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finding 16.3 : key-message-16-3
Climate change, variability, and extreme events, in conjunction with other factors, can exacerbate conflict, which has implications for U.S. national security (medium confidence). Climate impacts already affect U.S. military infrastructure, and the U.S. military is incorporating climate risks in its planning (high confidence).
This finding is from chapter 16 of Impacts, Risks, and Adaptation in the United States: The Fourth National Climate Assessment, Volume II.
Process for developing key messages:
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 2014c390e13f-8517-40a9-a236-ac4dede3a7a0). 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.
Description of evidence base:
Based on an assessment of a wide range of scientific literature on climate and security, multiple national security reports have framed climate change as a stressor on national security.b00dec8c-2a2a-415d-a951-58304a00fc62,e24bffd2-beaa-4f02-be7e-e4c9ecd6c9f1,9e7e9908-727f-46a6-90da-0a7f078293ed,a93863d9-adb6-4264-bfb3-ace73b3c2077,28058e45-1a62-4fa4-95e5-39dbefb51944,c175b9db-aea1-4441-9e72-7b8e11825693,5b76182a-549a-4148-b4bb-017e09e572f8 A large body of research has examined how stress due to adverse climatic conditions may affect human and national security in relation to conflict. While a few studies clearly link climatic stress to insecurity conflict,8816e89b-8604-4ebf-9646-13b7352a2ecd,6013994a-8717-4a99-935a-8a13800fcdc5 more often studies do not find a measurable direct response.32ad430a-4769-4e16-8ece-c28d123504b0,e991b433-572b-40a2-8ab4-dfc9ab520152,7b1fc35e-bf68-443f-a11a-272be556be6e,6b8104da-6197-461f-b530-f73b42d81f08,069f4158-18f0-475d-a33e-8b21a935be8c,43c748af-a9cb-4b66-b0fc-db7569cb637b,acbba036-70c4-4a6b-9562-21aa70ef606a,e4456b15-44b5-45d0-a92d-36f7be665121 Instead, the relationship between climate and conflict is often framed as climate stress affecting conflict through intermediate processes, including commodity price shocks and food and water security, which are themselves documented stressors on conflict.d5216e42-45ce-457b-bda8-b2e445d23c0d,afad9e4f-64a9-42fd-b132-a63493a6520b,502dae25-1744-4257-bb04-c9793af9bea3 Many studies focus on Africa, but evidence exists throughout the world.21dfc644-70cb-4784-a6fb-df36f23bf7da,e991b433-572b-40a2-8ab4-dfc9ab520152,c9399cc5-7555-47d7-951e-063a334a79b1,e705ebf7-ae07-4f77-b55f-ae678cafd841,a056f0e9-460b-4775-a338-a4b10e98c639,7b1fc35e-bf68-443f-a11a-272be556be6e,5592b6e0-1793-4ad7-89cd-e979f53e7d22 Additional complexity arises from evidence of a range of societal responses to resource scarcity such as that brought on by climate change and natural variability.d5216e42-45ce-457b-bda8-b2e445d23c0d
The U.S. military is observing climate change impacts to its infrastructure and is taking a scenario-driven, risk-based approach to address resultant challenges. Exceedance probability plots of the type used to support engineering siting and design analysis were used but modified to include responses to time-specific tidal phases and historical trends to create an estimate of the “present day” exceedance probability. The hindcast projections kept pace with an Intermediate-Low sea level rise scenario of approximately 5 mm/year (about 0.2 inches/year).af1f3f53-c612-4dcb-9c28-31c859d5a03e The focus for Department of Defense (DoD) infrastructure management, however, is the resultant increased trend for exceedances that would challenge infrastructure functional integrity (such as negative impacts to critical roadways and airfields).af1f3f53-c612-4dcb-9c28-31c859d5a03e In an effort to understand risks to the integrity of coastal facilities more broadly, the DoD uses a scenario-driven risk management approach to support decision-making regarding its coastal installations and facilities. The scenario approaches provide a framework for the inherent uncertainties of future events while providing decision support. Scenarios are not simply predictions about the future but rather plausible futures bounded by observations and the constraints of physics. Using scenarios, decision-makers can then examine risks through the lens of event impacts, costs of additional analysis, and the results of inaction. In this way, inaction is recognized as an important decision in its own right.d2dc9855-41bc-4e94-bb79-f0ba2ff2684b
New information and remaining uncertainties:
The impact and risk of conflict related to climate change is difficult to separate from other drivers of environmental vulnerability, including economic activity, education, health, and food security.d5216e42-45ce-457b-bda8-b2e445d23c0d,32ad430a-4769-4e16-8ece-c28d123504b0 There is currently a lack of robust theories that fully explain causality and associations between climate change and conflict.
Datasets on climate change, conflict, and security are often limited in length and pose statistical difficulties.32ad430a-4769-4e16-8ece-c28d123504b0 However, recent advances in statistical analysis have begun to allow the quantification of indirect effects of multiple variables connecting climatic pressures and violence.fef51b51-9036-4b22-98ba-94d9159a2514 These results are preliminary, mostly due to a lack of necessary data and the difficulty of quantifying relevant social variables, such as identity politics or grievances. There is a widespread pattern of examining instances of conflict for drivers, precluding the possibility of finding that climate-related stressors did not result in conflict. There is a need to analyze situations where no conflict occurred despite existing climate risks. Intercomparison of quantitative studies of the link between conflict and adverse climate conditions is complicated because the wide range of climatic and social indicators differ in spatial and temporal coverage, often due to a lack of data availability. Prehistoric and premodern evidence of the impact of climate change on conflict is not necessarily relevant to modern societies,069f4158-18f0-475d-a33e-8b21a935be8c and some of the climate shifts currently being faced are unprecedented over centuries to millennia.e4456b15-44b5-45d0-a92d-36f7be665121 Therefore, the possible existence of a relationship is better understood than its particulars and is best expressed in the formulation that climate extremes and change can exacerbate conflict.
The ongoing Syrian conflict is often framed in terms of climate change. However, it is not possible to draw conclusions on the role of climate in the outcome of an ongoing conflict. Moreover, the role of climate variability (such as drought), the contribution of climate change to such variability, and the contribution of climate variability to the subsequent conflict is a matter of active debate in the assessed literature.cb442681-f8b0-4d84-821e-402ce5367991,36d50d6d-ed82-4564-8524-7c09e1e9fcee,c0d79035-8cae-4c0b-86eb-71f28995f0c4,c2b74393-2ff9-40ff-878f-5cd81e4f6326
The documented impacts of climate on national security largely occur through processes associated with natural climate variability, such as drought, El Niño, and tropical storms. While observed and projected increases in extreme weather and climate events have been attributed to climate change, uncertainty remains.a29b612b-8c28-4c93-9c18-19314babce89,f03117be-ccfe-4f88-b70a-ffd4351b8190,77026696-4273-40c2-9226-05e83bdf7ea9,2180df56-f5ec-49e5-9733-d61778bf49d1
Similarly, additional studies are underway to determine the potential impacts of climate change on DoD resources and mission capabilities. Many of these efforts seek to assess the vulnerability of infrastructure to climate change across a wide variety of ecosystems.cf17e1a8-88d4-4e55-ba9f-6a6ce1c1d2ab,9aa16b15-c1b0-4dec-9442-01cd91e62f35,45fb3cf0-eb2e-465c-9954-0bfb942a9d18
Assessment of confidence based on evidence:
There is consensus on framing climate as a stressor on other factors contributing to national security. Given the knowledge of factors that increase the risk of civil wars, and evidence that some of these factors are sensitive to climate change, the IPCC found justifiable concern that “climate change or changes in climate variability [could] increase the risk of armed conflict in certain circumstances.”d5216e42-45ce-457b-bda8-b2e445d23c0d However, the literature examining specific causality does not result in a high confidence conclusion to link climate and conflict, which is reflected in the Key Message medium confidence assignment. Multiple schools of thought exist on the mechanisms and degree of linkages, and models are incomplete. Data are improving and evidence continues to emerge, but the inconsistent evidence limits our ability to assign a probability to this Key Message.
Nonetheless, with regard to climate impacts on physical infrastructure, the DoD observes changes in the infrastructure at its installations that are consistent with climate change. In keeping with sound stewardship and prudence, it uses scenario-driven approaches to identify areas of risk while continuing to research and provide resilient responses to the observed changes.
ProvenanceThis finding was derived from scenario rcp_4_5
This finding was derived from scenario rcp_8_5
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