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ISR Research

(Un)Managed Retreat? Perspectives on Biophysical and Social Dynamics of Coastal Retreat on O‘ahu, Hawaiʻi

As an island community with world famous beaches, Hawaiʻi’s coastal managers face significant challenges in the face of sea level rise (SLR). Shoreline laws have recently been updated to limit further shoreline hardening, making Hawaiʻi a salient case study to understand the challenges and opportunities around managed retreat. We interviewed 42 private sector, civil society, and government actors involved with coastal governance and anchored our conversations to three distinct communities on O‘ahu. Factors that affected participant perspectives on the viability of retreat per site hinged on: 1) physical/natural barriers and opportunities; 2) perceptions of the public value of a beach; 3) the importance of existing infrastructure; and 4) the political influence of coastal homeowners. Participants’ views on who should inform the coastal planning process moving forward varied by site. In addition to residents, there was largely agreement that communities should include those with affinity and long-standing relationships with place.

Read the article.

The Risks of Sea Level Rise: Perceptions and Policy Preferences among Hawaiʻi’s Elected Officials

Due to its remote geographic location and extensive coastlines, the State of Hawaiʻi is particularly vulnerable to climate change and sea level rise (SLR). While Hawaiʻi was among the first states to officially recognize the climate crisis and has played a leading role in combating climate change, the state is still developing plans to implement coastal adaptation policies that address the predicted impacts of SLR. This survey explores the views of Hawaiʻi’s elected representatives regarding the risks of SLR and their favored approaches to adaptation.

The report presents the results of an online survey conducted between June and September of 2023, which was sent to all currently elected officials in the Hawaiʻi State Legislature and the State’s four County Councils. Findings reveal a significant disconnect between belief and behavior: on the one hand, Hawaiʻi’s policymakers perceive an extremely high level of risk concerning sea level rise; on the other hand, they do not rank it as a top policy priority.

Read the final perceptions and policy preferences report.

A Study of Shoreline Regulations and Managed Retreat for Hawaiʻi: A Cost Analysis for Paumalū, Oʻahu

Coastal communities are at-risk of the consequences of sea level rise (SLR) with threats to people, infrastructure, and ecosystems. The Hawaiian Islands are already experiencing the impacts of SLR, including exacerbated effects of coastal erosion, storm surge, and coastal flooding. Beaches in Hawaiʻi are protected as a public trust resource. However, many beaches are experiencing chronic erosion and overall beach loss. To contribute to an understanding of SLR response for Hawaiʻi, this report reviews Hawaiʻi’s shoreline regulations and identifies SLR adaptation options and mechanisms to implement managed retreat of coastal development in the context of residential areas adjacent to sandy beaches. Using a case study from the North Shore of Oʻahu, this report assesses the costs and tradeoffs of three types of retreat (all-at-once, threshold-based, and reactive) through the year 2100.

Read the final Shoreline Regulations and Managed Retreat for Hawaiʻi report. (Note: if you require accessibility accommodation with this report please contact for assistance). Read the complementary article.

Sea Level Rise Risk Interactions with Coastal Property Values: a Case Study of Oʻahu, Hawaiʻi

Climate change-induced sea level rise (SLR) will affect a range of coastal assets and prompt difficult decisions about coastal land use across the world. Several recent studies find that current and projected SLR is associated with relatively lower property values. We contribute to this growing body of research with a case study of Oʻahu, Hawaiʻi, which is famed for its beaches as well as valuable coastal real estate. We leverage a dataset that unpacks multiple types of SLR exposure and coastal parcel attributes. We apply property transaction data for the island of Oʻahu through 2019 to investigate the effect of current and expected SLR exposure on residential property prices. We find that exposed properties have already experienced declines in transaction prices, at 9 to 14%, attributed to expectations of exposure to chronic inundation (as opposed to seasonal flooding). The price declines are mainly for multi-dwelling homes as opposed to single family homes. The market response of residential properties to O‘ahu has important implications for coastal management strategies, in particular the viability and timing of programs for retreat.

Read the article.

Hawaiʻi GHG Emissions Projections, 2020–2045

ISR and researchers with UHERO have partnered with ICF International to develop Hawaiʻi’s Greenhouse Gas (GHG) Emissions Reports for the State Department of Health over the next three years. These reports include inventories of past emissions and projections of future emissions. ISR and UHERO contribute to forecasting future emissions, as GHG emissions are a representation of economic activities, technology and land use. Forecasts take into account existing policies and trends per sector. The forthcoming report will forecast emissions through the year 2045.

Read prior Hawaiʻi GHG inventories and projections.

Economic and GHG Impacts of a U.S. State-level Carbon Tax: the Case of Hawaiʻi

In the absence of sustained federal leadership to address climate change, many U.S. states and cities have implemented their own climate policies. In 2018, the State of Hawaiʻi set a goal of sequestering more greenhouse gasses (GHG) annually than emitted no later than 2045. This study builds an economic model to understand how a state-level carbon tax in Hawaiʻi could contribute to meeting this objective and how it would change household welfare for five different income groups. Against a baseline of existing federal and state GHG-related policies, the study finds that if Hawaiʻi were to adopt a carbon tax at the level of the 2021 federally-specified social cost of carbon, Hawaiʻi’s cumulative emissions would decline by an additional 10% from 2025 to 2045. Changes in group welfare depend heavily on whether carbon tax revenues are paid to households as equal-share dividends or used for increased state spending. If revenues are returned to households, the tax is progressive and benefits the average household in all five income groups. This is primarily because visitors pay the carbon tax while on a Hawaiʻi vacation; their contributions amount to approximately one-third of collected revenues. These findings are relevant to tourism-intensive regions, economies with demand-inelastic GHG-intensive export sectors, and island economies.

Read the full article on economic and GHG impacts.

Managing for Diverse Coastal Uses and Values under Sea Level Rise: perspectives from Oʻahu, Hawaiʻi

Effective and equitable coastal decision-making under sea level rise (SLR) requires managing for multiple coastal uses and values. This study explores how coastal decision-makers in Hawaiʻi perceive diverse uses and values of beaches and coastlines to be important and how they see recognition of these uses and values ideally shaping SLR response. We conducted 42 interviews and 37 surveys with representatives from government, private, and civil society organizations involved with coastal decision-making across the state. To understand how perspectives change based on localized contexts, we grounded our conversations around three socio-ecologically distinct communities on the island of Oʻahu: Kaʻa‘awa, Sunset Beach, and Kāhala. We found broad agreement across decision-maker groups and sites in the perception that current coastal management decisions prioritize private and monetary (particularly real estate) values over diverse social and ecological values, often to the detriment of beaches and coastal communities. Though participants generally agreed on the need for new policy and management approaches that promote protection of relational and other non-monetary values of beaches to diverse communities, interviewees held markedly different perceptions over whether, and the extent to which, sustaining beaches under SLR necessitates tradeoffs in maintaining private property claims. Results highlight the importance of approaching SLR adaptation with an appreciation of multiple and place-based uses and values; and of developing processes to build a shared understanding among distinct actor groups and value systems of the tradeoffs inherent in SLR response.

Read the full article on managing for diverse coastal uses.

Carbon Pricing Assessment for Hawaiʻi, Economic and Greenhouse Gas Impacts

Climate change threatens many of Hawaiʻi’s human and natural systems, including coral reefs, beaches, and biodiversity. Sea level rise alone is expected to cost $19 billion in loss of land and structures, in addition to an unknown cost associated with damage to critical infrastructure (Hawaiʻi Climate Change Mitigation and Adaptation Commission, 2017). Minimizing these impacts requires a drastic shift globally from greenhouse gas (GHG) intensive activities to greener technologies and behaviors. Mitigating the causes of climate change is fundamentally a collective action problem. Though Hawaiʻi is a small GHG emitter on a global scale, on a per capita basis Hawaiʻi residents emit more than twice the global average. In 2018 the State of Hawaiʻi passed Act 15, which set a goal of sequestering more GHGs annually than produced. Act 15 aims to do so “as quickly as practicable, but no later than 2045” (HRS §225P-5). This study explores the role of a state-level carbon tax in helping to meet this goal. It uses a comprehensive model of Hawaiʻi’s economy and GHG emissions through the year 2045 to understand the economic and GHG impacts of different carbon tax rates and ways to use the tax revenue.

Read the full article on carbon pricing assessment.

Does Air Pollution Increase Electric Vehicle Adoption? Evidence from U.S. Metropolitan Areas, 2011–2018

We estimate a model of electric vehicle (EV) adoption in 427 of the largest metropolitan areas in the 48 contiguous U.S. states. We observe all new battery electric vehicles (BEV) and plug-in electric vehicles (PHEV) registrations by metro area over the 2011–2018 period, and we investigate whether adoption of new EVs is statistically related to multiple types of air pollution — long-term air pollution as measured by ambient PM2.5 and temporary pollution events as measured by the presence of wildfire smoke plumes in either the lower or upper atmosphere. Regression results show that both ambient PM2.5 and smoke plumes are related to BEV and PHEV adoptions by metro area.

Read the full article on air pollution and electric vehicle adoption.

One Climate One Oʻahu Climate Action Plan 2020-25

The One Climate One Oʻahu Climate Action Plan 2020–25 (CAP) was released in April 2021. The CAP is a science-based, community-driven strategy for Oʻahu to combat climate change and eliminate fossil fuel emissions—the root cause of global warming. The action plan was a joint effort by the Honolulu City and County Office of Climate Change, Resiliency and Sustainability, the University of Hawaiʻi at Mānoa Institute for Sustainability and Resiliency (ISR) and the UH Economic Research Organization (UHERO). The plan lays out a detailed list of programs, policies and actions that Oʻahu can take to reduce greenhouse gas emissions by 45 percent over the next five years on the path to carbon neutrality by 2045. The plan’s release was the culmination of a community input process launched by the City’s Office of Climate Change, Sustainability and Resiliency in July 2018 which included a series of island-wide community meetings to inform residents about the urgency of climate action and collect their ideas and concerns to be incorporated into the plan.

Read the full Climate Action Plan.

Climate Change and Social Vulnerability Framework

The State of Hawaiʻi Climate Commission was created by Act 32 in 2017. It aims to promote “ambitious, climate-neutral, culturally responsive strategies for climate change adaptation and mitigation in a manner that is clean, equitable and resilient.” To better inform its aim towards equitable approaches within climate response, ISR helped the Commission build an understanding of social vulnerability to climate change, through a review of frameworks, data and indicators.

Read more about Climate Change and Social Vulnerability.

Sea Level Rise Learning Trip

The “SLR Learning Trip” was organized between the Institute for Sustainability and Resilience (ISR) at the University of Hawaiʻi at Mānoa and the Hawaiʻi Philanthropy Forum, with funding from the Harold K.L Castle Foundation and the David and Lucile Packard Foundation. In the fall of 2019, the trip took a delegation of Honolulu City & County and Hawaiʻi State officials to Miami, Charleston, and Boston for a tour organized around the theme of adaptation to chronic flooding.

Sea Level Rise Learning Trip Summary Report [PDF]

Supporting Local Climate Policy

Healy Foundation-Funded Research Assistantship

The Healy Foundation generously supports a research assistant position in the ISR. For the 2021-2022 academic year, funds from the Healey Foundation supported the work of Ryan Ringuette in conducting research and providing other support for the City and County of Honolulu Climate Change Commission. Ryan continued important work being done the year before by Rachael Han, whose position was also supported by the Healey Foundation.

Campus Sustainability and Resilience Initiatives

Sustainability Tracking, Assessment and Rating System (STARS) Submission

The Institute for Sustainability and Resilience (ISR) assisted the University of Hawaiʻi Office of Sustainability to prepare and submit the inaugural Sustainability Tracking, Assessment & Rating System (STARS) report in March 2022 for the Mānoa campus. STARS is a program of the Association for the Advancement of Sustainability in Higher Education (AASHE) and is a transparent self-reporting framework for colleges and universities to measure their sustainability performance. We were pleased to find that campus-wide sustainability efforts earned the Mānoa campus a bronze designation for our inaugural submission. ISR looks forward to contributing to future submissions as we strive to advance sustainability initiatives across campus while increasing future rankings.

Please view the online version of the submission.

UHM-COFA Intersections Workshop

The Office of the Provost, Institute of Sustainability and Resilience (ISR) and Center for Pacific Island Studies (CPIS) co-hosted a meeting in July 2019 of faculty, staff, and researchers at the University of Hawaiʻi at Mānoa (UHM) who work and/or conduct research in Island nations whose relations with the United States are governed by bilateral treaties generally referred to as the Compacts of Free Association (COFA). ISR aims to foster cross-campus, multidisciplinary curricular programs and research in sustainability and resilience, organized under the Office of the Provost.

Intersections Workshop Summary Report [PDF]

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