Friday, August 07, 2009
Tulele Peisa Executive Director
For some time now, Carteret Islanders have made eye-catching headlines: “Going, going… Papua New Guinea atoll sinking fast”. Academics have dubbed us amongst the world’s first “environmental refugees” and journalists put us on the “frontline of climate change.”
So perhaps you have heard how we build sea walls and plant mangroves, only to see our land and homes washed away by storm surges and high tides. Maybe you can even recognise the tragic irony in the fact that the Carterets people have lived simply (without cars or electricity) — subsisting mainly on fish, bananas and vegetables — and have therefore not had much of a “carbon footprint”.
You might know that encroaching salt water has contaminated our fresh water wells and turned our vegetable plots into swampy breeding grounds for malaria-carrying mosquitos. Taro, the staple food crop, no longer grows on the atoll. Carterets Islanders now face severe food shortages, with government aid coming by boat two or three times a year.
However, the story you have not likely read is the one of government failure and the strategy we developed in response, so as to engineer our own exile from a drowning traditional homeland.
Carterets people are facing, and will continue to face, many challenges as we relocate from our ancestral grounds. However, our plan is one in which we remain as independent and self-sufficient as possible. We wish to maintain our cultural identity and live sustainably wherever we are.
While we call on the Papua New Guinea government to develop policy, we are not sitting by. Instead, we now want to see the media headlines translate into practical assistance for our relocation program. And we hope our carefully designed and community-led action plan can serve as a model for communities elsewhere that will be affected by climate change in the future.
Six islands become seven
Situated 86 km Northeast of Bougainville, the main island in the autonomous region of which the Carterets form part, our atoll is only 1.2 meters above sea level. They say evacuation of the islands was inevitable as for many, many years erosion has been doing its work.
“King tides”, or particularly high tides, are now doing worse. Originally the Carterets were six islands, but Huene was split in half by the sea and so now there are seven. In 1995 a wave ate away most of the shorelines of Piul and Huene islands. Han island, as shown in the video-brief, has suffered from complete inundation.
What climate change’s exact role is, even experts are hard put to answer. Debate has raged over whether the islands are sinking, if tectonic plates play a role, and whether sea levels are in fact rising. We do not know much about science, but we watch helplessly as the tides wash away our shores year in and year out. We also know that we are loosing our cultural heritage just as the sea relentlessly wipes out our food gardens. We do not need labels but action.
Tulele Peisa’s plan is for Carteret Islanders to be voluntarily relocated to three locations on Bougainville (Tinputz, Tearouki and Mabiri) over the next 10 years. Our immediate need is for funding so that we can accomplish the initial 3-year phase of our Carterets Integrated Relocation Programme .The list of objectives is long and challenging but our plan is holistic so we have faith it will succeed.
Firstly, the three host towns have a population of 10,000 and we are cognisant of the many complexities involved in integrating the Carteret people into existing communities that are geographically, culturally, politically and socially different. Therefore exchange programs involving chiefs, women and youth from host communities and the Carterets are in progress for establishing relationships and understanding.
While this is going well, the next urgent steps include securing more land and surveying and pegging site boundaries. Next comes constructing housing and infrastructure for 120 families. With the help of the Catholic Church in Bougainville, the relocation programme aims to provide design and carpentry services and local materials for basic housing for these families.
We also need to get on with implementing agricultural and income generation projects (like the rehabilitation of cocoa and coconut blocks), as well as education, health and community development training programmes.
“The plan is slow to achieve but covers all areas dealing with human relations and has adaptation alternatives, such as small cash income activities for relocated families,” said elder Tony Tologina, chief of the Naboin clan. On the long term, we want to build the capacity of Tulele Peisa to be certain it can carry out its objectives and also develop it as a resource agency for the Carterets and host communities on Bougainville.
“Tulele Peisa is our own initiative and will continue to co-ordinate and facilitate the relocation of our island people. After the relocation, TP will continue to provide monitoring and evaluation skills and further focus on development options available to our people,” said Rufina Moi, woman chief.
Blogger note: to download the full plan, visit the above link.
Thursday, August 06, 2009
Langley, J.A., McKee, K.L., Cahoon, D.R., Cherry, J.A. and Megonigal, J.P. 2009. Elevated CO2 stimulates marsh elevation gain, counterbalancing sea-level rise. Proceedings of the National Academy of Sciences, USA 106: 6182-6186.
The authors write that "tidal wetlands experiencing increased rates of sea-level rise (SLR) must increase rates of soil elevation gain to avoid permanent conversion to open water." As for how that might happen, they note that "root zone expansion by accumulation of plant material is essential to maintaining a constant surface elevation relative to rising sea level."
What was done
In Kirkpatrick Marsh -- a microtidal subestuary of Chesapeake Bay, where each of several 200-m2 plots was outfitted with a surface elevation table (SET) to measure soil elevation change -- Langley et al. exposed half of the plots to an extra 340 ppm of CO2 for a period of two years, while "data from a greenhouse mesocosm experiment (Cherry et al., 2009) were used to examine how elevated CO2 might affect elevation response under simulated SLR scenarios."
What was learned
The five researchers report that the extra CO2 of their marsh experiment increased fine root productivity by an average of 36% over the two-year study, and that aboveground biomass production was increased by as much as 30%, "consistent with a 20-year record of elevated CO2 treatment in a previous CO2 study on the same marsh (Erickson et al., 2007)." In addition, they say the elevated CO2 caused an increase in root zone thickness of 4.9 mm/year compared with only 0.7 mm/year in the ambient CO2 treatment, with the result that there was "a slight loss of elevation in ambient CO2 (-0.9 mm/year) compared with an elevation gain (3.0 mm/year) in the elevated CO2 treatment." Furthermore, they report that the greenhouse mesocosm experiment of Cherry et al. (2009) "revealed that the CO2 effect was enhanced under salinity and flooding conditions likely to accompany future SLR."
What it means
Langley et al. conclude that "by stimulating biogenic contributions to marsh elevation, increases in the greenhouse gas, CO2, may paradoxically aid some coastal wetlands in counterbalancing rising seas." In this regard, they say their findings "bear particular importance given the threat of accelerating SLR to coastal wetlands worldwide," citing the recent EPA report of Reed et al. (2008), which suggests that "a 2-mm increase in the rate of SLR will threaten or eliminate a large portion of mid-Atlantic marshes." Once again, however, the proven and positive growth-promoting effect of atmospheric CO2 enrichment more than compensates for its hypothetical and negative global-warming effect.
Cherry, J.A., McKee, K. and Grace, J.B. 2009. Elevated CO2 enhances biological contributions to elevation change in coastal wetlands by offsetting stressors associated with sea-level rise. Journal of Ecology 97: 67-77.
Erickson, J.E., Megonigal, J.P., Peresta, G. and Drake, B.G. 2007. Salinity and sea level mediate elevated CO2 effects on C-3-C4 plant interactions and tissue nitrogen in a Chesapeake Bay tidal wetland. Global Change Biology 13: 202-215.
Reed, D.J. et al. 2008. Site-Specific Scenarios for Wetlands Accretion as Sea Level Rises in the Mid-Atlantic Region. Section 2.1. Background Documents Supporting Climate Change Science Program Synthesis and Assessment Product. Titus, J.G. and Strange CO2, E.M. (Eds.). EPA 430R07004, U.S. Environmental Protection Agency, Washington, DC.
Reviewed 5 August 2009
The release of America's spy satellite images of Arctic sea ice provides unexpected, dramatic new evidence about the dangers of global warming.
These visions of dwindling ice cover confirm that changes in climate in the planet's high latitudes are progressing much faster than originally expected. And what happens there is bound to have an impact elsewhere on our overheating world, in particular to its rising sea levels.
It is not the actual loss of Arctic sea ice that is the danger, of course. Its melting will add nothing, directly, to rises in sea levels. But its dwindling will almost certainly have a profound knock-on effect - mainly on the great ice sheets that cover Greenland and Antarctica. Without sea ice to prop them up at their edges, these sheets will break apart at faster and faster rates and tip more and more ice into the oceans. And once changes have been triggered at their edges, these will be transmitted into the hearts of these great glaciers at remarkably fast rates, scientists predict.
Climate Change contained little input from melting ice sheets in its estimates and concluded, instead, that sea-level rises would be constrained to around 20 to 60 centimetres by the end of the century.
And here lies the threat to Earth. The destruction of the ice sheets of Antarctica and Greenland will feed vast amounts of meltwater into the oceans, far more than has been calculated until very recently. For example, the last report of the Intergovernmental Panel on
That figure now looks uncomfortably optimistic and current estimates put the likely rise at one metre or more by 2100 - a figure backed by the US Geological Survey, which this year warned that rises could reach as much as 1.5 metres. As a result, low-lying areas, including Bangladesh, Florida, the Maldives and the Netherlands, will undergo catastrophic flooding, while in Britain large areas of the Norfolk Broads and the Thames estuary could disappear. In addition, cities including London, Hull and Portsmouth will need new flood defences.
And that is just the beginning. No matter what we do about carbon dioxide emissions - the key cause of this heating and melting - the world will continue to warm and its sea levels to rise beyond 2100. Reversing global warming will be a very long process.
However, we have, if nothing else, been warned!
Tuesday, August 04, 2009
typical tidal conditions . the bayarc project
image courtesy SOM
the san francisco bay conservation and development commission (BCDC) recently hosted an international architecture competition for ideas responding to sea levels rising in san francisco bay and beyond. International firm SOM design was one of the six winners of the rising tide competition.
The bayarc is a minimal, lightweight and environmentally sensitive system designed to protect the san francisco bay area from periodic high water levels associated with sea level rise.
It operates on organic principles of buoyancy and the structural efficiency associated with net membranes and tension. it is a concept that has the potential to eliminate billions of dollars in permanent levees and localized bay area flood protection without compromising the bay's system of ecology and commerce.
flood threat conditions
image courtesy SOM
The objective of the bayarc is to prevent the peak of extreme tide events while maintaining a natural tidal exchange between the ocean and the bay.
The bayarc consists of a submerged, cable reinforced membrane anchored to the seabed that utilizes a bladder embedded in a tensile leading edge fastened to structural pylons at the water's edge. when deployed the bayarc floats to the surface and its tensile membrane creates a barrier stretching from the water's edge to the sea floor. The top cable of the bayarc is connected to anchors on each side of the golden gate bridge
holding the membrane in place. a small amount of tidal or wave energy is captured by flotation devices at each anchor. this energy is used to compress air over time and is released quickly when the bayarc is deployed. the principle forces on the membrane result from drag during deployment as well as the hydrostatic imbalance due to the differential
water level between the ocean and bay. the resulting gentle arc is a direct consequence of these forces. the arc's curvature in plan directly echoes the arc of the golden gate bridge's primary cables. the curvature is derived from the bay's depth the arc's material properties and span.
flood threat conditions - cut away view
image courtesy SOM
l: the golden gate during typical condition r: cross section through golden gate while deployed
image courtesy SOM
tensile membrane stress diagram showing relatively modest stress levels; greatest at center and least at ends
image courtesy SOM
When the peak tide is projected to rise above a threat level, the bayarc is deployed. It remains deployed only until the high tide peak has passed 'shaving off' the peak into the bay. As the falling ocean tide approaches the bay, the bayarc drops and rest on the sea floor as the currents begin to reverse flow. as noted below projections for sea level rise by 2050 would require deployment for only a few house per day and only a few times per year.
Monday, August 03, 2009
From: Environmental Expert
Jul. 31, 2009
The West Antarctic Ice Sheet (WAIS) is vulnerable to even moderate climate change and could collapse rapidly, pushing up sea levels around the world. A new study concludes that the global sea level rise (SLR) from the collapse of the WAIS will not be as high as predicted by previous studies, but still substantial at around 3.3 metres on average.
Previous studies have suggested that if the WAIS was to completely collapse, there would be an SLR of 5 to 6 metres, distributed equally across all regions of the world. However, these studies did not assess how much of the WAIS is unstable and therefore which parts of it are more susceptible to collapse. In addition, most of these studies did not consider how SLR might vary across the world's oceans.
Instead of assuming a complete disintegration of the whole WAIS, the researchers used models, based on glaciological theory, to simulate how it would respond if floating ice shelves which fringe the WAIS broke free. Although they cannot predict when it will collapse, they reassessed the potential volume of ice that could melt and the possible global and regional sea levels rises that would occur.
Ice sheets and glaciers on land naturally flow downwards under the enormous weight of accumulated ice. Those that reach the sea become ice shelves that float on the water. These floating ice shelves exert a backward pressure on the remaining ice sheets which block their downward flow. If warmer ocean temperatures and/or air temperatures disintegrate the ice shelves rapidly, causing them to break free, the ice sheets will be able to move considerably faster.
Much of the WAIS sits on a layer of rock that is below sea level (the marine portion). There are also extensive areas of the WAIS on land. However, slopes on the land, together with the marine portion, cause instability. If the adjacent ice shelves disappear through the effects of a warming climate, parts of the WAIS would accelerate towards the ocean.
The researchers' results suggest that the global sea-level changes would not be equal across the world. The redistribution of the melting ice in the oceans would cause a complex regional pattern of SLR. The highest levels are most likely occur in the Indian Ocean and in a band around 40 degrees North, affecting the Pacific and Atlantic coasts of the United States. This threatens cities including New York, Washington D.C. and San Francisco.
On top of the changes predicted by this study could be the effects of melting in other regions including Greenland and mountain glaciers, also susceptible to a warming climate.