Global Average Sea Level Research Articles

Ice-sheet contributions to future sea-level change

Accurate simulation of ice-sheet surface mass balance requires higher spatial resolution than is afforded by typical atmosphere-ocean general circulation models (AOGCMs), owing, in particular, to the need to resolve the narrow and steep margins where the majority of precipitation and ablation occurs. We have developed a method for calculating mass-balance changes by combining ice-sheet average time-series from AOGCM projections for future centuries, both with information from high-resolution climate models run for short periods and with a 20km ice-sheet mass-balance model. Antarctica contributes negatively to sea level on account of increased accumulation, while Greenland contributes positively because ablation increases more rapidly. The uncertainty in the results is about 20% for Antarctica and 35% for Greenland. Changes in ice-sheet topography and dynamics are not included, but we discuss their possible effects. For an annual- and area-average warming exceeding 4.5+/-0.9K in Greenland and 3.1+/-0.8K in the global average, the net surface mass balance of the Greenland ice sheet becomes negative, in which case it is likely that the ice sheet would eventually be eliminated, raising global-average sea level by 7m.

Potential effects of sea level rise on the terrestrial habitats of endangered and endemic megafauna in the Northwestern Hawaiian Islands

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 2:21-30 (2006) - doi:10.3354/esr002021 Potential effects of sea level rise on the terrestrial habitats of endangered and endemic megafauna in the Northwestern Hawaiian Islands Jason D. Baker1,2,*, Charles L. Littnan1, David W. Johnston3 1Pacific Islands Fisheries Science Center, National Marine Fisheries Service, NOAA, 2570 Dole Street, Honolulu, Hawaii 96822, USA 2University of Aberdeen, School of Biological Sciences, Lighthouse Field Station, George Street, Cromarty, Ross-shire IV11 8YJ, UK 3Joint Institute for Marine and Atmospheric Research, 1000 Pope Road, Honolulu, Hawaii 96822, USA *Email: jason.baker@noaa.gov ABSTRACT: Climate models predict that global average sea level may rise considerably this century, potentially affecting species that rely on coastal habitat. The Northwestern Hawaiian Islands (NWHI) have high conservation value due to their concentration of endemic, endangered and threatened species, and large numbers of nesting seabirds. Most of these islands are low-lying and therefore potentially vulnerable to increases in global average sea level. We explored the potential for habitat loss in the NWHI by creating topographic models of several islands and evaluating the potential effects of sea level rise by 2100 under a range of basic passive flooding scenarios. Projected terrestrial habitat loss varied greatly among the islands examined: 3 to 65% under a median scenario (48 cm rise), and 5 to 75% under the maximum scenario (88 cm rise). Spring tides would probably periodically inundate all land below 89 cm (median scenario) and 129 cm (maximum scenario) in elevation. Sea level is expected to continue increasing after 2100, which would have greater impact on atolls such as French Frigate Shoals and Pearl and Hermes Reef, where virtually all land is less than 2 m above sea level. Higher elevation islands such as Lisianski, Laysan, Necker, and Nihoa may provide longer-term refuges for species. The effects of habitat loss on NWHI biota are difficult to predict, but may be greatest for endangered Hawaiian monk seals, threatened Hawaiian green sea turtles, and the endangered Laysan finch at Pearl and Hermes Reef. This study marks the first effort to detail the topography and evaluate sea level rise effects on NWHI species. KEY WORDS: Sea level rise · Habitat loss · Northwestern Hawaiian Islands · Hawaiian monk seal · Green sea turtle · Laysan finch Full text in pdf format PreviousNextExport citation Mail this link - Contents Mailing Lists - RSS Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 2. Online publication date: May 24, 2006 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2006 Inter-Research.

Elimination of the Greenland Ice Sheet in a High CO2 Climate

Abstract Projections of future global sea level depend on reliable estimates of changes in the size of polar ice sheets. Calculating this directly from global general circulation models (GCMs) is unreliable because the coarse resolution of 100 km or more is unable to capture narrow ablation zones, and ice dynamics is not usually taken into account in GCMs. To overcome these problems a high-resolution (20 km) dynamic ice sheet model has been coupled to the third Hadley Centre Coupled Ocean–Atmosphere GCM (HadCM3). A novel feature is the use of two-way coupling, so that climate changes in the GCM drive ice mass changes in the ice sheet model that, in turn, can alter the future climate through changes in orography, surface albedo, and freshwater input to the model ocean. At the start of the main experiment the atmospheric carbon dioxide concentration was increased to 4 times the preindustrial level and held constant for 3000 yr. By the end of this period the Greenland ice sheet is almost completely ablated and has made a direct contribution of approximately 7 m to global average sea level, causing a peak rate of sea level rise of 5 mm yr−1 early in the simulation. The effect of ice sheet depletion on global and regional climate has been examined and it was found that apart from the sea level rise, the long-term effect on global climate is small. However, there are some significant regional climate changes that appear to have reduced the rate at which the ice sheet ablates.

Coastal and global averaged sea level rise for 1950 to 2000

We compare estimates of coastal and global averaged sea level for 1950 to 2000. During the 1990s and around 1970, we find coastal sea level is rising faster than the global average but that it rises slower than the global average during the late 1970s and late 1980s. The differences are largely a result of sampling the time‐varying geographical distribution of sea level rise along a coastline which is more convoluted in some regions than others. More rapid coastal rise corresponds to La Niña–like conditions in the tropical Pacific Ocean and a slower rate corresponds to El Niño–like conditions. Over the 51 year period, there is no significant difference in the rates of coastal and global averaged sea level rise, as found in climate model simulations of the 20th century. The best estimate of both global average and coastal sea level rise remains 1.8 ± 0.3 mm yr−1, as found in earlier studies.

IMPACTS ON THE COAST ZONE DUE TO STORM SURGE AND SEA LEVEL RISE OF GLOBAL WARMING IN THE SUO SEA

Global warming and its accompanying sea level rise will be serious issues in the future. According to the Intergovernmental Panel on Climate Change (IPCC), a global average sea level rise of 9cm to 88cm is projected for 1990 to 2100 and a steady increase of sea level for all of the scenarios considered is expected. In the coast regions, coast disasters caused by storm surge coupled with sea level rise are likely increased. To examine adaptation strategies against the increased coastal hazards, it is important to understand the characteristics of storm surge events. The aims of this study are to determine the most dangerous typhoon conditions in the Suo sea, to compute the maximum storm surge height, and to estimate the possible inundated area and population by using the Geographic Information Systems (GIS).

Estimates of the Regional Distribution of Sea Level Rise over the 1950–2000 Period

Abstract TOPEX/Poseidon satellite altimeter data are used to estimate global empirical orthogonal functions that are then combined with historical tide gauge data to estimate monthly distributions of large-scale sea level variability and change over the period 1950–2000. The reconstruction is an attempt to narrow the current broad range of sea level rise estimates, to identify any pattern of regional sea level rise, and to determine any variation in the rate of sea level rise over the 51-yr period. The computed rate of global-averaged sea level rise from the reconstructed monthly time series is 1.8 ± 0.3 mm yr−1. With the decadal variability in the computed global mean sea level, it is not possible to detect a significant increase in the rate of sea level rise over the period 1950–2000. A regional pattern of sea level rise is identified. The maximum sea level rise is in the eastern off-equatorial Pacific and there is a minimum along the equator, in the western Pacific, and in the eastern Indian Ocean. A g...

Climatology: threatened loss of the Greenland ice-sheet.

The Greenland ice-sheet would melt faster in a warmer climate and is likely to be eliminated--except for residual glaciers in the mountains--if the annual average temperature in Greenland increases by more than about 3 degrees C. This could raise the global average sea-level by 7 metres over a period of 1,000 years or more. We show here that concentrations of greenhouse gases will probably have reached levels before the year 2100 that are sufficient to raise the temperature past this warming threshold.

Simulated sea level in past and future climates of the Baltic Sea

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 27:59-75 (2004) - doi:10.3354/cr027059 Simulated sea level in past and future climates of the Baltic Sea H. E. Markus Meier*, Barry Broman, Erik Kjellström Swedish Meteorological and Hydrological Institute, Rossby Centre, 60176 Norrköping, Sweden *Email: markus.meier@smhi.se ABSTRACT: Sea levels of the Baltic Sea in past and future climates were investigated based upon 6-hourly regional model results. For the future climate, the Rossby Centre Atmosphere Ocean model was used to perform a set of 30 yr time slice experiments. For each of the 2 driving global models HadAM3H and ECHAM4/OPYC3, one control run (1961 to 1990) and 2 scenario runs (2071 to 2100) based upon the scenarios A2 and B2 of the special Report on Emission Scenarios (SRES) were conducted. To estimate uncertainties in the global and regional models, 3 sea level scenarios for the Baltic Sea were compiled assuming global average sea level rises between 0.09 and 0.88 m and considering land uplift and the impact of regional changes in wind direction and velocity from the time slice experiments. In the scenarios forced with ECHAM4/OPYC3 the mean sea level between October and April increases significantly compared to the control climate, and storm surges increase even more than monthly mean sea level. In the scenarios forced with HadAM3H the changes are mostly not significant. Depending on the sea level rise, the risk of flooding at the coasts may either decrease in the entire Baltic, or it may increase, especially at the eastern ends of the Gulf of Finland and Gulf of Riga and in Gdansk Bay. Here, maximum changes of about 1 m are found in the winter mean 99% quantiles of the sea level. For the past climate the regional ocean model was forced with reconstructed surface wind fields for 1903 to 1998. The results are close to observations, but storm surges in the western Baltic are underestimated. KEY WORDS: Baltic Sea · Sea level · Ocean modeling · Regional climate scenarios · Spatial planning Full article in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 27, No. 1. Online publication date: August 04, 2004 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2004 Inter-Research.

周防灘沿岸域における海面上昇による浸水ポテンシャルの推算

Global warming and its accompanying sea level rise will be serious issues in the future. According to the Intergovernmental Panel on Climate Change (IPCC), a global average sea level rise of 9cm to 88cm is projected for 1990 to 2100 and a steady increase of sea level for all of the scenarios considered is expected. In the coast regions, coast disasters caused by storm surge coupled with sea level rise are likely increased. To examine adaptation strategies against the increased coastal hazards, it is important to understand the characteristics of storm surge events. The aims of this study are to determine the most dangerous typhoon conditions in the Suo sea, to compute the maximum storm surge height, and to estimate the possible inundated areas by using GIS.

Simulated future sea-level rise due to glacier melt based on regionally and seasonally resolved temperature changes

Climate change is expected over the next century as a result of anthropogenic emissions of greenhouse gases and aerosols into the atmosphere, and global average sea level will consequently rise. Estimates1 indicate that by 2100 sea level will be about 500 mm higher than today as a result of global warming, with thermal expansion of sea water accounting for over half of this rise. The melting of glaciers and ice sheets will contribute much of the remainder. We present an improved calculation of glacier melt, which uses the temperature patterns generated by a coupled atmosphere–ocean general circulation model2,3 as inputs to a seasonally and regionally differentiated glacier model4,5. Under specified greenhouse-gas and sulphate-aerosol forcings, our model predicts that glacier melt equivalent to 132 mm of sea-level rise will occur over the period 1990–2100, with a further 76 mm from melting of the Greenland ice sheet. These figures fall within the range of previous estimates made using simpler models1; the advantage of our approach is that we take into account the effects of regional and seasonal temperature variations. Our inclusion of these effects increases the calculated glacier melt by 20%.

Sea Level Changes under Increasing Atmospheric CO2in a Transient Coupled Ocean-Atmosphere GCM Experiment

Abstract Climate change resulting from the enhanced greenhouse effect of increasing atmospheric CO2 concentrations is expected to bring about global and local changes in sea level. A global rise in sea level would result from thermal expansion of seawater and from melting of land ice, while changes in ocean dynamics and atmospheric pressure patterns could alter relative sea surface topography. Global and local sea level changes have been diagnosed from a 75-yr experiment with a version of the U.K. Meteorological Office coupled ocean-atmosphere general circulation model in which the CO2 concentration increases at 1% per year. Over the final decade, the component of mean global average sea level rise caused by thermal expansion is 90 mm; on this time scale, a significant contribution is expected from melting of mountain glaciers, but the model does not represent these. Sea level rises over practically the entire ocean area, but there is considerable variation in the magnitude, showing that the global figure...

Recent reports on the greenhouse effect

Two studies on the global warming trend are discussed. The EPA study predicts that CO/sub 2/ levels will reach 590 ppm (twice preindustrial levels) by 2060. Increases in CO/sub 2/ and other greenhouse gases would most likely cause a 2/sup 0/C warming by 2040 and a 5/sup 0/C increase by 2100. These changes are likely to be accompanied by dramatic changes in precipitation and storm patterns and a rise in global average sea level. The National Research Council (NRC) report predicts that if no corrective measures are taken, CO/sub 2/ levels will most likely double at about the same time as in the EPA study, with a temperature change of 1.5 C to 4.5 C. The analytical techniques of both studies are presented, as well as strategies on reducing CO/sub 2/ levels.