GLOBAL ESTIMATES OF THE IMPACT OF A COLLAPSE OF THE WEST ANTARCTIC ICE SHEET: AN APPLICATION OF FUND

The threat of an abrupt and extreme rise in sea level is widely discussed in the media, but little understood in practise, including the likely impacts of such a rise. This paper explores for the first time the global impacts of extreme sea-level rise, triggered by a hypothetical collapse of the West Antarctic Ice Sheet (WAIS). As the potential contributions remain uncertain, a wide range of scenarios are explored: WAIS contributions to sea-level rise of between 0.5m/century up to 5m/century. Together with other business-as-usual sea-level contributions, in the worst case this gives an approximately 6-m rise of global-mean sea level from 2030 to 2130. Global exposure to extreme sea-level rise is significant: roughly 400 million people (or about 8% of global population) are threatened by a 5-m rise in sea level, just based on 1995 data. The coastal module within the FUND model is tuned with global data on coastal zone characteristics concerning population, land areas and land use, and then used for impact analysis under the extreme sea-level rise scenarios. The model considers the interaction of (dry)land loss, wetland loss, protection costs and human displacement, assuming perfect adaptation based on cost-benefit analysis. Unlike earlier analyses, response costs are represented in a non-linear manner, including a sensitivity analysis based on response costs. It is found that much of the world’s coast would be abandoned given these extreme scenarios, although according to the global model, significant lengths of the world’s coast are worth defending even in the most extreme case. Hence, this suggests that actual population displacement would be a small fraction of the potential population displacement. This result is consistent with the present distribution of coastal population, which is heavily concentrated in specific areas. Hence a partial defence can protect most of the world’s coastal population. However, protection costs rise substantially diverting large amounts of investment from other sectors, and large areas of (dry)land and coastal wetlands are still predicted to be lost. While some observations of response to abrupt relative sea-level rise due to subsidence support the global model results, detailed case studies of the WAIS collapse in the Netherlands, Thames Estuary and the Rhone delta suggest a greater potential for abandonment than shown by the global model. This probably reflects a range of issues, including: (1) economic criteria such as the cost-benefit ratio is not the only factor which drives response decisions, with wider perceptions of risk driving the actual response; (2) the inefficiencies of adaptation in the real world, including indecision and competition for limited resources; and (3) the possible loss of confidence under the scenario of abrupt climate change. Collectively, these results illustrate an area where there are potential limits to adaptation, even when economic analysis suggests that adaptation will occur. The significant impacts found in the global model together with the potential for greater impacts as found in the detailed case studies shows that the response to abrupt sea-level rise is worthy of further research, including exploring the differing impact results by scale.Abrupt climate change, sea-level rise, coastal impacts, adaptation, adaptation limits

Worst Case Scenario and Stakeholder Group Decision: A 5-6 Meter Sea Level Rise in the Rhone Delta, France

Risk policy and public attitudes appear disconnected from research predicting warmer climate partially due to human activity. To step out of this stalled situation, a worst case scenario of a 5-6m sea level rise (SLR) induced by the collapse of the WAIS and occurring during the period 2030-2130 is constructed and applied to the Rhone delta. Physical and socio-economic scenarios developed with data from the Rhone delta context are developed and submitted to stakeholders for a day-long workshop. Group process analysis shows a high level of trust and cooperation mobilized to face the 5-6m SLR issue, despite potentially diverging interests. Two sets of recommendations stem from the scenario workshop. A conservative "wait and see" option is decided when the risk of the WAIS collapse is announced in 2030. After WAIS collapse generates an effective 1m SLR rise by 2050, decisions are taken for total retreat and rendering of the Rhone delta to its hydrological function. The transposition of these results into present times policy decisions could be considered. The methodology developed here could be applied to other risk objects and situations, and serve for policy exercises and crisis prevention.Sea level rise, France, Camargue, scenario, extreme climate, stakeholder workshop

A Mediterranean coastal database for assessing the impacts of sea-level rise and associated hazards

We have developed a new coastal database for the Mediterranean basin that is intended for coastal impact and adaptation assessment to sea-level rise and associated hazards on a regional scale. The data structure of the database relies on a linear representation of the coast with associated spatial assessment units. Using information on coastal morphology, human settlements and administrative boundaries, we have divided the Mediterranean coast into 13 900 coastal assessment units. To these units we have spatially attributed 160 parameters on the characteristics of the natural and socio-economic subsystems, such as extreme sea levels, vertical land movement and number of people exposed to sea-level rise and extreme sea levels. The database contains information on current conditions and on plausible future changes that are essential drivers for future impacts, such as sea-level rise rates and socio-economic development. Besides its intended use in risk and impact assessment, we anticipate that the Mediterranean Coastal Database (MCD) constitutes a useful source of information for a wide range of coastal applications.Peer ReviewedPostprint (published version

Regionalisation of population growth projections in coastal exposure analysis

Large-area coastal exposure and impact analysis has focussed on using sea-level rise (SLR) scenarios and has placed little emphasis on ocioeconomic scenarios, while neglecting spatial variations of population dynamics. We use the Dynamic Interactive Vulnerability Assessment (DIVA) Framework to assess the population exposed to 1 in 100-year coastal flood events under different population scenarios, that are onsistent with the shared socioeconomic pathways (SSPs); and different SLR scenarios, derived from the representative concentration pathways (RCPs); and analyse the effect of accounting for regionalised population dynamics on population exposure until 2100. In a reference approach, we use homogeneous population growth on national level. In the regionalisation approaches, we test existing spatially explicit projections that also account for urbanisation, coastal migration and urban sprawl. Our results show that projected global exposure in 2100 ranges from 100 million to 260 million, depending on the combination of SLR and population scenarios and method used for regionalising the population projections. The assessed exposure based on the regionalised approaches is higher than that derived from the reference approach by up to 60 million people (39%). Accounting for urbanisation and coastal migration leads to an increase in exposure, whereas considering urban sprawl leads to lower exposure. Differences between the reference and the regionalised approaches increase with higher SLR. The regionalised approaches show highest exposure under SSP5 over most of the twenty-first century, although total population in SP5 is the second lowest overall. All methods project the largest absolute growth in exposure for Asia and relative growth for Africa

Plausible responses to the threat of rapid sea-level rise for the Thames Estuary

This paper considers the perceptions and responses of selected stakeholders to a scenarion of rapid rise in sea-level due to the collapse of the West Antarctic ice sheet, which could produce a global rise in sea-level of 5 to 6 metres. Through a process of dialogue involving one-to one interviews and a one-day policy exercise, we addressed influences on decision-making when information is uncertain and our ability to plan, prepare for and implement effective ways of coping with this extreme scenario. Through these interactions we hoped to uncover plausible responses to the scenario and identify potential weaknesses in our current flood management approaches to dealing with such an occurrence. By undertaking this exploratory exercise we hoped to find out whether this was a feasible way to deal with such a low probability but high consequence scenario. It was the process of finding a solution that interested us rather than the technical merits of one solution over another. We were not intending to produce definitive set of recommendations on how to respond but to gain insights into the process of making a decision, specifically what influences it and what assumptions are made.Sea level rise, London

Procesos modeladores en los acantilados de Las Grutas, provincia de Río Negro

Fil: Fucks, Enrique. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Análisis de Tritio y Radiocarbono; ArgentinaFil: Schnack, Enrique J.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Oceanografía Costera y Estuarios; ArgentinaFil: Scalice, Armando. Consultor independiente; ArgentinaFil: Kai, Ahrendt. Albrechts Universtitat zue Kiel. Geographisches Institut Christian; AlemaniaFil: Vafeidis, Nassos. Albrechts Universtitat zue Kiel. Geographisches Institut Christian; AlemaniaFil: Sterr, Horst. Albrechts Universtitat zue Kiel. Geographisches Institut Christian; Alemani

New expert- based coastal classification: a GIS tool to compare and analyze coastal regions

A coastline is the area where interaction of the sea and land processes occurs. Coastal areas are very high- dynamic regions, continuously affected and permanently formed by littoral geomorphologic processes (Bird 2008). The configuration of a coast is associated with variou s factors, such as the geological setting, s ub strate -lithology, ecosystem characteristics, regional climate, wave and tidal regimes, human development and near shore infrastructure. To conduct a coastal classification in broad se n se i s a fairly com plex task, depending on the objective of the work. Many di.fferent concepts h ave been applied to coasts in attempts to characterize dominant features in terms of physical or biological propertie s, modes of evolution, geographic occurrence, among others (Finkl 2004). Also, the need for a better coastal management dueto the wodd-wide human pressures on the coastal zone and the resulting vulnerability when erosion processes and human activity come into conflict, motivated the development of coastal classification criteria that fit di.fferent purposes (Finkl 2004, I h1 et al 2006, Appelq ui st 2013, Appelq uist y B alstr0m 2014 ). Sorne of the ear lier classification approaches were broad in scope but lacked important details while other specialized systems were topicallytoo focused. As a result of more com prehensive studies of coasts and the increasing availability of digital information, such as Geographic Information System (GIS) frameworks, integrated and systematics approaches to coastal cla ssifi cation are now the preferred options (Finkl 2004 y Scheffers et al 2012). Present-day managem e nt demands require problem solutions, which ovedook and integrate the marine, littoral and terrestrial sphere of the coastal zone

Faint Infrared Flares from the Microquasar GRS 1915+105

We present simultaneous infrared and X-ray observations of the Galactic microquasar GRS 1915+105 using the Palomar 5-m telescope and Rossi X-ray Timing Explorer on July 10, 1998 UT. Over the course of 5 hours, we observed 6 faint infrared (IR) flares with peak amplitudes of $\sim 0.3-0.6$ mJy and durations of $\sim 500-600$ seconds. These flares are associated with X-ray soft-dip/soft-flare cycles, as opposed to the brighter IR flares associated with X-ray hard-dip/soft-flare cycles seen in August 1997 by Eikenberry et al. (1998). Interestingly, the IR flares begin {\it before} the X-ray oscillations, implying an ``outside-in'' origin of the IR/X-ray cycle. We also show that the quasi-steady IR excess in August 1997 is due to the pile-up of similar faint flares. We discuss the implications of this flaring behavior for understanding jet formation in microquasars.Comment: 10 pages, 4 figures Accepted for publication in ApJ Letter

Procesos modeladores en los acantilados de Las Grutas, provincia de Río Negro

Los acantilados desarrollados en la localidad de Las Grutas, al N del golfo San Matías, representan uno de los ambientes más particulares del litoral argentino. Los factores que han condicionado su particular evolución están relacionados con los procesos litorales, la meteorización, la litología, cambios del nivel del mar, escurrimientos subterráneos y superficiales y remoción en masa, entre los más importantes. Si bien existe una percepción de parte de la población de que los mismos están retrocediendo de manera alarmante, no se han observado procesos erosivos importantes que sustenten estas apreciaciones. Se considera que las condiciones litológicas heterogéneas del frente acantilado, han condicionado el escurrimiento subterráneo, haciendo más propensos los sectores finamente estratificados a la erosión, encontrando el mar una situación más favorable para los procesos mecánicos e hidráulicos. Asimismo, se considera que el sector de los acantilados donde se desarrollan las cavernas más prominentes, constituye uno de los sectores costeros mas estables, reflejado en la presencia no solo de las cavernas, sino también en la saliente que la costa forma en este lugar, el que se asocia a escasos procesos de agrietamiento de todo el sistema, producto de escasos cambios en la humectación y secado. Asimismo, la depresión topográfica que se manifiesta en el sector central, produce el accionar de las olas sobre los estratos más heterogéneos de manera recurrente, llevando a la formación de la gran cantidad de cavernas desarrolladas casi con exclusividad en este sector.The cliffs developed in the town of Las Grutas, at the northen part of San Matías Gulf, represent one of the most unique environments of the Argentine coast. The factors that have conditioned their particular evolution are related to the littoral action, weathering, lithology, changes in sea level, underground and surface runoff and landslides, among the most important. There is a perception on the part of the population that they are receding alarmingly, it has not been found major erosion to sustain those opinions. It is considered that the heterogeneous geological characteristics of the cliff front have conditioned the underground runoff, making the areas finely stratified more prone to erosion, finding the sea a more favorable mechanical and hydraulic processes situation. It is also considered that the cliff sector, where the most prominent caves are developed, is one of the most stable coastal areas, evidenced by the presence not only of the caves, but also in the prominent exposure of the coastal forms here, which is associated with low cracking processes of the entire system as a result of little change in the wetting and drying. Also, a lower topographical situation determines the recurrence of wave action on heterogeneous strata, leading this cliff sector to the formation of the caves

Shifting perspectives on coastal impacts and adaptation

The Intergovernmental Panel on Climate Change reports reflect evolving attitudes in adapting to sea-level rise by taking a systems approach and recognizing that multiple responses exist to achieve a less hazardous coast.info:eu-repo/semantics/publishedVersio