South Pacific Sea Level and Climate Monitoring Project

Background Sea level monitoring project Monitoring stations Sea level trends New rainfall outlook service Sugar cane in Fiji   Background As human numbers increase and more fossil fuels such as coal, oil and gas are used and forests cut down, the global climate will continue to change through the ‘enhanced greenhouse effect’. Scientists have linked this change to rising sea levels, higher temperatures, greater variability in rainfall patterns, more intense tropical cyclones and changes in the onset of the El Niño-Southern Oscillation (ENSO). In January 2004 Cyclone Heta lashed the tiny island of Niue with winds of up to 300 kilometres per hour and huge waves. Much of the infrastructure was destroyed and the fishing and agricultural based economy was damaged. © AusAID The small island states of the Pacific are extremely vulnerable to the projected effects of climate change. Not only are they surrounded by large expanses of ocean, but their limited natural resources; proneness to natural disasters; relative isolation; extremely open economies; rapidly increasing populations and urbanisation; poorly developed infrastructure; and limited funds, human resources and skills limit their capacity to manage the impact of and adapt to future climate and sea-level change. Climate change could affect Pacific island countries in a range of ways, depending on their specific geography and location. Flooding and coastal erosion would worsen with higher sea levels. Salt water wash-over during storms would contaminate soil and the fresh water lenses on which inhabitants depend for obtaining water and growing food. Coastal villages and industries such as fisheries, aquaculture, agriculture and tourism would be at risk. Climate change is projected to exacerbate health problems, placing additional stress on the already over-extended health systems of most small islands. The atoll islands of Tuvalu, barely exceed 2-3 metres above sea level and are composed of highly mobile sediments. They are susceptible to shoreline erosion and wash-over during storms. Farmers are beginning to grow their taro crops in tin containers filled with compost instead of traditional pits to avoid salt contaminated soil. Used with permission of the Pacific Island - Climate Prediction Project, Australian Bureau of Meteorology Sea level monitoring project South Pacific sea level and climate monitoring stations © Commonwealth of Australia 2007, Bureau of Meteorology (ABN 92 637 533 532) The South Pacific Sea Level and Climate Monitoring Project developed as an Australian response to concerns voiced by Pacific Island countries about the potential effects of climate change. The project aims to provide an accurate long-term record of sea levels in the area for partner countries and the international scientific community, and enable the former to make informed decisions about managing their coastal environments and resources. The first two phases (from July 1991 to December 2000) established sea level and meteorological monitoring stations at 11 sites, one each in the Cook Islands, Fiji, Kiribati, the Marshall Islands, Nauru, Papua New Guinea, the Solomon Islands, Tonga, Tuvalu, Vanuatu and Samoa. During the third stage (2001–2005) another station was established in the Federated States of Micronesia (FSM) and continuous global positioning systems (CGPS) were installed at many of these locations to monitor the islands’ vertical movements. During the fourth, five-year phase (2006–2010) data will continue to be collected, analysed , stored and disseminated and personnel will be trained to assist with the interpretation of the data. Monitoring stations Sea level and climate monitoring stations installed in 12 sites throughout the Pacific. © Commonwealth of Australia 2007, Bureau of Meteorology (ABN 92 637 533 532) The monitoring stations use the SEAFRAME (Sea level Fine Resolution Acoustic Measuring Equipment) system, which has also been installed around Australia. The equipment has built-in sensors that measure: water level wind speed and direction, and maximum wind gust air and water temperatures atmospheric pressure vertical changes in land level. The SEAFRAME monitoring stations use an Aquatrak sensor, which operates acoustically. A pulse of sound is fired down a tube to the surface of the water, and then is reflected back from the surface. Measuring the time taken for the sound to travel from the sensor and back allows the sea level to be determined. The speed of sound varies with temperature, humidity and air pressure and the Aquatrak sensor automatically compensates for these variations, which are also measured by the SEAFRAME station. The equipment has the capacity to measure sea level changes within one millimetre accuracy, every six minutes, which is important for recognising small changes. Other measurements are recorded once every hour. The sea level and climate data are regularly recorded and transmitted to the Australian Bureau of Meteorology National Tidal Centre (NTC) in Adelaide. Sea level trends Measurements of sea level vary considerably over time due to variations in tides, storm events such as cyclones, ocean events such as El Niño and catastrophic events such as volcanic eruptions and earthquakes. These variations are referred to as ‘noise’. This noise makes it difficult to determine any long-term change in the sea level, so other information such as tidal analysis and barometric pressure are used to remove the noise and gain a more accurate picture of sea level change. Figure 1: Evolution of short-term relative sea level trends (mm/year) at SEAFRAME stations. © Commonwealth of Australia 2007, Bureau of Meteorology (ABN 92 637 533 532) Figure 1 shows the short-term sea level trends measured by the South Pacific stations. In the early years, the trend appeared to indicate an enormous rate of sea level rise. Later, due to the 1997–1998 El Niño, when the sea level fell 20 cm below average, the trend actually went negative and remained so for the next year or more. Only in mid-1999 did the trend again turn upward. Given that the record is relatively short, it is still too early to deduce a long-term trend, but a number of clear results are emerging. The sea level records for all stations demonstrate coherent sea level rise that are in line with global trends estimated from satellite-based altimeters over the same period. Table 1: The net relative sea level trend estimates, taking into account the inverted barometric pressure effect and vertical movements in the observing platform Location Length of data (months) Sea level trend (mm/yr) Barometric pressrue contribution (mm/yr) Vertical tide gauge movement contribution (mm/yr) Net sea level trend (mm/yr) Cook Islands 147 +0.7 +0.27 -0.3 +0.7 FSM 42 +19.1* -1.24* N/A +20.3* Fiji 152 +3.2 +1.22 -0.3 +2.3 Kiribati 145 +6.6 +0.51 -0.1 +6.2 Marshall Islands 140 +5.3 +0.25 +0.5 +4.6 Nauru 142 +7.5 +0.53 -0.0 +7.0 Papua New Guiena 114 +6.7 +1.54 +0.2 +5.0 Samoa 147 +5.1 +0.41 +1.1 +3.6 Solomon Islands 127 +3.7 -0.24 +0.4 +3.5 Tonga 148 +9.2** +0.88 +0.1 +8.2** Tuvalu 145 +5.0 +0.58 +0.1 +4.3 Vanuatu 138 +4.5 +1.41 -0.3 3.4 * The rate at FSM is derived from a comparatively short data record. ** Tonga’s rate is larger than that of its neighbours . The vertical motion of the whole island is yet to be quantified. New rainfall outlook service AusAID and the Australian Bureau of Meteorology have provided new software and training for the staff at the National Meteorological Services in the Pacific Islands so they can provide better meteorological services. Stakeholders (such as water resource managers, farmers, disaster managers etc) are also trained to use the data for water allocations, the preparedness of emergency services and assisting farmers to plan of crop rotations for the following season. Sugar cane in Fiji Ploughing a field for sugar cane production in Nadi, Fiji Used with permission of the Pacific Island - Climate Prediction Project, Australian Bureau of Meteorology The sugar industry is Fiji’s third-highest earner and is totally dependent on rainfall. It is essential for farmers to understand the impact of climatic patterns on sugarcane and sugar yields so they can plan planting, herbicide and fertiliser application and harvesting to mitigate some of the negative effects of climatic variability and capitalise on positive events. Workshops have assisted farmers to improve their understanding of the impact of weather on sugar, understand general climate trends, local climatology, seasonal forecasting and weather maps. The project is assembling an archive of sea-level and related climate data that provides information about sea-level variability and change required to sustainably manage near-shore and coastal resources, and to develop policies and strategies for responding to long-term trends. It is also developing the capability within national and regional agencies to acquire, manage and disseminate data and information about sea-level variation. Sources: South Pacific Sea Level and Climate Monitoring Project http://www.bom.gov.au/pacificsealevel/index.shtml Pacific Islands – Climate Prediction Project http://www.bom.gov.au/climate/pi-cpp/sugarcane_fiji.shtml Reports from the South Pacific Sea Level and Climate Monitoring Project http://www.bom.gov.au/oceanography/projects/spslcmp/reports.shtml UNEP/WMO report Climate Change 2001: Impacts, Adaptation and Vulnerability http://www.grida.no/climate/ipcc_tar/wg2/index.htm Resources: AusAID Map of the Pacific Islands