A Regional Review of Marine and Coastal Impacts of Climate Change on the ROPME Sea Area

The Regional Organization for the Protection of the Marine Environment (ROPME) Sea Area (RSA) in the northern Indian Ocean, which comprises the Gulf, the Gulf of Oman and the northern Arabian Sea, already experiences naturally extreme environmental conditions and incorporates one of the world’s warmest seas. There is growing evidence that climate change is already affecting the environmental conditions of the RSA, in areas including sea temperature, salinity, dissolved oxygen, pH, and sea level, which are set to continue changing over time. The cumulative impacts of these changes on coastal and marine ecosystems and dependent societies are less well documented, but are likely to be significant, especially in the context of other human stressors. This review represents the first regional synthesis of observed and predicted climate change impacts on marine and coastal ecosystems across the ROPME Sea Area and their implications for dependent societies. Climate-driven ecological changes include loss of coral reefs due to bleaching and the decline of fish populations, while socio-economic impacts include physical impacts from sea-level rise and cyclones, risk to commercial wild capture fisheries, disruption to desalination systems and loss of tourism. The compilation of this review is aimed to support the development of targeted adaptation actions and to direct future research within the RSA.

On the influence of ENSO complexity on Pan-Pacific coastal wave extremes

Wind-generated waves are dominant drivers of coastal dynamics and vulnerability, which have considerable impacts on littoral ecosystems and socioeconomic activities. It is therefore paramount to improve coastal hazards predictions through the better understanding of connections between wave activity and climate variability. In the Pacific, the dominant climate mode is El Niño Southern Oscillation (ENSO), which has known a renaissance of scientific interest leading to great theoretical advances in the past decade. Yet studies on ENSO’s coastal impacts still rely on the oversimplified picture of the canonical dipole across the Pacific. Here, we consider the full ENSO variety to delineate its essential teleconnection pathways to tropical and extratropical storminess. These robust seasonally modulated relationships allow us to develop a mathematical model of coastal wave modulation essentially driven by ENSO’s complex temporal and spatial behavior. Accounting for this nonlinear climate control on Pan-Pacific wave activity leads to a much better characterization of waves’ seasonal to interannual variability (+25% in explained variance) and intensity of extremes (+60% for strong ENSO events), therefore paving the way for significantly more accurate forecasts than formerly possible with the previous baseline understanding of ENSO’s influence on coastal hazards.

Quantifying ambiguity in sea-level projections

<p>Coastal impacts of climate change and the related mitigation and adaptation needs requires assessments of future sea-level changes. Following a common practice in coastal engineering, probabilistic sea-level projections have been proposed for at least 20 years. This requires a probability model to represent the uncertainties of future sea-level rise, which is not achievable because potential ice sheets mass losses remain poorly understood given the knowledge available today. Here, we apply the principles of extra-probabilistic theories of uncertainties to generate global and regional sea-level projections based on uncertain components. This approach assigns an imprecision to a probabilistic measure, in order to quantify lack of knowledge pertaining to probabilistic projections. This can serve to understand, analyze and communicate uncertainties due to the coexistence of different processes contributing to future sea-level rise, including ice-sheets. We show that the knowledge gained since the 5th Assessment report of the IPCC allows better quantification of how global and regional sea-level rise uncertainties can be reduced with lower greenhouse gas emissions. Furthermore, Europe and Northern America are among those profiting most from a policy limiting climate change to RCP 2.6 versus RCP 4.5 in terms of reducing uncertainties of sea-level rise.</p>

Identifying oceanographic conditions conducive to coastal impacts on temperate open coastal beaches and the importance of empirical impact data

Warnings issued by meteorological or oceanographic agencies are a common means of allowing people to prepare for likely impactful events. Quantifying the relationships between ocean conditions and coastal impacts is crucial for developing operational coastal hazard warnings. Existing studies have largely omitted empirical data, relying on modelling to estimate total water levels and impact potentials. It is well documented that site-specific conditions influence local morphodynamics and as such, detailed data related to the physical environment is a necessary component of these existing approaches. The capacity to collect this data is not always available and there is a need for the inclusion of physical impact events to properly quantify the effects of natural hazards and identify the conditions that they are likely to occur. We propose an alternative empirically-based framework for isolating oceanic conditions that are conducive to impact along open coasts, using two case studies from Victoria, southeast Australia: Port Fairy and Inverloch. Oceanic conditions were defined using data obtained from a WAVEWATCH III (WW3) model hindcast, assessed against newly-installed wave buoys, which evidenced variation in mean conditions between the two sites. We coupled impact-based data derived from citizen-science and social media to modelled and observational data, to identify the oceanic conditions that led to these impacts. We found heterogeneity in the response of the case study locations to deviations from the local mean wave characteristics and still water levels. This paper demonstrates a framework through which impact-based thresholds for erosion could be developed for management applications and early-warning systems.

RECENT EXTREME TROPICAL CYCLONE DAMAGE

In this talk, I will review and discuss coastal impacts from recent land-falling cyclones.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/uR3nuOew1W4

CLIMATE CHANGE VULNERABILITY ASSESSMENT FOR AMERICAN SAMOA: FOCUS ON TRANSPORTATION INFRASTRUCTURE

Essential transportation infrastructure around the globe will be increasingly compromised by interrelated climate change impacts. Due to geographic isolation and limited natural resources, the economy and security of many Pacific territories and nations, including American Samoa, depend heavily on the resilience of these transportation infrastructure systems. Of particular relevance are the coastal impacts of climate changes such as sea level rise and storm surges which will threaten transportation infrastructure including both temporary and long-term flooding of airports, ports and harbors, and roads which are vital lifelines for trans-Pacific, interisland, and intra-island commerce and community services. The majority of the transportation assets in American Samoa are along a narrow coastal plain backed by steep topography, precluding relocation or retreat in response to increased coastal flooding accompanying a changing climate.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/k-qJPMVwvVc

Coastal Impacts, Recovery, and Resilience Post-Hurricane Sandy in the Northeastern US

Post-Hurricane Sandy research has improved our understanding of coastal resilience during major storm events, accelerated sea level rise, and other climate-related factors, helping to enhance science-based decision-making, restoration, and management of coastal systems. The central question this special section examines is: “looking across the breadth of research, natural resource management actions and restoration projects post-Hurricane Sandy, what can we say about coastal impact, recovery, and resilience to prepare for increasing impacts of future storms?” These five studies, along with lessons from other published and unpublished research, advance our understanding beyond just the documentation of hurricane impacts but also highlights both natural and managed recovery, thereby advancing the developing field of coastal resilience.