American Sāmoa

Territory of American Sāmoa

American Sāmoa is part of the Samoan Islands archipelago, located in the mid-South Pacific Ocean in the heart of the region known as Polynesia. The main island, Tutuila, is the location of the capital of Pago Pago and the majority of the nation’s population. There are four other inhabited volcanic islands: Aunu’u, which is close to Tutuila; and Ofu, Olosega, and Ta’u, which are located approximately 70 miles (110 km) east of Tutuila and together make up the Manu’a Islands [12]. Two coral atolls – uninhabited Rose Atoll, which is part of a marine national monument, and inhabited Swains Atoll – are also included in the territory. The total land area of the nation is 77 sq miles (199 sq km) [8]. The volcanic islands are extremely rugged, with limited coastal plains, and only about thirty percent of the land is available for development [9]. Pago Pago harbor, located on Tutuila Island, is one of the best natural deepwater harbors in the South Pacific. Its excellent shipping capacity, as well as strategic location in the South Pacific Ocean, led to significant international interest in and presence on the island since the 19^th century, resulting in the U.S. formally occupying the islands in 1900 [7, 8].

Climate

American Sāmoa’s climate is tropical with a relatively dry season, June through August, and a wet season, January through March. The amount of rainfall can vary greatly depending on the location and from year to year [6]. For example, the rainfall averages about 125 inches a year at the airport, but Pago Pago, less than 4 miles from the airport at the head of a harbor open to the prevailing wind, receives nearly 200 inches a year [5]. Trade winds blow almost continually [6]. The prevailing winds throughout the year are easterly trades, interrupted more often in summer than winter, and sometimes associated with tropical cyclones, convergence bands, and upper-level disturbances. Heavy showers and long rainy periods can occur in any month, while typhoons are common from December to March [13]. Tropical cyclones impact the island chain with tropical storm-force winds on average once every three years [7]. In 2003, heavy rainfalls resulted in severe landslides and flooding, for which a Presidential Disaster Declaration was made [1]. Tropical Cyclone Heta in 2004 and Tropical Cyclone Olaf in 2005 resulted in disaster declarations with flooding, high surf, and high winds [2].

Human health risks, stronger cyclones, coral reef death, and coastal flooding are among the major challenges American Sāmoa will face due to climate change [1].  ENSO has demonstrated impacts on the migration and abundance of tuna in the tropical Pacific Ocean [4]. The changes in catch sizes, species composition, and other characteristics pose challenges to harvesting and processing, which can result in economic losses [3]. To cope with and adapt to these changes, there is a clear need to integrate climate information and study into fisheries research and management. American Sāmoa developed a climate change working group within the Coral Reef Advisory Group to monitor impacts of changes on coral reef ecosystems. Understanding that the natural environment contributes to their livelihood, the American Sāmoa government has formed many environmental task forces and initiatives to promote sustainable development of resources for the long-term survival of their people. For a comprehensive summary of climate trends and future projections, and how climate change is affecting American Sāmoa’s key sectors, see Climate Change in American Sāmoa: Indicators and Considerations for Key Sectors (June 2021).