There are now discernible global effects from human-produced greenhouse gas (GHG) emissions. In the Pacific region climate change and sea-level rise, coupled with natural variability, have severely impacted the economic, environmental and socio-cultural sectors of Pacific people and countries. The following vulnerable sectors need urgent attention: coastal areas, water resources, agriculture, human health, cultural and traditional heritage sites, fisheries, forestry and social and economic dimensions. Adaptation strategies are now being planned to deal with the impacts of climate change and sea-level rise in the region; an Integrated Coastal Management (ICM) concept being promoted by SPREP serves as a potential process in addressing the impacts of climate change and environment changes.
The main objective of this paper is to provide an overview of the impacts which changes in climate, sea level and natural variability, caused by anthropogenic greenhouse gas emissions, are having on the economic and environmental sectors of Pacific island countries (PICs).
The Intergovernmental Panel on Climate Change (IPCC) reported in 1995 that there are now discernible effects of human activity on global temperature and climate. There continues to be substantial scientific uncertainty as to the magnitude of these impacts on population, economic, environment, agriculture, forestry and other sectors of the ecosystems at global, regional and national levels. These uncertainties do not mean that increasing greenhouse gas (GHG) emissions can be safely ignored; rather, they call for urgent response strategies to be developed, especially for the PICs.
Pacific island countries (PICs) are among the most vulnerable to impacts of climate and sea-level changes, particularly when these impacts are coupled with other environmental changes. The majority of the population, socio-economic activities and infrastructure are located along or near the coastal areas. Even on large high islands, the inhabitable land tends to be on the coastal fringe and therefore is highly vulnerable to impacts of climate change and sea-level rise. For example, climate change due to enhanced warming caused by increasing quantities of greenhouse gases in the atmosphere could mean changes in storm frequencies and intensity and lead to increased risk of flooding. It could upset sediment balances of the islands, leading to beach erosion and displacement of settlements and infrastructure. Of major concern is a possible increase in the intensity and magnitude of extreme climatic events, such as tropical cyclones, storm surges and El Niño events.
The biophysical and socio-economic environments of PICs are already sensitive to changes in both mean extreme atmospheric and oceanic conditions. Their vulnerability can be partly offset by the intrinsic resilience of natural systems and by decisions to manage systems in ways which increase their ability to withstand the adverse effects of climatic and oceanic conditions. Not withstanding such characteristics and interventions, the environment of the PICs is undeniably susceptible to both extreme and anomalous persistent events occurring under present day conditions. Vulnerability and actual harm are enhanced by increased human pressure on natural systems. Given this existing sensitivity, there can be little doubt of the potentially devastating consequences should anticipated changes be manifest in the future. The repercussions would threaten the life-supporting capacity of natural systems and the sustainability of human habitation. The key questions therefore are: how will the impacts manifest themselves; and what are the most appropriate responses for avoiding, minimising and adapting to these impacts? Since PICs experience some of the greatest interannual variations in climatic and oceanic conditions many of their natural systems are well adapted to stresses that result. Many strategies that PICs might adopt to adapt to climate change are usually the same as those that constitute sound environmental management, wise use of resources and appropriate responses to present-day climate variability.
Impacts of Climate Change
The impacts of global climate change can be best described in terms of the effects on the biophysical and human systems in the South Pacific. Climate change can affect both long-term changes and extreme events by changing the temperature, wind, rainfall and oceans. These direct effects can contribute to the increased frequency or severity of drought, fire and other biological hazards. Temperature increase will cause thermal expansion of the ocean, resulting in sea-level rise. The combined effect of GHG-induced climate change and sea-level rise would contribute to coastal erosion/land loss, flooding, salinisation, intrusion of saltwater in the groundwater. The quantity and quality of available water supplies affects agricultural activities, production and human health. Any changes in ocean circulation and upwelling could affect the fish populations and catch. Tourism, a very important economic activity in the PICs, could be affected through beach erosion, loss of land and degraded reef ecosystems, as well as the changes in the seasonal patterns of rainfall.
The Intergovernmental Panel on Climate Change (IPCC) in its Second
Assessment Report (SAR) projected a global average temperature increase by the year 2100 of the order of 1.5–4.5°C and a consequent sea-level rise of the order of 15–95cm. Results from observational data show that since the late 19th century global mean surface air temperature has increased by 0.3–0.6°C. Global sea level has risen by 10–25cm and much of this rise may be related to the increase in global mean temperature. There is also evidence that the El Niño–Southern Oscillation (ENSO) phenomenon has a major influence on climate variability and change, and that the frequency of ENSO events has increased since 1977. (Trenberth, K. E. and Hoar, T. J. 1997; El Niño and climate change: Geophys. Res. Lett. Vol. 24 , No. 23 , p. 3057-3060.)
A 1997 report from New Zealand’s National Institute of Water and Atmospheric research (NIWA) shows that since 1920 temperatures rose 0.6–0.7°C in Noumea (New Caledonia) and Rarotonga (Cook Is) which is greater than average worldwide increases. Based on data from 34 stations in the Pacific from about 160 E. and mostly south of the equator, surface air temperatures increased by 0.3–0.8°C this century, with the greatest increase in the zone south-west of the South Pacific Convergence Zone (SPCZ). This is well in excess of global rates of warming. Compilation of data by NIWA and Meteo France shows a general change in the South Pacific climate from the mid-1970s:
Kiribati, the northern Cook Islands, Tokelau and northern parts of French Polynesia have become wetter;
New Caledonia, Fiji and Tonga have become drier;
Samoa, eastern Kiribati, Tokelau, north east French Polynesia have become cloudier and have warmer night time temperatures;
New Caledonia, Fiji, Tonga, the southern Cook Islands and south west French Polynesia have become warmer and sunnier;
Western Kiribati and Tuvalu have become sunnier.
The records also indicate that since 1977, rainfall increased in the north-east and decreased in the south-west of the Pacific. Interannual variations in temperature and rainfall were found to be associated with El Niño events, resulting in water shortages and drought in Papua New Guinea, Marshall Islands, Federated States of Micronesia, American Samoa, Samoa, Tonga, Kiribati and Fiji. This research also noted that since 1977 the South Pacific Convergence Zone (SPCZ) had shifted abruptly 150km eastwards. The changes observed in the twentieth century are considered to be consistent with climate change theory concerning likely changes from increasing anthropogenic emissions of GHGs.
The ‘best estimate’ of temperature and sea-level rise as projected by a mid-range IPCC scenario IS92a predicts a sea-level rise of about 50cm by 2100. Current observational data indicate a regional average sea-level rise of about 2–3cm which is not far from the business as usual (BAU) scenario result. At present little can be said with any certainty about regional or national scale changes attributable to such scenarios of climate change and sea-level rise.
The present global average sea-level rise is 2mm per year but data compiled from the 11 tide gauges by the National Tidal Facility, Flinders University of South Australia, from 1992–1997 shows an accelerated SLR of up to 25mm/yr, more than 10 times the global trend this century. This finding was validated by satellite data showing 2–3cm per year rises particularly in the region from Papua New Guinea southeast to Fiji. The cause and duration of this variation is unknown, but is likely to be related to ENSO.
Recent modelling by Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) on the effects of the “business as usual” (BAU) scenario (IS92a) on Pacific island countries determined that past human emissions of greenhouse gases have already built an inevitable 5–12cm sea-level rise into natural systems, which would be expected to peak between 2020–2025. If all countries strictly adhered to their Kyoto Protocol emissions reduction targets, and if technological developments then permistted a complete cessation of GHG emissions after 2020, total global sea-level rise would be of the order of 14–32cm, peaking from 2050–2100.
Global climate models (GCMs) currently suggest a doubling of C02 concentrations in the atmosphere will increase sea-surface temperatures by 1°C and increase rainfall intensity in the central equatorial Pacific. Although the second assessment of IPCC did not reveal a consensus regarding tropical cyclones in a changed climate regime, recent research has indicated possible intensity increase of 10–20% with a doubling of C02. A great deal of international effort has enabled the identification of seasonal and interannual trends in oceanic conditions, but scientists are not yet in a position to identify long-term trends in temperature and salinity. According to the statistics of tropical cyclones (TCs) between 1940 and 1994, the average number of TCs per year is seven. However, an increase in TC frequency to more than eight is closely linked to the frequency of El Niño events. Although the general TC season is between October and May, most TCs occur between January to March each year. Recent NIWA research which analysed 20 years’ data shows that during strong El Niño events there are markedly greater chances of cyclones affecting Tuvalu, Samoa, Tonga, Cook Islands and French Polynesia. In addition, the overall risk for the region increases by 28%.
Present numerical models cannot predict changes in frequency, area of occurrence, time of occurrence, mean intensity and maximum intensity of TCs. However, TCs usually occur between latitudes 8°S and 20°S and longitude 145°E and 125°W. The probability of a TC occurring is greatest near 8°S and decreases with increasing latitude. During an El Niño event the chance that any one TC will be severe increases by 40%. The IPCC concludes that it is still very much open as to whether the frequency, area of occurrence, time of occurrence, mean intensity or maximum intensity of tropical cyclones will change as a consequence of global warming
Recent variations over the tropical Pacific Ocean and the surrounding land areas are related to the fact that since the mid-1970s El Niño events have been relatively more frequent or persistent than the opposite La Niña phase (Trenberth and Hoar). The ENSO phenomenon is the primary mode of climate variability on the 2–5 year time scale. Thus, the current large interannual variability in the rainfall associated with ENSO is likely to dominate over any effects attributable to global warming.
Vulnerability assessments undertaken in the Pacific over the last few years reveal that climate change will impose diverse and significant impacts on Pacific Island countries.
The most significant and more immediate consequences for Pacific island countries are likely to be related to changes in rainfall regimes and soil moisture budgets, prevailing winds (both speed and direction) and in short-term variations in regional and local sea levels and patterns of wave action.
Vulnerability assessments undertaken for PICs show that they;
are highly vulnerable to changes in climate and sea-level;
have a large natural resilience impaired by human pressures;
make insignificant contributions to global environmental changes.
Although the form that climate change will take in the Pacific region is far from certain, severe impacts are likely to be felt in a number of biophysical and traditional-cultural systems. These are discussed below and include:
Most PICs have large coastal areas compared to their total land areas and are subject to human pressure, exacerbated by storm and wave action. The most significant impacts include erosion and land loss; inundation and wave overtopping during extreme events; and loss of infrastructure. There have been reported land losses from Kiribati and Tuvalu from rising sea levels: on Tuvalu, the motu of Tepuka Savilivili disappeared beneath the sea late last year; while on Kiribati the motu of Tebua Tarawa, which used to be a landmark for fishermen, is now under water also.
Water resources remain very critical for many of the Pacific island countries. For instance most low-lying atoll countries rely almost entirely on rainwater (Tuvalu, and northern atolls of Cook Islands) with some storage capacity in the freshwater lens (eg: Kiribati and Marshall Islands). Even on high islands, changes in rainfall patterns, either forced by large interannual variations and ENSO, or by a changed climate regime, have caused severe shortages of water. Drought in PNG, Federated States of Micronesia, Marshall Islands and Fiji is a manifestation of such variations in climatic and oceanic conditions. If the recent increase in the frequency of El Niño events continues, it is likely that drought will continue to be a more frequent event in these countries.
Agriculture remains a major socio-economic activity in the PICs. Under conditions of changed climate regimes, traditional crops would be affected placing heavy reliance on imported foodstuffs. In this case agricultural systems would have to change, to reflect changes in temperature and moisture. Increased temperatures will cause heat stress for many agricultural plants and would lead to drought particularly during the dry season. Increased concentrations of CO2 could increase plant growth except for sugar cane and maize. The sugar industry of Fiji is currently being affected by the long drought. More research work needs to be focused on the effects of climate change and sea-level rise on agricultural food crops in PICs.
Climate change and its impact on human health is a new area of research. One of the problems is that we do not know enough about what might happen in the future. This highlights the importance of using integrated assessment models (IAM) for assessing climate change impacts on human health. At present there is a significant number of health-related disasters in the developing world. There is a threat posed by infectious vector-borne and water-borne diseases such as malaria and dengue in PICs. As temperatures rise, disease-carrying vectors such as mosquitos will move into areas which previously were too cool for them to survive. Outbreaks of dengue are on the rise and there have been reports of malaria incidence in areas which previously did not have malaria—for example, in the highlands of Papua New Guinea. Future studies would include:
identification of vulnerable population to health risk;
development indicator species of vectors, and response strategies and;
establishment of early warning systems for important climate events such as ENSO variations or tropical cyclones.
Cultural and Traditional Heritage
Sea-level and climate changes coupled with environmental changes have destroyed very important cultural and spiritual sites of some PICs and continue to threaten some unique traditional heritage sites in Federated States of Micronesia, Tuvalu, Marshall Islands, Niue and Kiribati. These sites include burial caves, spiritual grounds, marine protected sites and cemeteries. They do not have monetary values but they are important sites for PICs. There are still cultural and natural heritage sites which are highly valued by many Pacific island people. Some of these values and traditions are compatible with modern conservation and environmental practices; therefore, more than ever before, priority action is needed to address the following:
research into traditional knowledge and practices of conservation and environmental management;
conduction of an inventory of traditional sites and marine management;
encouragement of practices that enhance complementary use of modern science and technology and traditional knowledge and wisdom;
promotion of the transmission of the above to younger generations in the Pacific.
Studies of the impacts of climate variation on tuna fisheries in the Pacific Ocean have been undertaken by the Secretariat of the Pacific Community (SPC). One such study found that the tuna resource is very closely linked to the position of the warm pool in the Eastern Equatorial Pacific Ocean, which extends from 150°W to 90°W and 5°N to 5°S during El Nino episodes, and from 135°E to 180°W, 5°N to 5°S when ENSO is in the La Nina phase. The warm pool is an area of low primary production, which makes the proximity of the tuna resource surprising because tuna need to consume 10% of their body weight each day. The reason for this association may be the positioning of the convergence zone along the eastern boundary of the warm pool, where up-welling enables secondary production on which tuna feed. This may provide a possible mechanism for replenishing productivity in the warm pool. Simulation studies indicate that secondary production (up-welling) enables the concentration of tuna in otherwise ‘poor’ productivity areas as a result of convergence zones. It is not clear as to how tuna fishery resources will be affected under a changed climate regime as a result of global warming, even assuming management of the resource in the next 20 years is effective and that there remains a viable tuna fishing industry in the Pacific.
Our current understanding of the complex interrelationships between forests and climate change in the Pacific is not well-developed and therefore is generally insufficient for informed policy-making and management strategies. Of importance, forests act as great carbon sinks in reducing CO2 in the atmosphere. However, IPCC projects that substantial changes are likely to occur under doubled equivalent CO2 equilibrium conditions. It is estimated that one-third (one-seventh to two-thirds depending on the region) of the existing forested areas of the world will undergo major changes in broad vegetation types. Greatest changes are likely to occur in high latitudes and minor changes in the tropics. Because the rate of climate change is likely to be faster than the rate at which forests grow, mature, reproduce and re-establish themselves, species composition is likely to change (forest types may disappear, new species and ecosystems may become established instead). The transition from one forest type to the other may contribute large amounts of carbon dioxide into the atmosphere as decaying plant matter releases carbon dioxide. It is not at all clear how climate change will affect forest types in the Pacific although shifts and contraction of some forests such as mangroves and strand vegetation are likely to occur due to the effect of sea-level change. Research work on examining the impacts of climate change on forestry (species composition, diversity, etc) in PICs is encouraged.
Social and economic dimensions
The IPCC assessment of the social and economic dimensions of climate change makes little reference to Pacific Island Countries. All islands are treated as if they are the same. For the world as a whole the IPCC estimates a net loss for 2 x C02 of about 1.5–2.0% of global Gross National Product (GNP). Developing countries are estimated to have net loss of 2-9% GNP. The social and economic dimension of Global Climate Change have a number of implications for Pacific island countries such as:
(a) PICs make a small or negligible contribution to GHG;
(b) They are among the countries which are most impacted; and
(c) Knowledge of relevant parameters is very low.
Thus Pacific island countries should take precautionary approaches and should acquire more understanding and knowledge about the effects than the causes, and more about adaptation than mitigation. Understanding effects and adaptation is essential in the political arena and thus public awareness is important for the Pacific region. For PICs, the different adaptation options must deal with a broad range of impacts to achieve a balanced sustainability. An important adaptation strategy that may be useful to deal with these impacts at national level would be Integrated Coastal Management (ICM). Integrated coastal management is a continuous, iterative, adaptive, and consensus-building process comprised of a set of related tasks, all of which must be carried out to achieve a set of goals, including adapting to the effects of climate change. The dimensions of integrated coastal management include:
integration of policies and programmes across and among sectors of the economy, eg, economic development, transportation, recreation, agriculture;
integration among agencies involved in coastal management at all levels of government, including both vertical (national, sub-national and local) and horizontal (across the same level of government);
integration between public and private sector management activities; integration between management actions that affect the land and water environments of coastal areas, and those areas upstream and upwind of coastal areas;
integration among the disciplines of coastal management including ecology, economics, engineering, and political science;
Most Pacific island governments view climate change and sea-level rise and natural variability as priority issues, recognising that they significantly impact the economic, environment, social, cultural and traditional sectors of PICs. However, governments wish to know what they have to do to address the problem. The traditional and cultural dimension involves the environmental influence on both people and culture. Traditional knowledge has governed the activities and survival of people in the region both in the past and present. From a socio-economic perspective there has been a change from subsistence to a dual economy. Issues that need to be addressed include population concentration; the location of infrastructure; food security; culture; and a wide range of other activities that are integral to sustainable livelihoods in Pacific island countries.
The way ahead
The response options that have been, and will continue to exist in the region, include mitigation, migration, foreshore stablilisation, resettlement and decentralisation to adapt to the impacts of climate and sea-level changes. All these need planning as they have policy implications. Thus the future direction will have to be researched so that some response strategies can be planned and recommended for future adaptation. An integrated coastal management (ICM) approach may be most useful in the development and implementation of adaptation strategies. This approach could be valuable, with or without climate change, to permit effective planning to achieve sustainable development at the national level.