The Changing Climate: American Samoa
Earth’s climate is shaped by complex interactions and dependencies of solar, oceanic, atmospheric and living systems. The changing state of the climate has lead to multiple rises and falls in sea level, variations in the makeup of the atmosphere, and the flourishing and extinction of various species.
The term “climate” is a description of an area’s average weather conditions and how those average conditions change over time. Changes can occur over years, seasons, months or centuries and cover local, regional, or global scales. The term “climate” should not be confused with the term “weather” as “weather” refers to instantaneous changes in the atmosphere on local scales.
A term gaining importance and recognition is “climate change”, which is used to illustrate a significant and ongoing change in average climate conditions or climate extremes. Scientific observations suggest that global climate has changed in the past, is currently changing, and will continue to change in the future. Natural processes that have driven long term climate variations in the past cannot explain the more rapid climate change the Earth has experienced in recent decades.
The only explanation that can account for the rapid changes in climate during the 20th and 21st centuries is the growing impact of increased green house gas emissions due to human activities[1]. Greenhouse gases (carbon dioxide, methane, ozone, nitrous oxide, and others) trap heat in the lower atmosphere causing global warming[2]. Human activities such as burning carbon-based fuel (coal, oil, and natural gas) release the greenhouse gas carbon dioxide to the atmosphere where it traps heat and causes global warming and climate change. Other greenhouse gases also come from industrial activities, deforestation, and large-scale agriculture4.
Changes that are expected as a result of global warming include:
1. Amplification of the water cycle leading to changes in storminess, rainfall, drought, and water resources;
2. Increased extreme weather;
3. Sea level rise;
4. Changes in ocean temperature and chemistry;
5. Increased air temperature4.
Exactly if and how these changes will occur in American Samoa is still unknown.
As the atmosphere warms, sea level rise is one of the more certain outcomes. Sea level rise is already affecting islands within the South Pacific, such as the island of Tuvalu. The rise can be slowed by the global reduction of carbon dioxide emissions; however it is unlikely that sea level rise can be brought to a complete halt. If the burning of fossil fuels were to continue at the current rate, effects could come about more quickly and be severely amplified.
Because evidence points towards a very different future for our climate, our attention should focus on preparation for future changes. Communities can prepare for changes in rainfall (more flooding and more drought will occur in various places of the world). Preparations should also include adapting homes and livelihoods to increased sea level, coastal erosion, and changes in storminess and water resources. Mitigating the amount of stress we put on our environment is another important step towards preserving island lifestyle into the future. Several factors increase the susceptibility of the islands to the effects of sea level rise and climate change. These factors are covered below.
Figure 1 American Samoan fisherman. Fishermen may have already begun observing changes in the surrounding reefs that they rely on as a source of livelihood.
Factor 1: Population Increase along Shorelines
Coastal communities within the islands of American Samoa face higher risks associated with sea level rise and climate change because the population is quickly increasing. From 1970 to 2008 the population of American Samoa increased by about 40,000 people[3]. Much of this population growth has been centered on the island of Tutuila5. Only 30% of the land on Tutuila can be easily accessed and developed. Most of the land available for development is located along the shorelines5. As population increases, so does the island’s dependence on ocean resources for livelihood. As a result, the island’s population is increasingly vulnerable to changes affecting the ocean and coastlines.
Impacts
As the sea level continues to rise, changes that will likely affect the islands include:
• flooding of low lying areas;
• saltwater inundation into fresh water resources;
• coastal erosion[4].
Adaptation measures
Coastal infrastructure, homes and crops can be restructured in order to prepare for these events by:
• building at higher elevations;
• elevating structures in low lying areas with the use of posts;
• retreating from coastal areas if possible;
• sustaining the protective mangroves to solidify the beaches, which will reduce erosion of the beach;
• refraining from constructing sea walls and hard structures. These structures can minimize short term losses but in turn impede the formation of new wetlands and can cause significant beach erosion.
Figure 2 Houses built on posts on the shores of Pangaimotu Beach, Tonga. Elevating houses and infrastructure will likely be an essential adaptive measure along shorelines and river systems as weather intensifies.
Figure 3 Sea wall surrounding Rainmaker Hotel on the island of Tutuila. Sea walls of this type change the natural flow of sand leading to the deterioration the beach.
Factor 2: Dependence on the Ocean’s Resources
Because fishing is an important food resource for the islands of American Samoa, changes in the way we treat the coastal and marine environments need to be considered. To ensure fishing can continue to be a viable source of food and livelihood, ocean resources need to be properly managed and used in ways that are sustainable. Overfishing, destructive fishing methods, anchor damage, waste spills and dredging will likely hasten the negative effects that will come as a result of climate change as changes in water temperature cause coral bleaching.
Deterioration of coral reefs could also lead to increased damage to property along coastlines. Coral reefs acts as a natural buffer against extreme wave action. If this buffer were to break down, more extreme precautions would need to be considered to prepare for periods of extreme wave action brought about by storms and tsunamis.
Adaptive Measures
Strategies that will help keep fishing resources as healthy as possible include:
• Increasing the practice of small pond aquaculture as a food resource. This will take pressure off of reef habitats.
• Relying more heavily on sources of food that are resilient to changes in temperature and climate,
• Legal protection of herbivorous fish that eat algae. Algae can smother struggling reefs so it is important to keep algae growth under control.
• Legal protection of coral reefs, mangroves, and sea grass.
Figure 4 Aquaculture is currently increasing on the island of Tutuila. These resources are important for the future of sustainable livelihood on the islands.
Factor 3: Economic Dependence on Fisheries
American Samoa is home to a large export industry based in Pago Pago. The main industry is dominated by tuna canneries employing 26% of the American Samoa workforce[5]. The impact of such a high percentage of the workforce being dependent on a single industry has been shown through closures and outsourcing, which have led to mass layoffs. Changes in ocean temperatures by climate change would only worsen the problems associated with dependence upon a single industry.
Adaptive Measures
Encourage the development of non-climate dependent businesses. This could be crucial in protecting American Samoa from a severe down-turn in the economy.
Factor 4: Vulnerability to Variations in Weather Patterns
There is a large amount of uncertainty with respect to future variations in rainfall and storm intensity that will result from climate change. An effective way to prepare for uncertain changes in weather patterns is to build a resiliency to flood and drought by having access to multiple sources of food, water, and electricity. By diversifying island resources, less damage will result from extreme climate conditions.
Adaptive Measures
• Increase the number of community and residential water catchment systems to insure the presence of backup reserves of water. By doing so, a greater amount of water can be stored during periods of intense rain and stored for periods of drought.
• Electricity is the most inaccessible source of aid during incidents of natural disaster. Diversifying emergency sources of electricity by increasing the use of solar power as well as storing backup generators should be considered.
• If extreme weather becomes more common, storm resistant crops will need to be considered. Storm resistant crops include tannia, ginger, pineapple, roots and tubers. Plants that are susceptible to rising temperatures and drought should not be relied upon as a food source.
• Rely more heavily upon sustainable agriculture. Sustainable agriculture practices include: diversifying agriculture, relocating crops away from inundation areas, using traditional food preservation methods, buying locally produced foods to sustain local livelihood, and avoiding clearing forests and mono-cropping.
Figure 5 Solar panels are an important source of renewable energy and can also act as a backup source of electricity during emergencies. These solar panels were installed on a carport as a cooperative project between NOAA, American Samoa Community College, American Samoa Power Authority, the Territorial Energy Office and Starkist Inc. Solar Panels.
Factor 5: Decreasing Water Resources by Pollution and Salt Water Intrusion
Water is an extremely valuable commodity. Protection of island water resources is especially important because imported water and desalinization are both extremely expensive. As sea level continues to rise, salt water intrusion into freshwater aquifers will become increasingly episodic, and perhaps a permanent situation. As sea level rises it will likely push salt water upstream where water can seep into the groundwater. During dry periods this affect would likely amplify.
In the village of Amouli salt water intrusion has been reported in three of the fresh water wells. Salt water intrusion into well water occurs as a result of excess pumping and as a result of sea level rise. Over pumping draws the brackish transition zone of the freshwater lens upward. As the transition zone rises to the level of the pumping system the water drawn is made up of brackish water.
Another cause leading to the degradation of water resources is pollution. Pollution from piggeries, construction and mono-cropping can lead to hastened reduction of potable water if not controlled. Adverse affects resulting from pollution are avoidable, unlike affects from sea level rise. Measures can be taken to reduce the depletion of water resources resulting from pollution.
Pollution will become a more difficult problem to resolve as population on the islands continues to grow. Water resource restoration should be undertaken before changes resulting from sea level rise become increasingly problematic.
Adaptation Measures
· To ensure that natural resources of water remain as healthy as possible, watersheds should be protected and restored.
· Additional strategies that can be undertaken by island residents include:
o fixing leaky pipes to reduce unnecessary water loss;
o installing catchment tanks within households or communities to reduce usage of wells;
o using solar water filters to sieve contaminated well water from crops. Doing so can protect reservoirs from contamination;
o storing water in preparation for extreme weather, especially droughts.
o planting native vegetation along rivers and protecting upland vegetation. Doing so will increase water quality by filtering water runoff through soils. This would also protect land from erosion during flooding and provide a habitat for native ecosystems.
o conserving, recovering and reusing fresh water.
o urging government to provide economic incentives to stimulate water conservation and reuse.
Island communities will need to work to reduce vulnerabilities and increase the capacity to adapt in order to successfully respond to the adverse effects of climate change. Adaptation will involve a community effort in deciding how best to reduce damages and increase community resilience.
Figure Credits
Fig 1: http://www.americansamoa.travel/faa-samoa
Fig 2: http://www.cepolina.com/beach_Pangaimotu.htm
Fig 3: http://mstecker.com/pages/amsamoa_fp.htm
Fig 4: http://www.spc.int/aquaculture/index.php?option=com_countries&view=country&id=1&Itemid=4
Fig 5: http://www.esrl.noaa.gov/gmd/obop/smo/groundsroof.html
5
[1] Oreskes, N. (2004) Beyond the Ivory Tower: The Scientific Consensus on Climate Change. Science. Bos. 306 no. 5702 p.1686 doi: 10.1126/science.1103618
[2] Solomon, Susan, Gian-Kasper,Plattner, Reto Knutti, and Pierre Friedlingstein. (2009) Irreversible climate change due to carbon dioxide emissions. PNAS 2009 106 (6) 1704-1709; published ahead of print January 28, 2009, doi:10.1073/pnas.0812721106
[3] Crossett, K.M., C.G. Clement, S.O. Rohmann. (2008) Demographic Baseline Report of U.S. Territories and Counties Adjacent to Coral Reef Habitats. Silver Spring, MD: NOAA, National Ocean Service, Special Projects. 65 pp.
[4] Fletcher, Charles, Robynne Boyd, William J. Neal, Virginia Tice. (2010) Living on the Shores of Hawai’i: Natural Hazards, The Environment, and Our Communities. University of Hawai’I Press.
[5] Hamnett, Michael P., Cheryl L. Anderson. Impact of ENSO Events on Tuna Fisheries in the U.S. Affiliated Pacific Islands. Social Science Research Institute. University of Hawaii. SOEST 00-03. JIMAR Contribution 00-330