Hawai‘i and Pacific Islands

Climate change—especially sea level rise, altered rainfall patterns, and rising ocean and air temperatures—impairs access to clean water and healthy food, undermines human health, threatens cultural resources and the built environment, exacerbates inequities, and disrupts economic activity and diverse ecosystems in Hawaiʻi and the US-Affiliated Pacific Islands. Adaptation efforts that build upon community strengths and center local and Indigenous Knowledge systems improve resilience.

Key Points:

The rate of increase in regional sea surface temperatures has exceeded global rates, while ocean acidification has reached levels not seen over the past 30 years. Sea level rise is compromising critical infrastructure and threatens to displace populations on low-lying atolls, forcing migration and disrupting social relationships.

Climate change poses risks to the region’s rich biodiversity, including many threatened and endangered species, that supports functioning ecosystems and cultural practices.

Access to clean, fresh water and healthy food is expected to be increasingly impaired by climate change. On low-lying atolls, sea level rise has caused saltwater contamination of fresh water.

Degradation of coral reefs due to a rise in sea surface temperatures could incur coastal damages costing approximately $1.2 billion (in 2022 dollars) annually to the economies of Hawaiʻi and the US Pacific territories. Warming waters, acidification, and deoxygenation redistribute open-ocean fish stocks, and fisheries catch within regional EEZs is projected to decline by up to 40% by 2050 relative to the early 2000s under a very high scenario.

U.S.-Affiliated Pacific Islands mangroves and seagrasses are among the world’s most productive blue carbon ecosystems, storing over 30% of total island carbon despite their small area.

Adaptation efforts that build upon community strengths and center local and Indigenous Knowledge systems improve resilience.

View the Hawai‘i and Pacific Islands chapter of the Fifth National Climate Assessment >>

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Previous Hawai‘i and Pacific Islands content developed by the Toolkit team

Key Points from the report "Climate Change and Pacific Islands: Indicators and Impacts."

Warmer and drier conditions projected for the future mean that freshwater supplies will decrease on some Pacific Islands. Atolls and low-lying islands are especially vulnerable to freshwater shortages due to their small size and limited resources.
Rising sea levels, exacerbated by storms, will increase coastal flooding and erosion, damaging coastal ecosystems and infrastructure and affecting low-lying aquifers, agriculture, tourism, and other industries.
Rising temperatures and changing patterns of rainfall will stress native Pacific Island plant and animal populations and species. Combined with a range of non-climate stressors, these conditions increase the risk of local extinction for some species.
Higher ocean temperatures will increase coral bleaching, leading to changes in coral species composition, coral disease, coral death, and habitat loss. Increasing ocean acidification will have negative consequences for the entire marine ecosystem. Observed patterns in coastal and ocean fisheries will be altered due to changes in ocean circulation.
Mounting threats to food and water security, infrastructure, and public health and safety will lead to human migration from low islands to high islands and continental sites. Climate-related threats also make it difficult for indigenous communities to sustain their connection with defined places and their unique set of customs, beliefs, and languages.

The Pacific Islands region is spread across millions of square miles of the Pacific Ocean, encompassing more than 2,000 islands with about 1.9 million inhabitants, representing numerous languages and cultures. These islands attract millions of tourists every year and support a large U.S. military presence. The region includes diverse terrestrial and marine ecosystems, including pristine habitat that supports tremendous biodiversity.

This map show the locations of Hawai‘i and U.S.-Affiliated Pacific Islands, and highlights U.S. Exclusive Economic Zones and Marine National Monuments (MNM).

Across the Pacific Islands region, weather and climate are highly variable. Climate variability—best represented by the El Niño-Southern Oscillation (ENSO)—has a large influence on year-to-year changes in rainfall, sea level, and other climate variables across the islands. Several distinct multi-year patterns of shifting atmospheric pressures, wind patterns, and ocean temperatures can make it difficult to distinguish shorter-term climate variability from longer-term trends.

Despite the prevalence of short-term variations, several long-term trends have emerged from observations over the last century. Observed changes include an increase in average surface air temperature (most pronounced at high altitudes in Hawai‘i), a decrease in rainfall across much of the region, decreased groundwater storage in Hawai’i, rising mean sea level (especially in the western Pacific), more frequent and prolonged drought, changes in habitat and species distributions, rising ocean heat content, and changing ocean chemistry.

Adaptation is essential

Observed climate trends and results from global climate models make it clear that the cumulative impacts of climate change will require Pacific communities to implement some degree of climate adaptation in order to deal with new conditions. Informed and timely responses will be necessary, especially on low-lying islands and atolls, to improve communities’ resilience to the challenges posed by climate change. However, adaptive capacity across the Pacific Islands region varies with the availability of socioeconomic and institutional resources.

The Climate Resilience Toolkit offers case studies illustrating how people in the Pacific Islands are recognizing and addressing their climate threats.

Additional research, continued monitoring, a sustained assessment process, and public engagement in the development and sharing of useful information will enhance Pacific Islanders’ ability to address climate challenges. Island residents can participate in and/or learn from regional coordination efforts that facilitate data collection, analysis, and access to information: these efforts offer significant contributions for groups who are developing adaptation plans and policies. Regional communication and collaboration provides a strong foundation for ongoing efforts to build resilience in the face of challenges from a changing climate.

Featured Tools for the Steps to Resilience

① Explore Hazards

Pacific Islands Regional Climate Assessment (PIRCA)

Hawai'i and U.S. Pacific Islands Region Climate Impacts and Outlook

Sea Level Rise Hawaii

② Assess Vulnerability & Risks

Rainfall Atlas of Hawaiʻi

Hawai'i Flood Hazard Assessment Tool

③ Investigate Options

Sea-Level Rise and Coastal Land Use in Hawaii: A Policy Tool Kit for State and Local Governments

Hawaii Coastal Erosion Management Plan (PDF report)

Hawai'i and Pacific Islands Case Studies

④ Prioritize & Plan

Hawai'i Coastal Erosion Website

Hawai'i Social Network Analysis

A Blueprint for Action: Water Security for an Uncertain Future 2016–2018 (PDF report)

Learn more

To learn more about the impacts of climate change and variability in Hawai'i and the Pacific Islands, and access Case Studies and tools for the region, visit these pages: