Our Common Future Under Climate Change

International Scientific Conference 7-10 JULY 2015 Paris, France

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Wednesday 8 July - 17:30-19:00 UPMC Jussieu - Amphi Herpin

2210 - Coastal Impacts of Climate Change

Parallel Session

Lead Convener(s): V. Duvat-Magnan (UMR LIENSs 7266 University of La Rochelle - National Centre for Scientific Research (CNRS), La Rochelle, France)

Convener(s): F. Fromard (University of Toulouse-CNRS, Toulouse, France), G. Le Cozannet (BRGM, Orléans, France)

17:30

Towards a coastal vulnerability typology for small islands: Assessing diversity and similarity via a common framework

R. Mclean (University of New South Wales, Canberra, BC ACT, Australia)

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Towards a coastal vulnerability typology for small islands: Assessing diversity and similarity via a common framework

R. Mclean (1)
(1) University of New South Wales, School of physical, environmental and mathematical sciences, Canberra, BC ACT, Australia

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The Small Islands chapter of the IPCC AR5 reaffirmed the vulnerability of small islands to climate change threats due to their inherent physical and human characteristics, high exposiure to extreme events, and to the high dependence of island communities and economies on threatened ecosystems such as coral reefs and mangrove forests. It also emphasized that small islands present diverse risk profiles - a point that has not been sufficiently recognized in the literature. The chapter invited the scientific community to include island diversity in future V & A assessments within a consistent methodology approriate at regional, archipelagic and island scales.

Envisaged was the design of a new island typology reflecting both the heterogeneity and homogeneity of islands and island coasts that also included a range of climate-ocean processes and not just sea-level rise. Over the past three decades many coastal vulnerability assessments have been undertaken in the Caribbean, Mediterranean, Indian and Pacific Oceans most of which have applied a predetermined methodology with an emphasis on sectors, e.g. water, human health and agriculture, on certain coastal types, e.g. deltas, mangrove shores and sany beaches, and with an almost singular focus on sea-level rise. None of the assessments have: (1) covered whole regions; (2) dealt with the full range of coastal types on islands; or (3) considered the entire suite of climate-change drivers.

A protoype of a new typology that satisfies these criteria has been developed in the Pacific covering 15 countries and 1532 islands. The objective was to produce a regional coastal vulnerability typology based on the inherent geomorphological characteristics of islands and all relevant climate-ocean processes that drive coastal change. Development of the typology comprised a series of nested scales with increasing spatial and temporal resolution at each step from all islands to a coastal segemnt of a single island. Initially islands were classified into 8 types based on two simple characteristics: lithology (rock type) and maximum elevation. To these attributes were added island area and shape to develop an 'indicative susceptibility'. This index recognized that certain island types are inherently more susceptible (less resistant) to change than others, for example a low elevation sedimentary reef island is more susceptible than a high elevation volcanic rock island. A five-point susceptibility rating was derived for all 1532 islands that included all island types within each country in the region, e.g. the 431 islands in the Solomon Islands.

The second step was to refine the scale from whole-island to coastal-margin with more variables added to the diagnostic criteria, including measures of insularity and proximity to other islands. Further downscaling to coastal compartments with more diagnostic criteria enabled development of higher resolution susceptibility measures. The third step was to identify the key climate and oceanographic drivers of coastal change together with their projected future changes through 2100 based on AR5 and recent Pacific-wide projections of tides, wind and waves, distant-source swell, ENSO, tropical cyclones and sea-level change. Finally, how these processes interact with different island and coastal types in different regions of the Pacific was documented through a 'coastal sensitivity' measure based on island location and projected changes in that part of the Pacific. Sensitivities were calculated for the 1532 islands. Some surprising patterns emerged from these data including the fact that atoll islands do not all fit into the very high sensitivity class but range over moderate, high and very high on a five-point sensitivity scale.

This coastal vulnerability typology developed for small islands in the Pacific provides a consistent and defensible methodology that should: (1) enhance the capacity of decision-makers to take climate risk into coastal adaptation planning and management; (2) enable agencies to invest in targeted and transferable adaptation projects with island partners; and (3) be applicable at all scales from global to local including other small island regions.

 

17:45

Benefits of mitigation of climate change for coastal areas

R. Nicholls (Tyndall Centre for Climate Change Research, Southampton, United Kingdom)

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Benefits of mitigation of climate change for coastal areas

R. Nicholls (1)
(1) Tyndall Centre for Climate Change Research, Southampton, United Kingdom

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18:00

Marine and Coastal Ecosystems: what are the impacts?

L.M. Piedra Castro (Universidad Nacional, Cartago, Costa Rica)

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Marine and Coastal Ecosystems: what are the impacts?

LM. Piedra Castro (1)
(1) Universidad Nacional, Escuela de Ciencias Biológicas, Cartago, Costa Rica

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Coastal areas have traditionally been important to the development of human communities. Those who have exploited ecosystemic resources they provide them. These systems have been overexploited and polluted modified by human activities. Associated with these pressures, climate change may be impacting these ecosystems. The objective of this study was to analyze the factors affecting coastal and marine ecosystems and their conservation. For this analysis, the province of Limon was selected on the Caribbean coast of Costa Rica, including the southern sector. The evaluation was conducted in the communities of Wesfalia, Vizcaya, Cahuita, Puerto Viejo, Manzanillo and Gandoca. For the analysis of the beaches, the width of the beach, vegetation cover, type of dominant roots of vegetation, plant species composition, average height of vegetation and substrate type were evaluated. For evaluation of the reef and seagrass beds community, we use the methodology AGRRA 2.2 modified for depths between 1 and 6 m. In the mangrove, we applied the methodology of using Murdiyarso et al. (2009). NOAA satellite data for sea surface temperature, chlorophyll, precipitation and atmospheric CO2 were used. In the analysis, the Integrated Health Index Reef showed Isla Uvita, Cahuita, Puerto Viejo and Manzanillo have values of 3.7; 2.6; 3.45 and 2.86 respectively. The first and third places have good condition. Meanwhile, the second and fourth showed regular condition. Seagrass beds coverage showed 71.67 ± 10.4, number of offshoots 39.00 ± 77.93 and average heights of 7.00 ± 1.0 for Thalassia testudinium in Uvita Island. In Cahuita and Manzanillo, 2 species were observed (Syringodium filiforme and Thalassia testudinium) with coverage (%), number of offshoots and average heights with lower values than those reported in Uvita Island. In Puerto Viejo, the coverage was negligible. In all areas, small patches were observed connected reefs. For beaches, quality indicators showed that Gandoca and Manzanillo are the most impacted areas. Erosion was 91% and 56% respectively. As for coverage was 95 ± 8.13 and 65 ± 6.6 respectively. The other localities showed regular conditions. Cahuita mangroves and Gandoca were analyzed. The area was 2.85 and 13, 58 ha respectively. The number of species was 7 and 12 respectively. The dominant species Pterocarpus officinalis (16.78%) and Rhizophora mangle (29.45%) respectively. The number of dead trees was 15 and 26 individuals per ha respectively. The densities were of 53 ± 3.26 and 77 ± 9.87 individuals per ha respectively. There is significant difference between the temperature of a surface of the sea between 2001 and 2013 (W = 1.14284E7; p = 0). According to the comparison of medians (Mann-Whitney test) there is a significant difference in the concentration of chlorophyll "a" between 2003 and 2013 (W = 0.86652E7; p <0.05). Increased wave and tide, caused by the increase in sea level and global climate change to produce more intense hurricanes and Norths winds, affecting upper parts of the beach that normally were not affected, being more vulnerable low slope beaches. It is concluded that the composition and structure of the shallow coral community in the 4 locations were evaluated regularly, in the case of Puerto Viejo, right on the Isla Uvita. The most important sites in both species Rhizophora mangle was also found Laguncularia and Avicennia germinans with other associated species. Riverine mangroves are two types during the dry season but a sand bar that prevents water flow is established. For Gandoca is stable as a coastal lagoon and in the case of Cahuita, like a swamp. The conservation status of these systems as ocean acidification that seems to reduce the number of sperm released by corals and agrees that recruitment of larvae and the effect may start slowly or perceived, can be mitigated by the resilience of whose mechanisms of macroevolution system could not hope to provide answers to climate change. The strategies by reduce pressures on the species referred must be reduced the pressure in this ecosystem. In that sense, they must have the flexibility to confront climate change and that seems to be the most recommended practice in marine and coastal areas due to the difficulties of direct management in these areas.  Some actions to mitigate climate variability are rehabilitating habitat mitigation program of coastal erosion control plan and mitigate the impact of lionfish and adaptation measures in management plans for marine turtles.

18:15

Assessing the vulnerability of Air and Sea Ports in Small Islands: Risk Factors and Adaptation Guidance

L. Nurse (University of the West Indies, Bridgetown, Barbados)

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Assessing the vulnerability of Air and Sea Ports in Small Islands: Risk Factors and Adaptation Guidance

L. Nurse (1)
(1) University of the West Indies, CERMES, Faculty of Science and Technology, Bridgetown, Barbados

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Since publication of the IPCC First Assessment in 1990, all subsequent reports have identified key reasons for and drawn global attention to, the vulnerability of small islands to the adverse consequences of climate change, particularly sea level rise. The Summary for Policymakers of the recently released Working Group II Contribution to the Fifth Assessment Report (AR5-SPM-WGII), notes that various forms of disruption in islands and low-lying coastal states due to storm surges, flooding and sea level rise can be expected, with high confidence. Specifically, the AR5 emphasizes the risk of loss and damage to vital living and non-living coastal and marine resources in islands (e.g. beaches, coral reefs, seagrasess, mangrove wetlands) and their associated goods and services. While impact severity will vary within and among regions, the AR5- SPM-WGII projects that some small island states could suffer damages and adaptation costs of ‘several percentage points of GDP’ over the 21st Century and beyond.

 

By virtue of the ‘openness’ of their economies and the consequential reliance on imports and exports to sustain livelihoods, small islands are heavily dependent on the functionality and efficiency of their air and seaports. Unlike many larger continental-scale countries, international trade in SIDS is not facilitated by other transportation media such as road and rail. Between fifty and ninety percent of all food and beverages consumed in SIDS come from external sources, and more than ninety percent of all energy products used in SIDS, including hydrocarbon fuels, are handled through air and sea ports. On average, in excess of seventy-five percent of the consumables that support other sectors pass through these ports of entry. In addition, SIDS earn considerable local and foreign revenues from various port-related activities, including berthing and bunkering, airport landing and maintenance, containerized and other storage charges, waste reception fees and cruise passenger imposts, inter alia. As in other countries, considerable direct and indirect employment is also generated by air and sea ports in SIDS. 

The climate-related risks posed to ports must therefore be of considerable concern to small islands and low-lying coastal states. While an increasing number of vulnerability assessments conducted on islands have evaluated the impacts of climate change and climate variability on coastal infrastructure, few have specifically examined the implications of the threat for ports in these regions. Hence, this work attempts to contribute to filling that gap by focusing on the vulnerability of air and sea ports in SIDS to climate change related impacts. More specifically, the risks posed to port infrastructure by sea level rise and projected changes in the behavior of some hydro-meteorological events will be examined.  Equally, the potential for disruption to critical port-related functions as a consequence of climate change, will also be explored. 

Some guidance on the selection of criteria for evaluating the appropriateness of adaptation responses is offered, which it is hoped would be helpful to port managers and planners in the SIDS regions. In this regard, while the similarities among small islands will help to form a basis for identification of some criteria, the guidance emphasizes that island diversity in its many forms – biogeophysical, economic, socio-cultural and political – helps to shape the risk profile of each country, and should therefore be an important consideration when making adaptation choices, including in the air and sea port sub-sector.

 

Finally, it is cautioned that notwithstanding the uncertainties, delaying adaptation in this crucial sub-sector, the lynch-pin of many island economies, may not be prudent, given the conclusions of the IPCC-AR5. It is suggested that an approach to adaptation which judiciously integrates what is known about the present-day vulnerability of ports with our ‘best understanding’ of future climate risks, would constitute a meaningful risk management strategy for air and sea ports in SIDS.

18:25

Managing increasing risks in coastal cities

S. Hallegatte (Climate Change Group , Washington , United States of America), R. Nicholls (Tyndall Centre for Climate Change Research, Southampton, United Kingdom), J. Corfee-Morlot (OECD, Paris, France), C. Green (None, London, United Kingdom)

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Managing increasing risks in coastal cities

S. Hallegatte (1) ; R. Nicholls (2) ; J. Corfee-Morlot (3) ; C. Green (4)
(1) Climate Change Group , Washington , United States of America; (2) Tyndall Centre for Climate Change Research, Southampton, United Kingdom; (3) OECD, Paris, France; (4) None, London, United Kingdom

Abstract content

Coastal areas are particularly exposed to climate change and sea level rise, and large coastal cities represent hotspots of vulnerability and risk. In particular, coastal protections calibrated for current hazards and environmental conditions can quickly become inappropriate, leading to major increases in risk level: with rapid climate and economic trends, good protections can be more dangerous than helpful, in the absence of continuous adaptation. This presentation illustrates on major coastal cities how risk responds to change in sea level with and without adaptation, and discusses policy implications regarding coastal protection, risk management, and investment needs. A specific focus will be given to the need for comprehensive risk management packages that combine ex ante prevention actions with ex post actions that enhance the ability of the affected cities and people to recover and reconstruct. Finally, implications on poverty and inequality will be discussed, as protection choices will have large distribution and wealth impacts.

18:35

Coastal forested wetlands as affected by sea-level rise and land-use in Caribbean islands: lessons from the past

D. Imbert (UMR ECOFOG/Universty of Antilles, Pointe-à-Pitre, Guadeloupe, France), D. Galop (UMR GEODE, Toulouse, France), A. Lenoble (UMR PACEA, Pessac, France), C. Stouvenot (UMR ArchAm, Basse-Terre, France)

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Coastal forested wetlands as affected by sea-level rise and land-use in Caribbean islands: lessons from the past

D. Imbert (1) ; D. Galop (2) ; A. Lenoble (3) ; C. Stouvenot (4)
(1) UMR ECOFOG/Universty of Antilles, Pointe-à-Pitre, Guadeloupe, France; (2) UMR GEODE, Cnrs, Toulouse, France; (3) UMR PACEA, Cnrs, Pessac, France; (4) UMR ArchAm, Service régional de l'archéologie, Basse-Terre, France

Abstract content

Tropical coastal plains and estuaries have developed large forested wetlands during the present postglacial transgression. In the Caribbean islands, such wetlands are subjected to specific hydrological characteristics due to small tidal range, seasonal rainfall, low mineral siltation, and frequent powerful hurricanes.  In this context, a large amount of the atmospheric carbon fixed annually by the vegetation is stored underwater and form peat deposits several meters depth.  As a result, these autochthonous organic sediments act as invaluable paleoecological archives of past climatic changes and catastrophic events that have affected coastal ecosystems over times. Recent and ongoing research conducted in the Lesser Antilles is presented to document this issue and put into a broader perspective the expected changes for the near future. In Guadeloupe, peat sediments over 10 meters depth have accumulated at an average rate of 1 mm/year during the last 3000 years, with no significant variation of the coastline. However, recent data indicate that before 4000 years B.P. faster sea-level rise (≥ 1,5 mm/year) may have cause dramatic coastline retreat.  In the meantime, periodic climatic changes (dryer/wetter) have caused functional and structural changes whereas human activities inside these wetlands contributed to reduce forested areas (especially swamp forests) and, comparatively, promote herbaceous vegetation. Current trends in sea-level rise indicate that compensatory threshold of soil-level rise is being exceeded; as a result, landward intrusion of saltwater wedge is expected to occur farther and more frequently, especially under a forecasted dryer climate. Conversely, endangered freshwater ecosystems like the Pterocarpus swamp forest could be at risk of extinction because of the limited possibilities of upward migration, due to land use and inland steep topography.