Prepared for the 2013 National Climate Assessment and a landmark study in terms of its breadth and depth of coverage, Climate Change and the Pacific Islands was developed by the Pacific Islands Regional Climate Assessment, a collaborative effort engaging federal, state, and local government agencies, non-government organizations, academician, businesses, and community groups to inform and prioritize their activities in the face of a changing climate. The book assesses the state of knowledge about climate change indicators, impacts, and adaptive capacity of the Hawaiian archipelago and the US-Affiliated Pacific Islands. The book provides the basis for understanding the key observations and impacts from climate change in the region, including the rise in surface air and sea-surface temperatures, along with sea levels, and the changes in ocean chemistry, rainfall amount and distribution, weather extremes, and widespread ecosystem changes. Rich in science and case studies, it examines the latest climate change impacts, scenarios, vulnerabilities, and adaptive capacity and offers decision makers and stakeholders a substantial basis from which to make informed choices that will affect the well-being of the region’s inhabitants in the decades to come.
About the Author
Dr. Victoria Keener is a Research Fellow at the East-West Center in Honolulu, Hawaìi, and the Program Manager of the Pacific RISA. Dr. John Marra is the NOAA Climate Services Director for the Pacific Region and the Director of the Pacific Climate Information System (PaCIS). Dr. Melissa Finucane is a Senior Fellow at the East West Center in Honolulu, Hawaii, and a PI of the Pacific RISA program. Deanna Spooner is the Coordinator of the Pacific Islands Climate Change Cooperative (PICCC). Margaret Smith was the PIRCA report coordinator, and a Physical Sciences Librarian at New York University.
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Climate Change and Pacific Islands
Indicators and Impacts - Report for the 2012 Pacific Islands Regional Climate Assessment (PIRCA)
By Victoria W. Keener, John J. Marra, Melissa L. Finucane, Deanna Spooner, Margaret H. Smith
ISLAND PRESSCopyright © 2012 The Pacific Islands Regional Climate Assessment (PIRCA)
All rights reserved.
Pacific Islands Region Overview
The Pacific Islands region includes the Hawaiian archipelago and the US-Affiliated Pacific Islands (USAPI). More than 2,000 islands are distributed across millions of square miles of the Pacific Ocean. The islands are isolated, with hundreds of miles of ocean between individual islands and thousands of miles between island chains. The largest aggregate of land is the State of Hawai'i, with 6,423 square miles (the fourth smallest state in the US). The islands are diverse in terms of geography, climate, ecology, and culture. The ocean and its resources play a vital role in the lives and livelihoods of the peoples of the Pacific Islands region. The combined exclusive economic zones (EEZ) of the region's islands encompass more than one-half of the entire EEZ of the US, making this region of great importance not just to Pacific Islanders, but to the US as a whole. The region is home to some of the most pristine habitat in the world and possesses tremendous biodiversity; thus, it is of immeasurable value to all people on the planet.
In this report, the islands in the region are grouped into three sub-regions (Figure 1-1), with affinities in terms of geography, climate, ecology, and sociology.
Central North Pacific (CNP) – This area includes the State of Hawai'i and the Northwestern Hawaiian Islands (Papahanaumokuakea). It represents the northern bounds of Polynesia.
Western North Pacific (WNP) – This area includes the Mariana, Caroline, and Marshall island chains: Guam; Commonwealth of the Northern Mariana Islands (CNMI); Republic of Palau (RP); Federated States of Micronesia (FSM, including the states of Chuuk, Kosrae, Pohnpei, and Yap); and Republic of the Marshall Islands (RMI). This area is also referred to as Micronesia.
Central South Pacific (CSP) – This area includes American Samoa, but consideration is given to the South Pacific in general.
Pacific Island geology and landscape
The islands of the region vary widely in terms of geologic origin. They include volcanic islands, atolls, limestone islands, and islands of mixed geologic type. The highest volcanic islands reach more than 13,000 feet, while some of the atoll islands peak at only a few feet above present sea level. The distinction between "high" islands and "low" atoll islands is essential to explain the different climates on islands and the many specialized terrestrial and marine ecosystems that have evolved, as well as the forms of human communities they currently support (Figure 1-2).
The terrain of high islands is characterized by abrupt elevation changes (mountains, sheer cliffs, steep ridges and valleys), with the altitude and size of these features varying according to the age of the island. On high islands, orographic rainfall (i.e., rain associated with or induced by the presence of mountains) can cause the island to receive much higher rainfall all than the surrounding ocean and is responsible for large differences between leeward and windward rainfall. The landscape on high islands is conducive to the formation and persistence of freshwater streams and the development of soils that can support large and diverse plant and animal populations. In contrast, the low atollislands are small and flat. They are not tall enough to generate orographic rain, and thus the amount of rainfall on low islands is close to that for the surrounding ocean. The atolls generally lack the freshwater and fertile soils that are characteristic of volcanic islands and have limited terrestrial resources. Low islands are especially prone to drought, but their varied coral reef, mangrove, and lagoon environments support rich marine ecosystems.
Because high islands have more land and freshwater resources than low islands do, they have more long-term options for responding to changes in sea level, rainfall, and other climate variables. The amount of land on volcanic islands that is flat enough for large-scale settlement, development, and agriculture is limited, however, resulting in high concentrations of population, infrastructure, and commercial development in low-lying coastal areas. Thus, while communities on high islands and low islands have somewhat similar short-term challenges associated with climate change, they have different degrees of flexibility in how they can adapt.
Pacific Island peoples, governments, and economies
The Pacific Islands region includes demographically, culturally, and economically diverse communities. The first settlers of Micronesia traveled from the Philippines and Indonesia around 4,000 years ago to settle the islands of the Republic of Palau, the Mariana archipelago, and possibly Yap. A second wave of later settlers traveled approximately 2,000 years ago from southeast Melanesia, possibly the Solomon Islands, north past Kiribati, settling the Marshall Islands and then moving west through the Caroline archipelago until they met the earlier settlers in the area of western Chuuk and Yap (Rainbird, 2004). The settlement of the Polynesian region began with the early Austronesian ancestors from Taiwan approximately 5,000 years ago (Gray et al., 2009). Over thousands of years, these early settlers traveled west through Samoa, Fiji, and Tonga in western Polynesia before reaching the Cook, Society, Tuamoto, and Marquesas archipelagos in eastern Polynesia. The first permanent settlers of Hawai'i sailed north from this area, reaching the Hawaiian Islands approximately 1,200 years ago (Graves & Addison, 1995; Vitousek et al., 2004).
Contact with Europeans began with Magellan's fleet, which landed at Guam in 1521, and continued for the following four centuries under multiple colonial powers. Today, islands with ties to the US are home to nearly 1.9 million people, with most (nearly 1.4 million) living in Hawai'i. The majority of the island populations are composed of diverse indigenous Pacific Islander communities, intermingled with immigrants mostly from Asia, Europe, North America, Australia, and New Zealand. At least 20 languages are spoken in the region. On many islands, a large proportion of the population is rural. As rural communities often depend on agriculture and other environmentally sensitive practices, they are extremely vulnerable to weather and climate conditions.
The islands have varied histories of governance. A series of foreign countries have, at different times, governed most island chains or individual islands. Contemporary social systems throughout the region vary widely, with traditional Micronesian or Polynesian rules and institutions mixed with those adopted from colonizing countries. In Hawai'i and Guam, cash economies are highly developed, relatively few people rely on subsistence agriculture or fishing, and western legal systems dominate. In American Samoa and throughout Micronesia, traditional cultural systems govern behavior and traditional political structures are in place. Tribal systems led by chiefs have a large influence on decision making in the RMI, the FSM, and American Samoa (Petersen, 2009).
Pacific Island populations share a cultural value that links society and the environment. Resource management and conservation are essential for healthy, stable communities on islands with limited resources because overexploitation could damage or permanently destroy resources. A key value for survival in Hawai'i, for instance, is malama 'aina, which means caring for the land (Kawaharada, 2011). In general, Pacific Island cultures recognize the value and relevance of their cultural heritage and systems of traditional knowledge and customary law developed within their social, cultural, and natural contexts (e.g., Gegeo & Watson-Gegeo, 2001). At the same time, contemporary island communities reflect diverse ancestries that, over time, have blended to create new cultural values. There is an emphasis on long-term connection with lands and resources, with multigenerational attachment to places (Gegeo, 2001; Teddy, Nikora, & Guerin, 2008). Climate change threatens the physical, biological, and human elements necessary for Pacific Island cultures to sustain their co-existence and evolving relationship with a defined place and to maintain their unique set of customs, beliefs, language, traditional knowledge, objects, and built environment. This threat is due in part to the familial and divine relationships certain Pacific Island cultures have with the natural world and the implications of severed kinship ties when places, species, and practices are lost (e.g., Lili'uokalani, 1997).
Economic indicators show a wide range within the region (Table 1-1). Tourism figures prominently in the GDP of most island jurisdictions. Hawai'i, for instance, welcomed almost 7 million visitors to the state in 2011, generating $12.6 billion in revenue (Hawai'i Tourism Authority, 2011). A large US military presence means that the defense sector is also an important source of income. Climate change threatens the ecosystems (such as forests, streams, coral reefs, and open ocean) that communities rely on for sustenance and revenue. Geographic remoteness means that the cost of transport has a profound influence on island economies.
The isolation of the communities of the region, from one another and from the rest of the world, has led to the development of technological and cultural strategies for responding to events such as typhoons and large inter-annual variability in rainfall. Historically, settlement patterns, crop diversity, food storage and preservation techniques, and strategies for intercommunity cooperation have evolved in different ways to cope with local conditions on each island (Barnett & Campbell, 2010). More recently, the recurrence of drought in the FSM has prompted systems of rationing and strategies for importing water (UN Office for the Coordination of Humanitarian Affairs, 1998).
Although isolation has proved helpful in the development of adaptations that are highly specific to local needs, it has limited the gathering and exchange of regional information that could support and enhance local adaptation strategies. Scientific study is inhibited by the labor and costs required to maintain climate monitoring systems in such remote locations. At the national and global levels, decisions on adaptation strategies are made without good information from the region. Conversely, distribution of national and global scientific and policy information around the region must be translated into multiple languages.
Several region-wide initiatives aim to foster communication and information sharing on climate-related topics. These include the Pacific Climate Information System (http://www.pacificcis.org/), Pacific Regional Integrated Sciences and Assessments program (http://www.pacificrisa.org/), Pacific Islands Climate Change Cooperative (http://www.piccc.net/), Pacific Risk Management O'hana (http://collaborate.csc.noaa.gov/PRiMO/),and the Secretariat of the Pacific Regional Environment Programme's Pacific Climate Change Roundtable and Pacific Adaptation to Climate Change project (http://www.sprep.org/pacc- home). The Micronesia Challenge represents a similar effort, with a focus on the Western North Pacific sub-region (http://www.micronesiachallenge.org/).
Pacific Island ecosystems
The region is home to unique natural communities of global significance. It is characterized by a variety of linked and interacting ecosystems that range from alpine shrublands to wet forests, mountain streams to mangroves, and coral reefs to deep-sea trenches that extend across the world's largest ocean. The same ocean currents and winds that guided human expansion and colonization of the islands also served to transport animals, plants, and microorganisms across great distances. The isolated nature of the islands has led to ecosystems that are unique, diverse, and relatively pristine, with extremely large numbers of endemic species (Pratt & Gon, 1998; Sadler, 1999; Ziegler, 2002). Yet the region's rich biodiversity is fragile. In addition to climate change, human-related impacts from agricultural and infrastructure development mean that more than 400 island species are listed under the Endangered Species Act. Many of these species are found in a network of protected areas, including 22 National Wildlife Refuges, 11 National Park units, 4 Marine National Monuments, 2 National Marine Sanctuaries, and state, territorial, local, and private conservation areas. Sustaining the health of ocean and coastal ecosystems and their accompanying resources is vital to island life.
Weather and climate
Because of its proximity to the Equator, the Pacific Islands region experiences relatively small seasonal variations in air temperature. In contrast, rainfall varies widely by season and location. The islands of the region all have distinct wet and dry seasons that loosely correspond to winter and summer months. However, the timing, duration, and intensity of these seasons, like the weather and climate in general, vary due to the combinations of atmospheric and ocean circulation patterns that are unique to each sub-region.
The dominant "centers of action" with respect to atmospheric circulation in the Central North Pacific are the North Pacific High (NPH), the Aleutian Low (AL), and the Intertropical Convergence Zone (ITCZ) (see Appendix A). In the Western North Pacific, important elements include the East Asian and Western Pacific monsoon system. In the Central South Pacific, in particular the area around American Samoa, the South Pacific Convergence Zone (SPCZ) is highly influential. The oceanic circulation of the region is dominated by the westward-flowing tropical branches of the North and South Pacific Gyre systems, namely the North and South Equatorial Currents (NEC, SEC) and, to a lesser degree, the eastward-flowing North Equatorial Counter Current (NECC) and the cold Equatorial Undercurrent (EUC) that flows eastward beneath the SEC at the equator and feeds the equatorial upwelling within the eastern tropical Pacific. The role of the ocean in controlling weather and climate cannot be underestimated. Sea-surface temperature, for example, affects tropical cyclone formation. The ocean (and the coupled atmospheric as well as chemical and biological) system redistributes heat from the tropics to the poles (as well as moisture, dissolved oxygen, nutrients, and so forth). It also serves as a global sink for heat and carbon dioxide.
Central North Pacific
Weather and climate in the Central North Pacific sub-region (CNP) are strongly influenced by the NPH and associated northeast trade winds, which blow about 75% of the year. During the winter in the northern hemisphere, the NPH is located closer to the equator and on average is smaller, weaker, or even absent (Figure 1-3). The winter is also when the AL is large, most intense, and located farther south, with the associated prevailing winds from the west reaching as far south as 28°N. It is during this time that extra-tropical cyclones regularly spin-up off the AL and drop into the prevailing west winds. These storms lead to the high waves that reach the northern shores of the Hawaiian Islands. During the northern hemisphere summer, the AL is located farther north and is impermanent or nonexistent, whereas the NPH reaches its peak size and northernmost position. Trade winds, blowing from the east, extend correspondingly, on average to 35°N. The frequency of rainfall associated with the trade winds also increases (NOAA Pacific Storms Climatology Products, n.d.).
Western North Pacific
Weather and climate in the Western North Pacific sub-region (WNP) are shaped by its proximity to the NPH, associated trade winds, and the monsoon trough, a local manifestation of the ITCZ, a zone of converging winds and relatively high rainfall. The position of the monsoon trough varies seasonally. From May to October, it moves through the sub-region, bringing each island its rainy season. The trade winds are stronger and last longer in the northern and eastern parts of the sub-region (closest to their origin in the NPH). They can also generate high surf (NOAA Pacific Storms Climatology Products, n.d.). The trade winds are more persistent during the winter months and less persistent during the summer months when the monsoon trough expands, creating strong winds from the southwest (Kodama & Businger, 1998). The trade winds are most persistent in RP and the southwestern parts of the sub-region, episodic on Guam, and rarely felt in RMI to the northeast (Bridgman & Oliver, 2006; NOAA Pacific Storms Climatology Products, n.d.). The monsoon trough activity makes the WNP the most active tropical cyclone basin, with an annual average of approximately 26 cyclones reaching tropical storm strength or greater (Knapp et al., 2010).
Central South Pacific
The weather and climate of the Central South Pacific sub-region (CSP) are affected by the South Pacific Convergence Zone (SPCZ). Like the ITCZ, the SPCZ is a zone of converging winds and relatively high rainfall. Trade winds dominate from May to October, although the winds originate from subtropical high-pressure areas in the southern hemisphere instead of the NPH. Rainfall varies widely by season: approximately 75% of annual rainfall all occurs from November to April, when the SPCZ is located about halfway between Western Samoa and Fiji. During the dry season, the SPCZ moves out of the area and often becomes weak or inactive (Australian Bureau of Meteorology & CSIRO, 2011). Heavy rainfall in this sub-region is primarily associated with tropical cyclones.
Excerpted from Climate Change and Pacific Islands by Victoria W. Keener, John J. Marra, Melissa L. Finucane, Deanna Spooner, Margaret H. Smith. Copyright © 2012 The Pacific Islands Regional Climate Assessment (PIRCA). Excerpted by permission of ISLAND PRESS.
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Table of Contents
About this Report Executive Summary Hawaii Governor's Letter List of Figures and Tables List of Abbreviations Chapter 1: Pacific Islands Region Overview -Region profile -Pacific Island geology and landscape -Pacific Island peoples, governments, and economies -Pacific Island ecosystems -Box 1-1: Marine national monuments in the Pacific Islands region -Box 1-2: Ecosystems of the Pacific Islands region -Weather and climate -Inter-annual and interdecadal variability-Box 1-3: Distinguishing climate variability from climate change in the Pacific-Observations and monitoring -Box 1-4: The value of high-quality observations and monitoring: Mauna Loa Observatory, HaleNet, and Station ALOHA -Models and projections -Indicators of a changing climate in the Pacific Islands region -Impacts of a changing climate in the Pacific Islands region -Adaptive capacities-Box 1-5: Climate change will force human migration from the Pacific Islands -Advancing knowledge -Conclusion -Box 1-6: Assessing information needs for managing O'ahu's freshwater resources Chapter 2. Freshwater and Drought on Pacific Islands -Freshwater hydrology overview -Historic and current trends-Box 2-1: The Hawai'i Water Code: Providing a strong basis for management and planning -Box 2-2: High-quality data and monitoring networks are threatened -Projections -Impacts and adaptation -Summary -Case Study 2-1: Managing vulnerable water resources in atoll nations -Case Study 2-2: Using climate forecasts to save money and protect human health -Case Study 2-3: Climate change likely to intensify freshwater disputes in Hawai'i Chapter 3. Sea Level and Coastal Inundation on Pacific Islands -Overview -Historic and current trends -Box 3-1: How do you measure sea level? -Extreme sea-level events -Climate projections and sea level -Impacts -Summary -Case Study 3-1: A combination of processes creates extreme water levels and contributes to flooding and erosion -Case Study 3-2: Mapping sea-level rise in Honolulu Chapter 4. Marine, Freshwater, and Terrestrial Ecosystems on Pacific Islands -Regional ecosystems overview -Historic and projected trends -Impacts to marine ecosystems -Impacts to freshwater and terrestrial ecosystems -Implications of climate change for management -Summary -Case Study 4-1: Climate change threatens Hawaiian forest birds -Case Study 4-2: Fish populations respond to climate conditions -Case Study 4-3: Pacific coral reef management in a changing climate Chapter 5. Summary and Conclusions -Advancing Knowledge -Partnerships Appendix A: Glossaries Related to Weather and Climate in the Pacific Islands Appendix B: Future Regional Climate Modeling and Projections Appendix C: Members of the PIRCA Core Team Appendix D: Members of the PIRCA Steering Committee Appendix E: Freshwater and Drought Technical Workshop Appendix F: Sea-level Rise and Coastal Inundation Technical Workshop Appendix G: Marine, Freshwater, and Terrestrial EcosystemsTechnical Workshop Appendix H: Summary of Workshop Evaluations References