management strategies (Ch. 25: Southwest, Box 25.1)106 and utilizes an adaptive approach that can help with managing climate-related impacts on Colorado River water.107 An example of this adaptive management approach is the design of flexible surface water and groundwater storage facilities, coupled with governance mechanisms that continuously account for changing climate conditions and water demand.
The International Joint Commission is also using adaptive management to address climate risks to U.S.–Canadian waters.108 At the subnational level, the U.S.–Canada Great Lakes Water Quality Agreement incorporated a new annex in 2012 to identify, quantify, understand, and predict the impacts of climate change on Great Lakes water quality,109 which has helped foster the binational development of new climate products for the Great Lakes (Ch. 21: Midwest, KM 3). Researchers are incorporating climate information into computer models of streamflow and reservoirs along the U.S.–Canada border to help decision-makers understand the long-term potential impacts to flood risk management, hydropower generation, and water availability in the Columbia River Basin.110 This work is led by U.S. and Canadian agencies in partnerships with academic institutions and regional entities and can be utilized to inform management over long periods of time. These examples of including climate risk into the management of shared river and lake resources can be a model for improving resilience of other shared resources, such as fisheries.
In addition to government-to-government management of transboundary resources, public–private partnerships are increasingly helping to manage climate risks associated with these resources. For example, numerous efforts exist of transboundary collaboration in the Rio Grande–Rio Bravo Basin (Ch. 23: S. Great Plains, Case Study “Rio Grande Valley and Transboundary Issues”), including a bilateral public–private partnership that has implemented collaborative science, restoration, and monitoring actions to restore the river, with climate adaptation as one of the objectives. The partnership consists of businesses, nongovernmental conservation organizations, federal and state agencies, academic institutions, private foundations, and the public from both Mexico and the United States.104,111,112,113 The U.S. Caribbean (Ch. 20: U.S. Caribbean, KM 6) and Hawai‘i and the Pacific Islands (Ch. 27: Hawaiʻi & Pacific Islands) are actively engaged with international partners to build adaptive capacity and reduce risks associated with climate change uncertainty at the regional level. Such international engagement may be more in demand in the future to address increasing vulnerabilities of transboundary resources.
The Fourth National Climate Assessment (NCA4) is the first U.S. National Climate Assessment (NCA) to include a chapter that addresses the impacts of climate change beyond the borders of the United States. This chapter was included in NCA4 in response to comments received during public review of the Third National Climate Assessment (NCA3) that proposed that future NCAs include an analysis of international impacts of climate change as they relate to U.S. interests.
This chapter focuses on the implications of international impacts of climate change on U.S. interests. It does not address or summarize all international impacts of climate change; that very broad topic is covered by Working Group II of the Intergovernmental Panel on Climate Change (IPCC; e.g., IPCC 20141). The U.S. government supports and participates in the IPCC process. The more focused topic of how U.S. interests can be affected by climate impacts outside of the United States is not specifically addressed by the IPCC.
The topics in the chapter—economics and trade, international development and humanitarian assistance, national security, and transboundary resources—were selected because they illustrate ways in which U.S. interests can be affected by international climate impacts. These topics cut across the world, so the chapter does not focus on impacts in specific regions.
The transboundary section was added to address climate-related impacts across U.S. borders. While the regional chapters address local and regional transboundary impacts, they do not address impacts that exist in multiple regions or agreements between the United States and its neighbors that create mechanisms for addressing such impacts.
The science section is part of the chapter because of the importance of international scientific cooperation to our understanding of climate science. That topic is not treated as a separate section because it is not a risk-based issue and therefore not an appropriate candidate to have as a Key Message.
The U.S. Global Change Research Program (USGCRP) put out a call for authors for the International chapter both inside and outside the Federal Government. The USGCRP asked for nominations of and by individuals with experience and knowledge on international climate change impacts and implications for the United States as well as experience in assessments such as the NCA.
All of the authors selected for the chapter have extensive experience in international climate change, and several had been authors on past NCAs. Section lead assignments were made based on the expertise of the individuals and, for those authors who are current federal employees, based on the expertise of the agencies. The author team of ten individuals is evenly divided between federal and non-federal personnel.
The coordinating lead author (CLA) and USGCRP organized two public outreach meetings. The first meeting was held at the Wilson Center in Washington, DC, on September 15, 2016, as part of the U.S. Agency for International Development’s (USAID) Adaptation Community Meetings and solicited input on the outline of the chapter and asked for volunteers to become chapter authors or otherwise contribute to the chapter. A public review meeting regarding the International chapter was held on April 6, 2017, at Chemonics in Washington, DC, also as part of USAID’s Adaptation Community Meetings series. The USGCRP and chapter authors shared information about the progress to date of the International chapter and sought input from stakeholders to help inform further development of the chapter, as well as to raise general awareness of the process and timeline for NCA4.
The chapter was revised in response to comments from the public and from the National Academy of Sciences. The comments were reviewed and discussed by the entire author team and the review editor, Dr. Diana Liverman of the University of Arizona. Individual authors drafted responses to comments on their sections, while the CLA and the chapter lead (CL) drafted responses to comments that pertained to the entire chapter. All comments were reviewed by the CLA and CL. The review editor reviewed responses to comments and revisions to the chapter to ensure that all comments had been considered by the authors.