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Climate Action

ISR research on Climate Action studies policies to reduce greenhouse gas emissions, measures emissions over time and for alternative futures, and develops plans to implement change. A summary of recent projects and publications are provided below, as well as additional archived resources.

Hawaiʻi GHG Emissions Projections for 2020-2045

ISR, UHERO and ICF International partnered to develop Hawaiʻi’s Greenhouse Gas (GHG) Emissions Reports for the State Department of Health, for inventory years 2015 through 2022. In addition to a full accounting of the State's GHGs, ISR and UHERO developed forecasts of future emissions based on alternative future scenarios related to economic activities, technology and land use. 

Economic Feasibility of Agrivoltaic Systems for Sustainable Small Scale Farming (2025)

Co-location of agricultural and energy can achieve land use efficiency and minimize land use conflict within the renewable energy transition. This study tested agrivoltaic (AV) systems, crops growth under solar PV panels, for lettuce varieties to better understand financial viability of systems in Hawai‘i. This report was published in Food and Energy Security in 2025.

Agrivoltaic Paper

Energy Conservation and Emissions Reduction

ISR partnered with ICF International, Walker Consultants and the City and County of Honolulu Office of Climate Change, Sustainability and Resiliency to develop a transportation-focused energy and emissions reduction plan for O‘ahu.

Emissions Reduction Plan

Economic and GHG Impacts of US State-level Carbon Tax: The Case of Hawaiʻi (2022)

This article presents an economic model to understand how a state-level carbon tax could reduce greenhouse gas (GHG) and how it would change household welfare for five different income groups. 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 revenues are paid directly to households.

Carbon Tax Paper

Carbon Pricing Assessment for Hawai‘i: Economic and GHG Impacts (2021)

In 2018, the State of Hawaiʻi passed Act 15, which set a goal of sequestering more GHGs annually than produced by 2045. This report explores the role of a state-level carbon tax in helping to meet this goal, including analysis of complementary policy mechanisms. This report was completed in response to Act 122 (2019). Another study builds on the initial report by adding additional scenarios for carbon tax revenue use and redistribution, and considerations for administrative aspects of new tax policy including impacts to non-tax filers.

One Climate One Oʻahu Climate Action Plan 2020-25

The 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 climate change. The action plan was a joint effort by the Honolulu City and County Office of Climate Change, Resiliency and Sustainability, ISR and UHERO. 

Coffman, M., Bernstein, P., Schjervheim, M., Lacroix, S., and Hayashida, S. (2023). A Comparison of State-Level Carbon Reduction Strategies: A Case Study of Hawai‘i. Energy and Climate Change, 4. https://doi.org/10.1016/j.egycc.2023.100100.  

Bayham, J., Burkhardt, J., Coffman, M., Hayashida, S., and La Croix, S. (2022). Does Air Pollution Increase Electric Vehicle Adoption? Evidence from US Metropolitan Areas, 2011-2018. Journal of Environmental Economics and Policy. https://doi.org/10.1080/21606544.2022.2059015.

Ko, Y. and Coffman, M. (2022). Renewable Energy Landscapes Across the Pacific Rim. Section 5, Chapter 30. The Routledge Handbook of Sustainable Cities and Landscapes in the Pacific Rim. Eds. Yizhao Yang and Anne Taufen.

Wee, S., LaCroix, S., and Coffman, M. (2021). Understanding Changes in Electric Vehicle Policies in the U.S. States, 2010-2018. Transport Policy 103: 211-223. https://doi.org/10.1016/j.tranpol.2021.01.011.

Coffman, M. (2020). Air Pollution and the Pandemic: How Will COVID-19 Shape Hawai‘iʻs Response to Global Climate Change? Value of Hawai‘i, Volume 3. University of Hawai‘i Press.

Wee, S., Coffman, M., Allen, S. (2020). EV Driver Characteristics: Evidence from Hawai‘i. Transport Policy, 80: 33-40. https://doi.org/10.1016/j.tranpol.2019.12.006.

Wee, S., Coffman, M., LaCroix, S. (2019). Data on U.S. State-Level Electric Vehicle Policies, 2010-2015. Data in Brief, 23: 103658. https://doi.org/10.1016/j.dib.2019.01.006.

Wee, S., Coffman, M., LaCroix, S. (2018). Do Electric Vehicle Incentives Matter? Evidence from 50 U.S. States.Research Policy, 47(9). https://doi.org/10.1016/j.respol.2018.05.003.

Coffman, M., Bernstein, P., Wee, S. (2016). Integrating Electric Vehicles and Residential Solar PV. Transport Policy, 53: 30-38. https://doi.org/10.1016/j.tranpol.2016.08.008.

Coffman, M., Bernstein, P., Wee, S. (2016). Electric Vehicles Revisited: A Review of Factors that Affect Adoption. Transport Reviews, 37:1, 79-93. https://doi.org/10.1080/01441647.2016.1217282.

Coffman, M., Bernstein, P., Wee, S., and Schafer, C. (2016).  Economic and GHG Impacts of Natural Gas for Hawai‘i.Environmental Economics and Policy Studies, 19: 3, 519-536. https://doi.org/10.1007/s10018-016-0157-2.

Coffman, M., Wee, S., Bonham, C., and Salim, G. (2015).  A Policy Analysis of Hawai‘i’s Solar Tax Credit Incentive.Renewable Energy, 85: 2036-1043. https://doi.org/10.1016/j.renene.2015.07.061.

Mochizuki, J., Coffman, M., and Yanagida, J. (2015). Market, Welfare and Land-Use Implications of Lignocellulosic Bioethanol in Hawai‘i. Renewable Energy, 76: 102-114. https://doi.org/10.1016/j.renene.2014.10.071.

Coffman, M., and Bernstein, P. (2014).  Linking Hawai‘i’s Islands with Wind Energy. Annals of Regional Science, 54: 1-21. https://doi.org/10.1007/s00168-014-0644-y.

Coffman, M. (2014).  Energy, The Value of Hawai‘i 2: Ancestral Roots, Oceanic Visions, Eds. Yamashiro, Aiko; Goodyear-Kaopua, Noelani. University of Hawai‘i Press.

Coffman, M., Griffin, J., and Bernstein, P. (2012).  An Assessment of Greenhouse Gas Emissions-Weighted Clean Energy Standards. Energy Policy, 45: 122-132. https://doi.org/10.1016/j.enpol.2012.01.068.

Coffman, M. (2010).  Oil Price Shocks and Hawai‘i’s Economy: An Analysis of the Oil-Price Macroeconomy Relationship. Annals of Regional Science, 44(3): 599-620. https://doi.org/10.1007/s00168-008-0271-6.