Federal Coordinating Lead Author:
David Helweg, DOI Pacific Islands Climate Adaptation Science Center
Chapter Lead:
Victoria Keener, East-West Center
Chapter Authors:
Susan Asam, ICF
Seema Balwani, National Oceanic and Atmospheric Administration
Maxine Burkett, University of Hawai‘i at Mānoa
Charles Fletcher, University of Hawai‘i at Mānoa
Thomas Giambelluca, University of Hawai‘i at Mānoa
Zena Grecni, East-West Center
Malia Nobrega-Olivera, University of Hawai‘i at Mānoa
Jeffrey Polovina, NOAA Pacific Islands Fisheries Science Center
Gordon Tribble, USGS Pacific Island Ecosystems Research Center
Review Editor:
Jo-Ann Leong, Hawai‘i Institute of Marine Biology
Technical Contributors:
Malia Akutagawa, University of Hawaiʻi at Mānoa, Hawaiʻinuiākea School of Hawaiian Knowledge, Kamakakūokalani Center for Hawaiian Studies, William S. Richardson School of Law, Ka Huli Ao Center for Excellence in Native Hawaiian Law
Rosie Alegado, University of Hawaiʻi at Mānoa, Department of Oceanography, UH Sea Grant
Tiffany Anderson, University of Hawai‘i at Mānoa, Geology and Geophysics
Patrick Barnard, U.S. Geological Survey–Santa Cruz
Rusty Brainard, NOAA Pacific Islands Fisheries Science Center
Laura Brewington, East-West Center, Pacific RISA
Jeff Burgett, Pacific Islands Climate Change Cooperative
Rashed Chowdhury, NOAA Pacific ENSO Applications Climate Center
Makena Coffman, University of Hawai‘i at Mānoa, Urban and Regional Planning
Chris Conger, Sea Engineering, Inc.
Kitty Courtney, Tetra Tech, Inc.
Stanton Enomoto, Pacific Islands Climate Change Cooperative
Patricia Fifita, University of Hawai‘i, Pacific Islands Climate Change Cooperative
Lucas Fortini, USGS Pacific Island Ecosystems Research Center
Abby Frazier, USDA Forest Service
Kathleen Stearns Friday, USDA Forest Service, Institute of Pacific Islands Forestry
Neal Fujii, State of Hawai‘i Commission on Water Resource Management
Ruth Gates, University of Hawai‘i at Mānoa, School of Ocean and Earth Science and Technology
Christian Giardina, USDA Forest Service, Institute of Pacific Islands Forestry
Scott Glenn, State of Hawai‘i Department of Health, Office of Environmental Quality Control
Matt Gonser, University of Hawai‘i Sea Grant
Jamie Gove, NOAA Pacific Islands Fisheries Science Center
Robbie Greene, CNMI Bureau of Environmental and Coastal Quality
Shellie Habel, University of Hawai‘i at Mānoa, School of Ocean and Earth Science and Technology
Justin Hospital, NOAA Pacific Islands Fisheries Science Center
Darcy Hu, National Park Service
Jim Jacobi, U.S. Geological Survey
Krista Jaspers, East-West Center, Pacific RISA
Todd Jones, NOAA Pacific Islands Fisheries Science Center
Charles Ka‘ai‘ai, Western Pacific Regional Fishery Management Council
Lauren Kapono, NOAA Papahānaumokuākea Marine National Monument
Hiʻilei Kawelo, Paepae O Heʻeia
Benton Keali‘i Pang, U.S. Fish and Wildlife Service
Karl Kim, University of Hawai‘i, National Disaster Preparedness Training Center
Jeremy Kimura, State of Hawai‘i Commission on Water Resource Management
Romina King, University of Guam and Pacific Islands Climate Adaptation Science Center
Randy Kosaki, National Oceanic and Atmospheric Administration
Michael Kruk, ERT, Inc.
Mark Lander, University of Guam, Water and Environmental Research Institute
Leah Laramee, State of Hawaiʻi Department of Land and Natural Resources
Noelani Lee, Ka Honua Momona
Sam Lemmo, State of Hawai‘i Department of Land and Natural Resources, Interagency Climate Adaptation Committee
Rhonda Loh, Hawaiʻi Volcanoes National Park
Richard MacKenzie, USDA Forest Service, Institute of Pacific Islands Forestry
John Marra, National Oceanic and Atmospheric Administration
Xavier Matsutaro, Republic of Palau, Office of Climate Change
Marie McKenzie, Pacific Islands Climate Change Cooperative
Mark Merrifield, University of Hawai‘i at Mānoa
Wendy Miles, Pacific Islands Climate Change Cooperative
Lenore Ohye, State of Hawai‘i Commission on Water Resource Management
Kirsten Oleson, University of Hawai‘i at Mānoa
Tom Oliver, University of Hawaiʻi at Mānoa, Joint Institute for Marine and Atmospheric Research
Tara Owens, University of Hawai‘i Sea Grant
Jessica Podoski, U.S. Army Corps of Engineers—Fort Shafter
Dan Polhemus, U.S. Fish and Wildlife Service
Kalani Quiocho, NOAA Papahānaumokuākea Marine National Monument
Robert Richmond, University of Hawaiʻi, Kewalo Marine Lab
Joby Rohrer, O‘ahu Army Natural Resources
Fatima Sauafea-Le‘au, National Oceanic and Atmospheric Administration—American Sāmoa
Afsheen Siddiqi, State of Hawaiʻi Department of Land and Natural Resources
Irene Sprecher, State of Hawaiʻi, Department of Land and Natural Resources
Joshua Stanbro, City and County of Honolulu Office of Climate Change, Sustainability and Resiliency
Mark Stege, The Nature Conservancy—Majuro
Curt Storlazzi, U.S. Geological Survey–Santa Cruz
William V. Sweet, National Oceanic and Atmospheric Administration
Kelley Tagarino, University of Hawai‘i Sea Grant
Jean Tanimoto, National Oceanic and Atmospheric Administration
Bill Thomas, NOAA Office for Coastal Management
Phil Thompson, University of Hawai‘i at Mānoa, Oceanography
Mililani Trask, Indigenous Consultants LLC
Barry Usagawa, Honolulu Board of Water Supply
Kees van der Geest, United Nations University, Institute for Environment and Human Security
Adam Vorsino, U.S. Fish & Wildlife Service
Richard Wallsgrove, Blue Planet Foundation
Matt Widlansky, University of Hawai‘i, Sea Level Center
Phoebe Woodworth-Jefcoats, NOAA Pacific Islands Fisheries Science Center
Stephanie Yelenik, USGS Pacific Island Ecosystems Research Center
USGCRP Coordinators:
Allyza Lustig, Program Coordinator
Fredric Lipschultz, Senior Scientist and Regional Coordinator

Hawai‘i and U.S.-Affiliated Pacific Islands

The U.S. Pacific Islands are culturally and environmentally diverse, treasured by the 1.9 million people who call them home. Pacific islands are particularly vulnerable to climate change impacts due to their exposure and isolation, small size, low elevation (in the case of atolls), and concentration of infrastructure and economy along the coasts.

A prevalent cause of year-to-year changes in climate patterns around the globe1 and in the Pacific Islands region2 is the El Niño–Southern Oscillation (ENSO). The El Niño and La Niña phases of ENSO can dramatically affect precipitation, air and ocean temperature, sea surface height, storminess, wave size, and trade winds. It is unknown exactly how the timing and intensity of ENSO will continue to change in the coming decades, but recent climate model results suggest a doubling in frequency of both El Niño and La Niña extremes in this century as compared to the 20th century under scenarios with more warming, including the higher scenario (RCP8.5).3,4

On islands, all natural sources of freshwater come from rainfall received within their limited land areas. Severe droughts are common, making water shortage one of the most important climate-related risks in the region.5 As temperature continues to rise and cloud cover decreases in some areas, evaporation is expected to increase, causing both reduced water supply and higher water demand. Streamflow in Hawai‘i has declined over approximately the past 100 years, consistent with observed decreases in rainfall.6

The impacts of sea level rise in the Pacific include coastal erosion,7,8 episodic flooding,9,10 permanent inundation,11 heightened exposure to marine hazards,12 and saltwater intrusion to surface water and groundwater systems.13,14 Sea level rise will disproportionately affect the tropical Pacific15 and potentially exceed the global average.16,17

Invasive species, landscape change, habitat alteration, and reduced resilience have resulted in extinctions and diminished ecosystem function. Inundation of atolls in the coming decades is projected to impact existing on-island ecosystems.18 Wildlife that relies on coastal habitats will likely also be severely impacted. In Hawaiʻi, coral reefs contribute an estimated $477 million to the local economy every year.19 Under projected warming of approximately 0.5°F per decade, all nearshore coral reefs in the Hawai‘i and Pacific Islands region will experience annual bleaching before 2050. An ecosystem-based approach to international management of open ocean fisheries in the Pacific that incorporates climate-informed catch limits is expected to produce more realistic future harvest levels and enhance ecosystem resilience.20

Indigenous communities of the Pacific derive their sense of identity from the islands. Emerging issues for Indigenous communities of the Pacific include the resilience of marine-managed areas and climate-induced human migration from their traditional lands. The rich body of traditional knowledge is place-based and localized21 and is useful in adaptation planning because it builds on intergenerational sharing of observations.22 Documenting the kinds of governance structures or decision-making hierarchies created for management of these lands and waters is also important as a learning tool that can be shared with other island communities.

Across the region, groups are coming together to minimize damage and disruption from coastal flooding and inundation as well as other climate-related impacts. Social cohesion is already strong in many communities, making it possible to work together to take action. Early intervention can lower economic, environmental, social, and cultural costs and reduce or prevent conflict and displacement from ancestral land and resources.

   

Climate Indicators and Impacts

Monitoring regional indicator variables in the atmosphere, land, and ocean allows for tracking climate variability and change. (top) Observed changes in key climate indicators such as carbon dioxide concentration, sea surface temperatures, and species distributions in Hawai‘i and the U.S.-Affiliated Pacific Islands result in (bottom) impacts to multiple sectors and communities, including built infrastructure, natural ecosystems, and human health. Connecting changes in climate indicators to how impacts are experienced is crucial in understanding and adapting to risks across different sectors. From Figure 27.2 (Source: adapted from Keener et al. 2012).23
   

Projected Onset of Annual Severe Coral Reef Bleaching

The figure shows the years when severe coral bleaching is projected to occur annually in the Hawaiʻi and U.S.-Affiliated Pacific Islands under a higher scenario (RCP8.5). Darker colors indicate earlier projected onset of coral bleaching. Under projected warming of approximately 0.5°F per decade, all nearshore coral reefs in the region will experience annual bleaching before 2050. From Figure 27.10 (Source: NOAA).

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