The risk of sea level rise

Abstract

The United Nations Framework Convention on Climate Change requires nations to implement measures for adapting to rising sea level and other effects of changing climate. To decide upon an appropriate response, coastal planners and engineers must weigh the cost of these measures against the likely cost of failing to prepare, which depends on the probability of the sea rising a particular amount.This study estimates such a probability distribution, using models employed by previous assessments, as well as the subjective assessments of twenty climate and glaciology reviewers about the values of particular model coefficients. The reviewer assumptions imply a 50 percent chance that the average global temperature will rise 2 ~ as well as a 5 percent chance that temperatures will rise 4.7 ~ by 2100. The resulting impact of climate change on sea level has a 50 percent chance of exceeding 34 cm and a 1% chance of exceeding one meter by the year 2100, as well as a 3 percent chance of a 2 meter rise and a 1 percent chance of a 4 meter rise by the year 2200.The models and assumptions employed by this study suggest that greenhouse gases have contributed 0.5 mm/yr to sea level over the last century. Tidal gauges suggest that sea level is rising about 1.8 mm/yr worldwide, and 2.5-3.0 mm/yr along most of the U.S. Coast. It is reasonable to expect that sea level in most locations will continue to rise more rapidly than the contribution from climate change alone.We provide a set of 'normalized' projections which express the extent to which climate change is likely to accelerate the rate of sea level rise. Those projections suggest that there is a 65 percent chance that sea level will rise 1 mm/yr more rapidly in the next 30 years than it has been rising in the last century. Assuming that nonclimatic factors do not change, there is a 50 percent chance that global sea level will rise 45 cm, and a 1 percent chance of a 112 cm rise by the year 2100; the corresponding estimates for New York City are 55 and 122 cm.Climate change impact assessments concerning agriculture, forests, water resources, and other noncoastal resources should also employ probability-based projections of regional climate change. Results from general circulation models usually provide neither the most likely scenario nor the full range of possible outcomes; probabilistic projections do convey this information. Moreover, probabilistic projections can make use of all the available knowledge, including the views of skeptics; the opinions of those who study ice cores, fossils, and other empirical evidence; and the insights of climate modelers, which may be as useful as the model results themselves.8 As a practical matter, our own specification would have less credibility because one of us had spent over a decade advocating strategies for adapting to sea level rise (see e.g. Titus, 1984Titus, , 1991Titus, , 1994. Moreover, this approach could help future efforts by motivating glaciologists to think probabilistically about the processes they study.9 This paper follows th...

Climate change impacts on U.S. Coastal and Marine Ecosystems

“…Model averages range more narrowly from 31 to 49 cm. These projections are broadly consistent with previous studies (IPCC 1996;Titus and Narayanan 1996;Wigley 1999) and the Canadian and Hadley models (Boesch et al 2000;NAST 2001). Even if greenhouse gas emissions are stabilized, the rate of sea-level rise will likely continue to increase beyond 2100 because of the time it takes for oceans and ice sheets to approach equilibrium conditions with the atmosphere.…”

Temperature Mediated Moose Survival in Northeastern Minnesota

“…In contrast to the uncertainty associated with estimates of precipitation and temperature change, there is a greater capacity for estimating sea level rise and anticipating its expected impacts on fisheries. There is some certainty to the estimated current and future rate and magnitude of sea level change (Douglas 1991;Titus and Narayanan, 1995), and the importance of sea level to some critical estuarine fisheries (e.g., shrimp) is at least partially understood. For example, the world-wide catch of shrimp is directly related to the acreage of wetland nursery habitat (Turner, 1977(Turner, , 1992.…”

Estimación del comportamiento futuro del nivel del mar en las Islas Canarias a partir del análisis de registros recientes

“…Metodológicamente, se ha realizado una aproximación a la predicción de las expectativas de cambio local, que en publicaciones anteriores se han basado fundamentalmente i) en el uso de expectativas globales (Hallegate et al, 2011, Timmerman et al, 2010, ii) en aproximaciones cuaternaristas a los análisis de antiguos niveles del mar (Lambeck et al, 2011), o iii) en menor medida, en la estimación y comparación de tasas globales con las registradas localmente (Titus y Narayanan, 1995, Woodworth, 1999, Fraile y Ojeda, 2012, Sallenger et al, 2012, aunque empleando métodos de mayor exigencia en los parámetros de los datos de entrada para realizar el análisis estadístico.…”

“…Esta aproximación lleva a contar doblemente cualquier parte de la tendencia histó-rica causada por movimientos eustáticos (Titus y Narayanan, 1995).…”