Hawai‘i and the US-Affiliated Pacific Islands

The Pacific Islands region is vast and diverse.  The region of focus for PIRCA includes the Hawaiian archipelago and the US-Affiliated Pacific Islands (USAPI), encompassing almost 2,000 islands and millions of square miles of ocean. The State of Hawai‘i, the US’s fourth smallest state, has the largest land area in the region. Despite the small size of most Pacific Islands, the combined exclusive economic zones (EEZ) of the region’s islands encompass an area four times the size of contiguous United States, making this region of great importance to the nation as a whole.

The islands support about 1.9 million people, representing numerous languages and cultures. Marine and land-based ecosystems in the Pacific Islands region are home to some of the most pristine habitat in the world and possess tremendous biodiversity. The islands attract millions of people as tourists every year and support a large US military presence.

The weather and climate across the region is characterized by its high natural variability. One example is El Niño-Southern Oscillation (ENSO), a pattern that has a large influence on year-to-year variability in rainfall, sea level, and other climate variables.

The PIRCA examines climate change indicators, impacts, and adaptive capacity in three sub-regions of the Pacific Islands:

  1. the Western North Pacific, including the Commonwealth of the Northern Mariana Islands, Guam, the Republic of Palau, the Federated States of Micronesia, and the Republic of the Marshall Islands
  2. the Central North Pacific, including Hawai‘i and the Northwest Hawaiian Islands
  3. the Central South Pacific, where American Samoa is located.

Climate Change in the Pacific Islands

The Pacific Islands region is experiencing climate change. Key indicators of the changing climate include rising carbon dioxide in the atmosphere, rising air and sea temperatures, rising sea levels and upper-ocean heat content, changing ocean chemistry and increasing ocean acidity, changing rainfall patterns, decreasing base flow in streams, changing wind and wave patterns, changing extremes, and changing habitats and species distributions.

Currently, the most vulnerable areas include low islands (atoll islands and other islands that rise only a few feet above present sea level), nearshore and coastal areas, and coral reefs. High-elevation ecosystems are also vulnerable. The climatic changes are affecting every aspect of life. Freshwater supplies for natural systems, as well as communities and businesses, are at risk. Food security is threatened through impacts on both agriculture and fisheries. The built environment is also at risk from coastal flooding and erosion as sea levels incrementally increase. Loss of habitat for endangered species such as monk seals, sea turtles, and Laysan ducks is expected along with increased coral bleaching episodes, expansion of avian malaria to higher elevations, and changes in the distribution and survival of the areas’ marine biodiversity. Over the coming decades, impacts are expected to become more widespread and more severe.