Climate Change and Impacts in the Pacific

Climate change has been recognized as one of the most critical and controversial issues facing the world in the twenty-first century. It is predicted to lead to adverse and irreversible impacts on the earth and ecosystems as a whole. This chapter discusses the causes of climate change and current and potential impacts that will affect the people now and in the coming decades while providing a comprehensive account of how Pacific Island nations face challenges from climate change-related impacts. Global warming, sea-level rise, changing weather patterns and extreme events, pressure on water and food security, human health risks, and impacts on wildlife and ecosystems are considered as major impacts of climate change. Pacific Island countries register the greatest negative impacts of climate change even though they account for only 0.03% of the world’s total greenhouse gas emissions. Current and projected climate change poses a set of fundamental challenges to the local economy and livelihoods, resulting in human mobility and cross-border displacement and migration. The dispersed nature and heterogeneity of the Pacific Island countries presents special challenges for localized climate projections and adaptation strategies. Effective adaptation measures and policies to climate change impacts in the Pacific Islands should acknowledge their unique environmental and cultural characteristics.

Oceanic islands have a history of being misunderstood by outsiders, commonly marginalized in global synthesis and planning, their considerable diversity often understated. To capture and explain the diversity of islands in the Pacific, a classification is developing using elevation and lithology (rock type) as the highest level criteria. For each of the 1779 islands, defined as ocean-bounded landmasses ≥1 ha (0.01 km²) in area, data were collected on locations and shapes, areas, names, elevations and lithologies. Eight island types were identified—volcanic high islands (≥30 amsl, ≥80% igneous); volcanic low islands (<30 amsl, ≥80% igneous); limestone high islands (≥30 amsl, ≥80% calcareous); limestone low islands (<30 amsl, ≥80% calcareous); reef islands (≥80% unconsolidated sediments); composite high islands (≥30 amsl, <80% igneous, <80% calcareous); composite low islands (<30 amsl, <80% igneous, <80% calcareous); continental (≥80% continental rocks). The broad distribution of each island type in the Pacific can be explained by its geological history. In addition, this classification could be used as an objective basis for assessing island vulnerability to external stressors like climate change or pollution as well as a tool for national/regional planning.

Small island countries in the Pacific have characteristics which enhance their vulnerability and reduce their resilience to the effects of climate change, sea-level rise and extreme events. Over the past decade, a number of studies have been undertaken to improve our understanding of climate variability and change in the Pacific. This chapter provides an overview of those studies and discusses possible challenges associated with climate model projections for the small island countries in the Pacific.

This chapter details an objective method of developing an index of island susceptibility to climate change. Three separate indices are developed to estimate the potential of an island to physical change in response to likely climatic changes. These are indicative susceptibility, exposure index and geomorphic susceptibility. To develop the indicative susceptibility, four physical variables that are readily available or can be calculated from other datasets were used. These were lithology, shape of islands, maximum elevation and area. The exposure index took into account broad-scale climate and oceanic processes, such as composite water level range (ENSO and tide), average annual significant wave height and tropical cyclone frequency. The geomorphic index was a combination of the first two with relevant weightings applied. A database encompassing 15 countries and 1532 islands spread across the Pacific Ocean was developed. Analysis showed that there was a wide spread of island susceptibility, with reef islands mostly being very highly susceptible while volcanic high islands were the least susceptible. Some countries in the Pacific had all their islands in the high or very high susceptibility classes, confirming the potential risks climate change poses for them. The index has the potential to be used as a rapid appraisal tool for prioritization of adaptation measures to a changing climate.

Assessment of Pacific island vulnerability to changing climate and ocean conditions was undertaken at two scales, demonstrating a technique for vulnerability downscaling and establishing the suitability of coastal landform information to application at country or island scale. The approach acknowledges the transition of physical characteristics influencing coastal vulnerability with scale. At the whole-island scale, the geologic and morphologic structure describes likely susceptibility to change. At a more detailed scale, considering landforms comprising the coastal fringe of each island, physical characteristics describe relative coastal instability. The assessment demonstrated linkage between the two scales, with a shift from predominantly static geologic to more dynamic geomorphic data. The analyses explore a technique using remotely sensed data covering the Pacific Islands and may be applicable across a range of planning and management scales from broad, regional description of different island types to single island coasts. Although this carries potential problems of misinterpretation, it also offers opportunity for tighter definition of criteria at a country or island scale where authorities could verify the interpretations through direct field observation.

Impacts of tropical cyclones in the South Pacific Island countries are of great significance. Now with the growing threats from human-induced climate change, the need for effective disaster risk management and adaptation strategies for these island countries is more important than before. In order to implement appropriate strategies, a comprehensive understanding of South Pacific tropical cyclone activity—and how it is likely to change as a result of human-induced climate change—is essential. While a number of past studies have examined various aspects of tropical cyclone activity in the South Pacific basin, a review that consolidates those studies with new information is essential. In this chapter, we first examine tropical cyclone data quality for the South Pacific basin and then review the robustness of the relationship between South Pacific tropical cyclones and drivers of natural climate variability. Note that an understanding of the limitations of the data quality is important to determine the extent of natural climate variability and signatures—if any—of human-induced climate change on tropical cyclones. We then examine the influence of climate change on tropical cyclones using up-to-date historical observations and climate model projections.

This chapter discusses the potential impacts of climate change on coastal infrastructure in the Pacific. It also analyses the location of built infrastructure in 12 Pacific island countries with a view to determining the percentages in close proximity to the coast and so highly vulnerable to climate-related impacts. Data relating to the geographic location of all built infrastructure for 12 countries was obtained from various sources or coded directly. Buffer ranges of 0–50, 50–100, 100–200 and 200–500 m were created for each of the islands and the number of built infrastructure in each band was determined. Overall, for the 12 PICs, 57% of the built infrastructure is within 500m of the coastline. For the individual bands assessed here, 9%, 11%, 16% and 21% fall in intervals of 0–50 m, 50–100 m, 100–200 m and 200–500 m intervals, respectively. Therefore only 43% of built infrastructure is beyond 500 m of the coastline when all 12 PICs are considered together.

Pacific island countries (PICs) are highly susceptible to sea-level rise and extreme events due to their size, location, and isolated nature. Populations in PICs are generally concentrated along the coast due to transportation ease, reliance on tourism for income, and livelihoods tied to marine resources. A majority of PICs are low-lying islands and with populations distributed mainly along the coastal regions leaves them more vulnerable to climatic impacts. A detailed analysis of the exposure of populations of 12 PICs to climate change-related hazards revealed that approximately 54% of the population lives within 500 m of the coastline. In particular, Kiribati, the Marshall Islands, and Tuvalu are identified to be extremely vulnerable. They have the highest proportion of population living within close proximity of the coast, with 68.8%, 74.3%, and 64.9% of the population living within 200 m of the coast for Kiribati, the Marshall Islands, and Tuvalu, respectively. The implications of these results emphasise the importance of prioritising the populations of the small islands of the Pacific for future adaptation to coastal hazards.

Agriculture is a very important sector in Pacific Island Countries (PICs), providing a significant source of food and income for households as well as substantially contributing to national economies. Agriculture is climatically sensitive, and climate change poses major threats to the continued productivity of this critically important sector in the future. This chapter highlights the current status of agriculture in PICs, and the pathways through which climate change is already, and will continue to, impact the sector. It then presents a range of case studies that illustrate systems-oriented approaches that recognize the foundational importance of healthy soils for building agricultural resilience under a changing climate. Finally, the chapter discusses key directions for building the resilience of the agriculture sector going forward. The key priorities of agricultural plans in relation to climate change are analyzed, and key opportunities for effectively realizing these priorities are discussed. Opportunities for increasing the resilience of the agriculture sector include using integrated vulnerability and risk assessment tools, focusing on applied research and emphasizing the accessibility of research products, establishing standardized and routine monitoring and evaluation guidelines, and seeking alignment between national, regional, and international mechanisms and agreements for increasing the resilience of agriculture. Transformational adaptation of agriculture in a changing climate is critical for the livelihoods and overall resilience of Pacific Island people.

In the Pacific Island region, marine resources make vital contributions to food security, livelihoods and economic development. Climate change is expected to have profound effects on the status and distribution of coastal and oceanic habitats, the fish and invertebrates they support and, as a result, the communities and industries that depend on these resources. To prepare for and respond to these impacts—and ensure the ongoing sustainability of marine ecosystems, and the communities and industries that rely on them economically and culturally—it is necessary to understand the main impacts and identify effective adaptation actions. In particular, declines in coral reef habitats and associated coastal fisheries productivity, more eastward distribution of tuna and impacts of more intense storms and rainfall on infrastructure are expected to present the greatest challenges for Pacific communities and economies. Some species of sharks and rays, and aquaculture commodities with calcareous shells, will also be impacted by habitat degradation, ecosystem changes, increasing temperature and ocean acidification. The projected declines in coastal fish and invertebrate populations will widen the gap between fish needed by growing human populations and sustainable harvests from coastal fisheries, with shortages expected in some nations (e.g. Papua New Guinea, Solomon Islands) by 2035. There will also be a need to diversify livelihoods based on fisheries, aquaculture and tourism because some of these operations are expected to be negatively affected by climate change. In some cases, building the resilience of Pacific communities to climate change will involve reducing dependence on, or finding alternatives, vulnerable marine resources.

The 2014 Samoa UN Conference on Small Island Developing States (SIDS) reaffirmed the vulnerability of SIDS to global changes and extreme events. The effect of climate change on freshwater availability was highlighted as a major challenge. Here, we examine the diverse sources and uses of freshwater in Pacific island countries. The hydrological processes that determine freshwater availability, including ENSO events, and their historic trends across the Pacific are presented. Current challenges to water security are summarised, and the projected impacts of climate change, including sea level rise, on freshwater availability are considered. Current projections handle poorly the all-important impact of ENSO events, and because of the observed resilience of islands to sea level change, there is significant uncertainty about projections on freshwater availability apart from an increase in rainfall intensity. The best adaptation strategy appears to be overcoming the current challenges by building on the recognised strengths of island communities and investing in education and training.

The Pacific Islands region is a sensitive indicator of projected climate change in the twenty-first century. This chapter provides comprehensive information on climate change and how it impacts on biodiversity in the Pacific Island countries as it is ironically one of the most vulnerable regions in this regard. The islands of the Pacific region hold three of the 35 global biodiversity hotspots with large numbers of endemic species. The case study highlights the potential impacts of climate change on terrestrial vertebrate species found in 26 Pacific Island countries. The aim of this case study was to investigate the distribution of terrestrial vertebrate species across these countries and identify those species that were most at risk of extinction due to them being present on only one or a few islands that had previously been classified as being most susceptible to climatic change. The results show that 674 of the islands hosted at least one terrestrial vertebrate species that was either vulnerable, endangered, or critically endangered. A total of 84 terrestrial vertebrate species are endemic to this region, and many of them occupy one island only, increasing their chances of extinction.

This chapter provides an assessment of the impact of climate change and its implications for the people of 23 Pacific Island Countries and Territories. Two of these islands (Tuvalu and Tokelau) have maximum elevation of just 5 m above sea level; most of the population in the islands live on or close to the coast, and the bulk of economic activity including built infrastructure is concentrated around the shoreline. Consequently, a rise in sea level and an increase in storm surges will cause considerable economic harm to and displacement of the population. To the extent that climate change is the result of human activity, Pacific Islanders have contributed negligibly to greenhouse gas emissions but face the brunt of Anthropocene. While the islanders are coping as best as possible with severe climate events, they may be the canary in the coal mine with regard to the impact of climate change on humanity. Thus, there is a strong case for concerted global effort in assisting the islanders cope with climate change and at reducing the levels of greenhouse gas emissions for the benefit of humanity at large.

Over the past few decades, attempts at adaptation to climate change (current and future) in the Pacific Islands have largely failed to be either effective or sustained. Among the many reasons for this failure may be that most adaptation strategies have been designed and driven by outsiders rather than by persons familiar with island contexts and diversity, especially the sociocultural nuances of particular situations. In a series of eight thematic case studies, written by scientists with an intimate understanding of the Pacific Islands, this chapter explores the reasons behind adaptation failure and explains what needs to improve in the future for adaptation to be both effective and sustained. Case studies focus on rural seawalls, relocation and peripherality as a proxy for autonomous community coping, climate finance, island food systems, adaptation project design, livelihood sustainability and inter-island resettlement. The goal of this chapter is to inform stakeholders how to optimise outcomes from future adaptation interventions, something that is becoming daily more urgent as the pace of twenty-first century climate change increases.