--- chapter: doi: 10.7930/NCA4.2018.CH29 identifier: mitigation-avoiding-and-reducing-long-term-risks number: 29 report_identifier: nca4 sort_key: 129 title: Reducing Risks through Emissions Mitigation url: https://nca2018.globalchange.gov/chapter/29 chapter_identifier: mitigation-avoiding-and-reducing-long-term-risks cited_by: [] confidence: '

There is very high confidence that the dual strategies of mitigation and adaptation being taken at national, regional, and local levels provide complementary opportunities to reduce the risks posed by climate change. Studies consistently find that adaptation would be particularly important for impacts occurring over the next several decades, a time period in which the effects of large-scale mitigation would not yet be easily recognizable. However, further analysis is needed to help resolve uncertainties regarding the timing and magnitude of adaptation, including the potential positive and negative co-effects with mitigation.

' contributors: [] evidence: "

Global-scale reductions in GHG emissions are projected to reduce many of the risks posed by climate change. However, Americans are already experiencing, and will continue to experience, impacts that have already been committed to because of past and present emissions.{{< tbib '5' '9f559c9b-c78e-4593-bcbe-f07661d29e16' >}}^,{{}} In addition, multisector modeling frameworks demonstrate that mitigation is unlikely to completely avoid the adverse impacts of climate change.^{{{< tbib '2' '0b30f1ab-e4c4-4837-aa8b-0e19faccdb94' >}}^,{{}}^,{{}}^,{{}}^,{{}}} These factors will likely necessitate widespread adaptation to climate change (Ch. 28: Adaptation); an expanding literature consistently indicates potential for the reduction of long-term risks and economic damages of climate change.{{< tbib '2' '0b30f1ab-e4c4-4837-aa8b-0e19faccdb94' >}}^,{{}}^,{{}}^,{{}} However, it is important to note that adaptation can require large up-front costs and long-term commitments for maintenance (Ch. 28: Adaptation), and uncertainty exists in some sectors regarding the applicability and effectiveness of adaptation in reducing risk.{{< tbib '101' '6f504af2-a3a0-46c3-a8bd-9f5f266bd5bf' >}}

Because of adaptation’s ability to reduce risk in ways that mitigation cannot, and vice versa, the weight of the evidence shows that the two strategies can act as complements. Several recent studies jointly model the effects of mitigation and adaptation in reducing overall risk to the impacts of climate change in the United States, focusing on infrastructure (e.g., Larsen et al. 2017, Melvin et al. 2016, Neumann et al. 2014)^{{{< tbib '71' '5b27123a-8c6d-4e85-bd48-841436fdf9eb' >}}^,{{}}^,{{}}} and agriculture (e.g., Kaye and Quemada 2017, Challinor et al. 2014, Lobell et al. 2013).{{< tbib '108' '94c2d912-8ac9-4c32-958c-6918f5cc079a' >}}^,{{}}^,{{}} Exploration of this mitigation and adaptation nexus is also advancing in the health sector, with both mitigation and adaptation (such as behavioral changes or physiological acclimatization) being projected to reduce deaths from extreme temperatures{{< tbib '100' '1ad1d794-bc57-4e48-ab28-0e2b65767cb9' >}} in both the higher and lower emissions scenarios that are the focus of this chapter. Similarly, energy efficiency investments are reducing GHG emissions and operating costs and improving resilience to future power interruptions from extreme weather events (Ch. 14: Human Health). While more studies exploring the joint effects of mitigation and adaptation are needed, recent literature finds that combined mitigation and adaptation actions can substantially reduce the risks posed by climate change in several sectors.{{< tbib '2' '0b30f1ab-e4c4-4837-aa8b-0e19faccdb94' >}}^,{{}}^,{{}} However, several studies highlight that mitigation and adaptation can also interact negatively. While these studies are more limited in the literature, sectors exhibiting potential negative co-effects from mitigation and adaptation include the bioenergy–water resource nexus{{< tbib '114' '9bfd3c12-a45e-4317-b640-6deadff2a790' >}} and changes in electricity demand and supply in response to increased use of air conditioning.{{< tbib '2' '0b30f1ab-e4c4-4837-aa8b-0e19faccdb94' >}}^,{{}}

" files: [] gcmd_keywords: - definition: 'An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system. These biotic and abiotic components are regarded as linked together through nutrient cycles and energy flows. As ecosystems are defined by the network of interactions among organisms, and between organisms and their environment, they can be of any size but usually encompass specific, limited spaces. (although some scientists say that the entire planet is an ecosystem.' href: https://data.globalchange.gov/gcmd_keyword/f1a25060-330c-4f84-9633-ed59ae8c64bf.yaml identifier: f1a25060-330c-4f84-9633-ed59ae8c64bf label: ECOSYSTEMS parent_identifier: 91c64c46-d040-4daa-b26c-61952fdfaf50 uri: /gcmd_keyword/f1a25060-330c-4f84-9633-ed59ae8c64bf - definition: |- Mitigation includes any activities that prevent a hazard emergency, reduce the chance of an emergency happening, or lessen the damaging effects of unavoidable emergencies. href: https://data.globalchange.gov/gcmd_keyword/a2e9c7b9-96fd-449f-91db-7ab5e2dd679e.yaml identifier: a2e9c7b9-96fd-449f-91db-7ab5e2dd679e label: HAZARDS MITIGATION parent_identifier: 464de0a5-2bb9-4172-9fd3-1634cbc4e739 uri: /gcmd_keyword/a2e9c7b9-96fd-449f-91db-7ab5e2dd679e - definition: |- Planning refers to the formulation of a course of action to be taken in the event of a hazard emergency. href: https://data.globalchange.gov/gcmd_keyword/5c14b001-518f-460b-90fe-139bf192d1f2.yaml identifier: 5c14b001-518f-460b-90fe-139bf192d1f2 label: HAZARDS PLANNING parent_identifier: 464de0a5-2bb9-4172-9fd3-1634cbc4e739 uri: /gcmd_keyword/5c14b001-518f-460b-90fe-139bf192d1f2 - definition: 'The science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals.' href: https://data.globalchange.gov/gcmd_keyword/da2c70fd-d92b-45be-b159-b2c10cb387c6.yaml identifier: da2c70fd-d92b-45be-b159-b2c10cb387c6 label: PUBLIC HEALTH parent_identifier: fb93d937-c17c-45d0-a9e3-ca5c8a800ca8 uri: /gcmd_keyword/da2c70fd-d92b-45be-b159-b2c10cb387c6 - definition: 'Climate Change Impact Assessment Models examine and predict the vulnerabilities of human populations to future climate change, including associated sea-level rise and changes in the frequency and intensity of climate extremes such as floods, droughts, heat waves and windstorms, and taking into account potential impacts on water resources, agriculture and food security, human health, coastal and other types of settlements, and economic activities. 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The scope for this chapter was determined by the federal Fourth National Climate Assessment (NCA4) Steering Committee, which is made up of representatives from the U.S. Global Change Research Program (USGCRP) member agencies (see App. 1: Process for more information regarding the Steering Committee). The scope was also informed by research needs identified in the Third National Climate Assessment (NCA3) and in subsequent gap analyses.{{< tbib '155' 'd6eb34ef-1bfb-4b90-a397-f6bb363086a0' >}} Prospective authors were nominated by their respective agency, university, organization, or peers. All prospective authors were interviewed with respect to their qualifications and expertise. Authors were selected to represent the diverse perspectives relevant to mitigation, with the final team providing perspectives from federal and state agencies, nonfederal climate research organizations, and the private sector. The author team sought public input on the chapter scope and outline through a webinar and during presentations at conferences and workshops.

The chapter was developed through technical discussions of relevant evidence and expert deliberation by the report authors during extensive teleconferences, workshops, and email exchanges. These discussions were informed by the results of a comprehensive literature review, including the research focused on estimating the avoided or reduced risks of climate change. The authors considered inputs submitted by the public, stakeholders, and federal agencies and improved the chapter based on rounds of review by the public, National Academies of Sciences, Engineering, and Medicine, and federal agencies. The author team also engaged in targeted consultations during multiple exchanges with contributing authors from other chapters of this assessment, as well as authors of the Climate Science Special Report (CSSR). For additional information on the overall report process, see Appendix 1: Process.

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Interactions between mitigation and adaptation are complex and can lead to benefits, but they also have the potential for adverse consequences (very high confidence). Adaptation can complement mitigation to substantially reduce exposure and vulnerability to climate change in some sectors (very high confidence). This complementarity is especially important given that a certain degree of climate change due to past and present emissions is unavoidable (very high confidence).

' uncertainties: '

It is well understood that adaptation will likely reduce climate risks and that adaptation and mitigation interact. However, there are uncertainties regarding the magnitude, timing, and regional/sectoral distribution of these effects. Developing a full understanding of the interaction between mitigation and adaptation, with detailed accounting of potential positive and negative co-effects, is an important research objective that is only beginning to be explored in the detail necessary to inform effective implementation of these policies. Quantifying the effectiveness of adaptation requires detailed analyses regarding the timing and magnitude of how climate is projected to affect people living in the United States and their natural and built environments. As such, the uncertainties described under Key Messages 1 and 2 are also relevant here. Further, uncertainty exists regarding the effectiveness of adaptation measures in improving resilience to climate impacts. For some sectors, such as coastal development, protection measures (for example, elevating structures) have been well studied and implemented to reduce risk. However, the effectiveness of adaptation in other sectors, such as the physiological response to more intense heat waves, is only beginning to be understood.

' uri: /report/nca4/chapter/mitigation-avoiding-and-reducing-long-term-risks/finding/key-message-29-4 url: ~