Pacific Islands and climate change
As human numbers increase and 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 Nino-Southern Oscillation (ENSO).
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 and prone to natural disasters, but their limited natural resources; relative isolation; extremely open economies; rapidly increasing populations and urbanisation; poorly developed infrastructure; and limited resources and skills affect their capacity to manage the impact of, and adapt to, changes to the climate and sea levels.
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. Saltwater wash-over during storms would contaminate soil and the fresh water lenses which inhabitants depend on for water and growing food. Coastal villages and industries such as fisheries, aquaculture, agriculture and tourism would also be at risk. Many of the islands are already experiencing climate risks such as cyclones, sea-level changes, droughts and environment-related health issues. The Pacific leaders have formally acknowledged that climate change presents the greatest risk to the livelihoods, security and wellbeing of Pacific Islanders.
Sea level monitoring project
The South Pacific Sea Level and Climate Monitoring Project was established in 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.
Between July 1991 and December 2000 sea level and meteorological monitoring stations were installed at 11 sites, one each in the Cook Islands, Fiji, Kiribati, the Marshall Islands, Nauru, Papua New Guinea, Solomon Islands, Tonga, Tuvalu, Vanuatu and Samoa. Between 2001 and 2005 another station was established in the Federated States of Micronesia and continuous global positioning systems (CGPS) were installed in numerous locations to monitor the islands’ vertical movements. Data continues to be collected, analysed and disseminated to partner countries and the scientific community.
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 is reflected back. 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 to 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.
Measurements of sea level vary considerably over time due to variations in tides, storm events such as cyclones, ocean events such as El Nino 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 is used to remove the noise and gain a more accurate picture of sea-level change.
As the sea-level record becomes longer, the relative sea-level trend estimates become more stable and reliable.
Table 1: Sea-level trends
|Location||Installation date||Sea-level trend (mm/yr)|
|Cook Islands||Feb 2003||+5.5|
|Federated States of Micronesia||Dec 2001||+17.7|
|Marshall Islands||May 1993||+5.2|
|Papua New Guinea||Sept 1994||+8.0|
|Solomon Islands||Jul 1994||+7.7|
Recent short-term relative sea-level trends in the project area based upon SEAFRAME data to December 2011. The record at Federated States of Micronesia is considerably shorter, resulting in a comparatively large trend.
New rainfall-outlook service
AusAID and the Australian Bureau of Meteorology have also 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, disaster managers and farmers) are also trained to use the data to determine water allocations, emergency response preparedness and to assist farmers to plan crop rotations. A particular example can be found in Fiji’s sugarcane industry.
Sugarcane in Fiji
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. This knowledge will help farmers to mitigate some of the negative effects of climatic variability and capitalise on positive events. Workshops have assisted farmers and sugar researchers to improve their understanding of the impact of weather on sugar, and to understand general climate trends, local climatology, seasonal forecasting and weather maps.
South Pacific Sea Level and Climate Monitoring Project www.bom.gov.au/pacificsealevel/index.shtml
Reports from the South Pacific Sea Level and Climate Monitoring Project www.bom.gov.au/oceanography/projects/spslcmp/reports.shtml