Human impacts overwhelm the effects of sea-level rise on Basque coastal habitats (N Spain) between 1954 and 2004

According to coastal measurements, global mean sea-level has risen at a rate of 1.8 mm yr⁻¹ between 1950 and 2000, with large spatial variability at regional scales. Within the Bay of Biscay, trends computed from coastal tide gauges records have revealed that sea-level rise is accelerating over this period of time; this is in agreement with rates obtained from satellite imagery in the open ocean since 1993. The objectives of the present study are: (1) to assess the evidence of the relative sea-level rise on coastal morphology and habitats in the Gipuzkoan littoral zone (Basque coast, northern Spain) for the period 1954–2004, and (2) to evaluate the relative contribution of local anthropogenic versus sea-level rise impacts for explaining inter-supratidal habitat changes. A high-resolution airborne laser altimetry data (LIDAR) has been used to derive a Digital Terrain Model (DTM) of 15-cm vertical resolution. Coastal habitats were mapped for two periods, using historic airborne photography (1954) and high-resolution imagery (2004). Analysis of tide gauge records from Santander (northern Spain) has revealed that relative mean sea-level has been rising at a rate of 2.08 ± 0.33 mm yr⁻¹ from 1943 to 2004; this is consistent with sea-level trends from other measurements within the area (St. Jean de Luz and Bilbao), obtained over shorter periods of time, and with previous results obtained in the Bay of Biscay. Based upon this sea-level trend and by means of a LIDAR-based DTM, the results have indicated that the predicted change along the Gipuzkoan coast due to sea-level rise was of 11.1 ha within the 50-yr period. In contrast, comparison of historical and recent orthophotography has detected only 2.95 ha of change, originated possibly from sea-level rise, and 98 ha transformed by anthropogenic impacts. Hence, coastal changes due to sea-level rise might be overwhelmed by excessive human impacts, at the spatial and temporal scales of the analysis. This work highlights that local anthropogenic impact is the major threat to Basque coastal and estuarine habitats, compared with natural erosive processes and global climate change driving forces over recent times.     

Climate of the last millennium: a sensitivity study

Seventy-one sensitivity experiments have been performed using a two-dimensional sector-averaged global climate model to assess the potential impact of six different factors on the last millennium climate and in particular on the surface air temperature evolution. Both natural (i.e, solar and volcanism) and anthropogenically-induced (i.e. deforestation, additional greenhouse gases, and tropospheric aerosol burden) climate forcings have been considered.
Comparisons of climate reconstructions with model results indicate that all the investigated forcings are needed to simulate the surface air temperature evolution. Due to uncertainties in historical climate forcings and temperature reconstructions, the relative importance of a particular forcing in the explanation of the recorded temperature variance is largely function of the forcing time series used. Nevertheless, our results indicate that whatever the historical solar and volcanic reconstructions may be, these externally driven natural climate forcings are unable to give climate responses comparable in magnitude and time to the late–20th-century temperature warming while for earlier periods combination of solar and volcanic forcings can explain the Little Ice Age and the Medieval Warm Period. Only the greenhouse gas forcing allows the model to simulate an accelerated warming rate during the last three decades. The best guess simulation (largest similarity with the reconstruction) for the period starting 1850 AD requires however to include anthropogenic sulphate forcing as well as the impact of deforestation to constrain the magnitude of the greenhouse gas twentieth century warming to better fit the observation. On the contrary, prior to 1850 AD mid-latitude land clearance tends to reinforce the Little Ice age in our simulations.     

Future sea-level rise and its early detection by satellite remote sensing

During the past 100 years, sea-level appears to have risen by 10–15cm, probably due to the combined effects of thermal expansion of ocean-surface waters and net melting of glaciers and ice caps, associated with a small increase in global temperatures. This trend will almost certainly continue and accelerate if steadily increasing levels of carbon dioxide and other “greenhouse” gases in the atmosphere cause warming of the magnitude widely predicted by climate modellers. Rising air temperatures will cause increased melting from glaciers and ice caps, and rising sea-water temperatures will cause thermal expansion of the oceans. Moreover, warmer ocean waters could melt and weaken the many floating ice shelves that surround Antarctica, permitting increased ice discharge from glaciers that flow into them. All of these factors would cause sea-level to rise, and this paper presents and estimate of the total sea-level rise that could occur during the next century.If, as predicted by many climate models, global temperatures increase by an average of about 3°C, there is a good probability that sea-level will rise approximately 1m by the year 2100. Ultimately, such a rise would become very apparent to coastal populations, but initial change would be slow. Consequently, it is important to devise and “early warning system” for prompt detection of changes that will precede a detectable rise in sea level. These include: surface temperatures on land, oceans and ice sheets; sea-ice distribution; extent of summer melting on the polar ice sheets; areal extent and surface elevations of the ice sheets in Greenland and Antarctica. All of these parameters can be measured from space by satellites that are operating now or are planned for launch during the next few years     

沿海水位和大尺度气候状态——降尺度技术在日本列岛的应用

沿海水位和大尺度气候状态——降尺度技术在日本列岛的应用     

Spectral properties of sea level and time scales of Kuroshio path variations

Spectral properties of sea levels at Naze, Nishinoomote, Kushimoto, Uragami, Miyake-jima and HachijÔ-jima are examined for the non-large-meander (February 1964 – May 1975) and large-meander (October 1975 – December 1979) periods, and the periodicity of variation of the Kuroshio path is clarified.The large meander of the Kuroshio occurs with a primary period of about 20 years and secondary period of 7 to 8. 5 years. During the non-large-meander period, the Kuroshio alternately takes the nearshore and offshore non-large-meander paths with a primary period of 1. 6–1. 8 years. This variation is moreover composed of 110-day, around 195-day and annual periods. The 110-day variation of the Kuroshio path appears to have influence on the coastal sea levels between the Kii Peninsula and the Izu Ridge;i. e., the coastal sea levels rise and fall with one-month time lag after the Kuroshio has begun to approach and leave the Japanese coast. During the large-meander period, the 70 and 110-day variations are remarkable in sea levels south of Japan except Miyake-jima and HachijÔ-jima. The 70-day variation is highly coherent throughout the south coast of Japan; the coherent area of the 110-day variation seems to be smaller.The sea-level variations at Naze and Nishinoomote are not significantly coherent for any of the periods except for annual and semiannual cycles during both the non-large-meander and large-meander periods. That is, the sea-level variations are incoherent between the onshore and offshore sides of the Kuroshio, except for seasonal variation.     

One-Dimensional Hydraulic Analysis of the Effect of Sea Level Rise on Salinity Intrusion in the Sebou Estuary,Morocco

Global climate change has resulted in a gradual sea-level rise. Sea-level rise can cause saline water to migrate upstream in estuaries and rivers, thereby threatening freshwater habitat and drinking water supplies. On the other hand, sea-level rise, resulting from thermal expansion of ocean waters and increased melting of glaciers and ice caps, is one of the most apparent and widespread consequences of climate change. This phenomenon has been taken into account in all the Assessment Reports published by the Intergovernmental Panel on Climate Change (IPCC). In this paper, salinity intrusion and intrusion length due to possible sea-level rise in the Sebou estuary (Morocco) was investigated. A one-dimensional hydrodynamic-salinity transport model was used for the simulation of the salinity intrusion and associated water quality, with observed field data being used for model calibration and validation. Additionally, the model validation process showed that the model results fit the observed data fairly well. A coupled gas-cycle/climate model was used to generate the climate change scenarios in the studied area that showed sea-level rises varying from 0.3 to 0.9 m for 2100. The models were then combined to assess the impact of future sea-level rise on the salinity distribution and intrusion length in the Sebou estuary. The response of salt intrusion length to changes in important dimensional parameters are presented, showing that the salinity intrusion length is inversely correlated with the river discharge, i.e., a high river discharge results in a reduced salt intrusion and vice versa, and directly with the sea-level rise. Additionally, the magnitude and frequency of the salinity standard violations at the two pump stations were predicted for 2100, showing that the salinity violations under climate change effects can increase to ～45–48% of the times at these locations. Finally, the main objective of this simulation method is to accelerate and facilitate of systems' behavior learning in the current and future situation.     

Structure of temperature variability in the high latitudes of the Northern Hemisphere

The spatial structure of surface air temperature (SAT) anomalies in the extratropical latitudes of the Northern Hemisphere (NH) during the 20th century is studied from the data obtained over the period 1892–1999. The expansion of the mean (over the winter and summer periods) SAT anomalies into empirical orthogonal functions (EOFs) is used for analysis. It is shown that variations in the mean air temperature in the Arctic region (within the latitudes 60°–90°N) during both the winter and summer periods can be described with a high accuracy by two spatial orthogonal modes of variability. For the winter period, these are the EOF related to the leading mode of variability of large-scale atmospheric circulation in the NH, the North Atlantic Oscillation, and the spatially localized (in the Arctic) EOF, which describes the Arctic warming of the mid-20th century. The expansion coefficient of this EOF does not correlate with the indices of atmospheric circulation and is hypothetically related to variations in the area of the Arctic ice cover that are due to long-period variations in the influx of oceanic heat from the Atlantic. On the whole, a significantly weaker relation to the atmospheric circulation is characteristic of the summer period. The first leading variability mode describes a positive temperature trend of the past decades, which is hypothetically related to global warming, while the second leading EOF describes a long-period oscillation. On the whole, the results of analysis suggest a significant effect of natural climatic variability on air-temperature anomalies in the NH high latitudes and possible difficulties in isolating an anthropogenic component of climate changes.     

Climate and carbon cycle variations in the 20th and 21st centuries in a model of intermediate complexity

The climate model of intermediate complexity developed at the Oboukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM), has been supplemented by a zero-dimensional carbon cycle model. With the carbon dioxide emissions prescribed for the second half of the 19th century and for the 20th century, the model satisfactorily reproduces characteristics of the carbon cycle over this period. However, with continued anthropogenic CO₂ emissions (SRES scenarios A1B, A2, B1, and B2), the climate-carbon cycle feedback in the model leads to an additional atmospheric CO₂ increase (in comparison with the case where the influence of climate changes on the carbon exchange between the atmosphere and the underlying surface is disregarded). This additional increase is varied in the range 67–90 ppmv depending on the scenario and is mainly due to the dynamics of soil carbon storage. The climate-carbon cycle feedback parameter varies nonmonotonically with time. Positions of its extremes separate characteristic periods of the change in the intensity of anthropogenic emissions and of climate variations. By the end of the 21st century, depending on the emission scenario, the carbon dioxide concentration is expected to increase to 615–875 ppmv and the global temperature will rise by 2.4–3.4 K relative to the preindustrial value. In the 20th–21st centuries, a general growth of the buildup of carbon dioxide in the atmosphere and ocean and its reduction in terrestrial ecosystems can be expected. In general, by the end of the 21st century, the more aggressive emission scenarios are characterized by a smaller climate-carbon cycle feedback parameter, a lower sensitivity of climate to a single increase in the atmospheric concentration of carbon dioxide, a larger fraction of anthropogenic emissions stored in the atmosphere and the ocean, and a smaller fraction of emissions in terrestrial ecosystems.     

Simulation and prediction of climate changes in the 19th to 21st centuries with the Institute of Numerical Mathematics, Russian Academy of Sciences, model of the Earth’s climate system

This paper presents results from a simulation of climate changes in the 19th–21st centuries with the Institute of Numerical Mathematics Climate Model Version 4 (INMCM4) in the framework of the Coupled Model Intercomparison Project, phase 5 (CMIP5). Like the previous INMCM3 version, this model has a low sensitivity of 4.0 K to a quadrupling of CO₂ concentration. Global warming in the model by the end of the 21st century is 1.9 K for the RCP4.5 scenario and 3.4 K for RCP8.5. The spatial distribution of temperature and precipitation changes driven by the enhanced greenhouse effect is similar to that derived from the INMCM3 model data. In the INMCM4 model, however, the heat flux to the ocean and sea-level rise caused by thermal expansion are roughly 1.5 times as large as those in the INMCM3 model under the same scenario. A decrease in sea-ice extent and a change in heat fluxes and meridional circulation in the ocean under global warming, as well as some aspects of natural climate variability in the model, are considered.     

中国近海海平面变化半经验预测方法研究

由于用数值模式预测未来海平面变化存在很大的不确定性,而统计预测方法又通常不考虑相关物理过程,为此Rahmstorf通过建立海平面变化与全球气温变化的相关模型,提出了一个可行的半经验方法预测全球海平面.本文将Rahmstoff模型应用于中国近海,初步建立了一个在气候变暖背景下中国近海海平面长期变化的预测方法,预测结果表明...     

1988年以来气候控制的南流江河口红树林扩张

基于卫星图像重建了近30年来广西南流江河口区一片红树林的扩张过程,结果表明：自1988年至2013年,该红树林向海显著扩张,面积由60公顷增加为134公顷。红树林的自然扩张并非渐进式,而是集中发生于某些特定时期。为了研究控制红树林扩张的动力机制,本文研究了近几十年来红树林潮坪高程演变和区域气候变化过程,同时也分析了水动力状况和营养盐供应的变化情况。研究表明：在滩面高程达到红树林幼苗存活最低高程的前提下,台风强度、频率和冬季低温是控制该红树林扩张的关键因素。红树林湿地的显著扩张只发生在台风强度和频率较低、冬季较为温暖的时期。而在台风频率和强度较高、冬季较为寒冷的时期,由于红树林幼苗难以存活,红树林则难以扩张。在过去几十年间,由于该区域适宜红树林扩张的时期较为罕见,从而导致了红树林扩张过程的不连续性。与气候因素相比,营养供应和水动力状况并不是控制该红树林扩张的关键因素。     

95年来青岛气候变化的分析

根据１８９８—１９９２年青岛年平均温度和降水资料，分析了青岛９５年来的气候变化，指出年平均气温有明显变暖趋势，而降水量变化不显著。分析了年平均温度和降水的气候阶段，还采用信噪比方法检验了９５年来青岛气候突变。利用谱分析方法分析了气温和降水的主要周期。这些结果与北半球和我国近百年的气候变化趋势基本一致。     

Threats to sandy beach ecosystems: A review

We provide a brief synopsis of the unique physical and ecological attributes of sandy beach ecosystems and review the main anthropogenic pressures acting on the world's single largest type of open shoreline. Threats to beaches arise from a range of stressors which span a spectrum of impact scales from localised effects (e.g. trampling) to a truly global reach (e.g. sea-level rise). These pressures act at multiple temporal and spatial scales, translating into ecological impacts that are manifested across several dimensions in time and space so that today almost every beach on every coastline is threatened by human activities. Press disturbances (whatever the impact source involved) are becoming increasingly common, operating on time scales of years to decades. However, long-term data sets that describe either the natural dynamics of beach systems or the human impacts on beaches are scarce and fragmentary. A top priority is to implement long-term field experiments and monitoring programmes that quantify the dynamics of key ecological attributes on sandy beaches. Because of the inertia associated with global climate change and human population growth, no realistic management scenario will alleviate these threats in the short term. The immediate priority is to avoid further development of coastal areas likely to be directly impacted by retreating shorelines. There is also scope for improvement in experimental design to better distinguish natural variability from anthropogenic impacts. Sea-level rise and other effects of global warming are expected to intensify other anthropogenic pressures, and could cause unprecedented ecological impacts. The definition of the relevant scales of analysis, which will vary according to the magnitude of the impact and the organisational level under analysis, and the recognition of a physical–biological coupling at different scales, should be included in approaches to quantify impacts. Zoning strategies and marine reserves, which have not been widely implemented in sandy beaches, could be a key tool for biodiversity conservation and should also facilitate spillover effects into adjacent beach habitats. Setback and zoning strategies need to be enforced through legislation, and all relevant stakeholders should be included in the design, implementation and institutionalisation of these initiatives. New perspectives for rational management of sandy beaches require paradigm shifts, by including not only basic ecosystem principles, but also incentives for effective governance and sharing of management roles between government and local stakeholders.     

气候变暖与海平面上升

本文通过大量实际资料分析认为,现代全球变暖与海平面上升,源于200多年前小冰期冷峰出现后的气候返暖、海平面回升过程演变的结果。近30年的世界海平面上升的速率,有着上世纪80、90年代和本世纪前10年世界平均气温每10年以0．2F°（0．11℃）为梯度的连续抬升为背景。在此以CO。含量为气候指标,划分出了公元200年以来的八个暖段（暖期）。若按冷暖极值距200年或250年计算,则由目前正在发展的暖期,将在公元2050年或2100年前后结束,而后开始降温。作者依据最近30年同一时段国内外验潮资料计算获得的绝对海平面升降速率为＋1．52±0．27mm／a及相对海平面升降速率为＋1．39±0．26mm/a。按照2010年坎昆气候大会决议要求,在对前人有关研究成果进行考量时,对将来的2050和2100年世界海平面预测及我国地面沉降较明显的沿海城市如天津、上海、厦门、海口等相对海平面升降值,进行了测算与评估。     

Influence of volcanic activity on climate change in the past several centuries: Assessments with a climate model of intermediate complexity

The climate model of intermediate complexity developed at the A.M. Obukhov Institute of Atmospheric Physics of the Russian Academy of Sciences (IAP RAS CM) is supplemented by a scheme which takes into account the volcanic forcing of climate. With this model, ensemble experiments have been conducted for the 1600s–1900s, in which, along with the volcanic forcing, the anthropogenic forcing due to greenhouse gases and sulfate aerosols and the natural forcing due to variations in solar irradiance were taken into account. The model realistically reproduces the annual mean response of surface air temperature and precipitation to major eruptions both globally and regionally. In particular, the decreases in the annual mean global temperature T _g in the IAP RAS CM after the largest eruptions in the latter half of the 20th century, the Mt. Agung (1963), El Chichon (1982), and Mt. Pinatubo (1991) volcanic eruptions, are 0.28, 0.27, and 0.46 K, respectively, in agreement with estimates from observational data. Moreover, in the IAP RAS CM, the volcanic eruptions result in a general precipitation decrease, especially over land in the middle and high latitudes of the Northern Hemisphere. The seasonal distribution of the response shows good agreement with observations for high-latitude eruptions and worse agreement for tropical and subtropical volcanoes. On interdecadal scales, volcanism leads to variations in T _g on the order of 0.1 K. In numerical experiments with anthropogenic and natural forcings, the model reproduces a general change in surface air temperature over the past several centuries. Taking into account the volcanic forcing, along with that due to variations in solar irradiance, the model has partly reproduced the nonmonotonic global warming for the 20th century.     

Assessing the global averaged sea-level budget from 2003 to 2010

A global mass balance （Greenland and Antarctica ice sheet mass loss, terrestrial water storage） and differ- ent sea-level components （observed sea-level from satellite altimetry, steric sea-level from Ishii data, and ocean mass from gravity recovery and climate experiment, GRACE） are estimated, in terms of seasonal and interannual variabilities from 2003 to 2010. The results show that a detailed analysis of the GRACE time series over the time period 2003-2010 unambiguously reveals an increase in mass loss from the Greenland ice sheet and Antarctica ice sheet. The mass loss of both ice sheets accelerated at a rate of （392.8±70.0） Gt/a during 2003-2010, which contributed （1.09±0.19） mm/a to the global mean sea-level during this time. The net terrestrial water storage （TWS） trend was negative over the 8 a time span, which gave a small positive contribution of （0.25±0.12） mm/a. The interannual variability of the global mean sea-level was at least part- ly caused by year-to-year variability of land water storage. Estimating GRACE-based ice sheet mass balance and terrestrial water storage by using published estimates for melting glaciers, the results further show that the ocean mass increase since 2003 has resulted half from an enhanced contribution of the polar ice sheets, and half from the combined ice sheet and terrestrial water storage loss. Taking also into account the melt- ing of mountain glaciers （0.41 mm/a） and the small GRACE-based contribution from continental waters （0.25 mm/a）, a total ocean mass contribution of （1.75±0.57） mm/a from 2003 to 2010 is found. Such a value represented 75% of the altimetry-based rate of sea-level rise over that period. The contributions to steric sea-level （i.e., ocean thermal expansion plus salinity effects） are estimated from： （1） the difference between altimetry-based sea-level and ocean mass change and （2） the latest Ishii data. The inferred steric sea-level rate from （1） （1.41 mm/a from 2003 to 2010） did not agree well with the Ishii-based value also estimated here （0.44 mm/a from 2003 to 2010）, but phase. The cause for such a discrepancy is not yet known but may be related to inadequate sampling of in situ ocean temperature and salinity measurements.     

Annual variation rate of global sea-level rise and the prediction for the 21st century

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Global cyclostratigraphy: a model of carbonate growth patterns

Cyclostratigraphy is the study of cyclic depositional patterns produced by climatic and tectonic processes. A global-scale quantitative cyclostratigraphic model is described which simulates carbonate growth patterns controlled by tectonic and climatic processes. The model uses seven factors simulating the effects of physical and chemical environments on the deposition rates of carbonate accumulations. These factors are sea-level change, the rate of basement subsidence, food supply (influence of nutrients), available sunlight, temperature, salinity and dissolved oxygen. The factors are considered as functions of climatic and tectonic processes. The model also integrates Milankovitch-induced short-term climatic changes with the long-term tectonic evolution of basins to examine the potential carbonate accumulation patterns. The two-dimensional computer model results provided here show that: (1) carbonate growth patterns in different climates and under different tectonic processes can be modelled quantitatively; (2) carbonate production increases towards the equator (decreasing latitude) as the temperature and nutrition supply increase in tropical belts, and production changes because of expansion or contraction of the tropical belt in different climatic periods; (3) when matched with the turbidity, the model describes different carbonate accumulation patterns in different climatic patterns; (4) at either abnormally high or low salinity, carbonate accumulation rates decline sharply, and the salinity becomes normal away from the strand line; and (5) cyclic sea-level changes cause a cyclic change of carbonate accumulation. A case study is presented from the Upper Pennsylvanian of Texas. The simulation results indicate that carbonate growth patterns observed from field, well or seismic data are accurately modelled by the quantitative procedure given here.     

Study of the mutual influence of the El Niño-Southern Oscillation processes and the North Atlantic and Arctic Oscillations

On the basis of the nonlinear techniques for the estimation of coupling between oscillatory systems from time series, we investigate the dynamics of climatic modes characterizing global and Northern Hemisphere (NH) processes. The North Atlantic Oscillation (NAO) and Arctic Oscillation indices and the El Niño-Southern Oscillation (ENSO) indices are analyzed in terms of the most reliable data from 1950 through 2004 and earlier data since the 19th century. These indices characterize changes in NH atmospheric pressure (specifically, sea-level pressure in the North Atlantic and NH extratropical latitudes as a whole) and in equatorial Pacific sea-surface temperature and sea-level pressure to which the strongest variations of global surface temperature and global climate on interannual time scales and of regional climatic anomalies in the NH are linked. The methods used are based on phase-dynamics modeling and nonlinear prediction models (a nonlinear version of Granger causality). From both methods and various ENSO indices, the inference about the ENSO effect on the NAO during the latter half of the 20th century and in the early 21st century is made with confidence probability of at least 0.95. The influence is characterized by a time delay of about two years. No inverse influence is found with a similar degree of reliability. Results of estimating the coupling between the ENSO and the NAO depend on the type of index that is used to describe the NAO. The ENSO effect on the NAO is detected with sufficient confidence when the NAO index is chosen to be a larger scale characteristic. However, when a more local index of the NAO is used, no statistically significant coupling to the ENSO is found. Increasing the length of the analyzed ENSO and NAO series (over more than 100 yr) does not lead to any more reliable detection of coupling. Analysis of the data for different time intervals during 1950–2004 has revealed a strengthening of the ENSO effect on the NAO, although this inference is not reliable.