2,178 research outputs found
Sea-level rise in the Mediterranean Sea by 2050: Roles of terrestrial ice melt, steric effects and glacial isostatic adjustment
No full textTo assess the regional pattern of future low-frequency sea-level variations in the Mediterranean Sea, we combine the terrestrial ice melt, the glacio-isostatic and the steric sea-level components. The first is obtained from global scenarios for the future mass balance of the Greenland and Antarctica ice sheets, glaciers and ice caps. The second is based on modeling, using different assumptions about the Earth's rheology and the chronology of deglaciation since the Last Glacial Maximum. The third is obtained from published simulations based on regional atmosphere–ocean coupled models. From a minimum and a maximum scenario by 2040–2050, we find that the total, basin averaged sea-level rise will be 9.8 and 25.6 cm. The terrestrial ice melt component will exceed the steric contribution, which however will show the strongest regional imprint. Glacial isostatic adjustment will have comparatively minor effects. According to our estimates, at the Mediterranean Sea tide gauges, the rate of sea-level change will increase, by 2050, by a factor of ~ 1–6 relative to the observed long-term rates
New estimates of secular sealevel rise from tide gauge data and GIA modeling
No full textDuring the last three decades, at least thirty independent estimates of the secular
global mean sea–level rise (GMSLR) have been published, based on sufficiently long
tide gauge records. Despite its apparent simplicity, the problem of GMSLR is fraught
with a number of difficulties, which make it one of the most challenging questions
of climate change science. Not surprisingly, published estimates show considerable
scatter, with rates ranging between 1 and 2 mm/yr for observations on the century
time scale. In previous work, the importance of Glacial Isostatic Adjustment (GIA)
upon the assessment of the GMSLR has been clearly demonstrated. In particular,
starting from the 80s, GIA models have been routinely employed to decontaminate
tide gauge observations from the effects of melting of the late–Pleistocene ice sheets,
in order to fully highlight the sea–level variations driven by climate change. However,
uncertainties associated with the Earth’s rheological profile and the time history of
the past continental ice sheets can propagate into the GIA corrections. After revisit-
ing previous work and estimates, we suggest a significant modification of the criteria
for the selection of the tide gauges which are most suitable for the robust assessment
of the secular GMSLR. In particular, we seek a set of tide gauges for which GIA
corrections are essentially independent of the parameterization of the rheological
profile of the Earth’s mantle and of the detailed time–chronology of surface loading.
This insensitivity is established by considering predictions based upon three GIA
models widely employed in the recent literature (namely, ICE–3G, ICE–5G and the
one developed at the Research School of Earth Sciences of the National Australian
University). Applying this approach and selection criteria previously proposed in
the literature, we identify a set of 22 sufficiently evenly distributed tide gauges.
By simple statistical methods, these records yield a “preferred”, GIA–independent
GMSLR estimate since 1880, namely 1.5 ± 0.1 mm/yr (rms=0.4 mm/yr, wrms=0.3
mm/yr). This value is consistent with various previous estimates based on secular
tide gauge observations and with that proposed, for the 20th century, by the IPCC
Fourth Assessment Report (1.7 ± 0.5 mm/yr)
Linear and non-linear sea-level variations in the Adriatic Sea from tide gauge records (1872-2012)
No full textWe have analyzed tide gauge data from the Adriatic Sea in order to assess
the secular sea-level trend, its acceleration and the existence of
possible cyclic variation. Analyzing the sea-level stack of all Adriatic
tide gauges, we have obtained a trend of (1.25±0.04) mm yr-1, in agreement
with that observed for the last century in the Mediterranean Sea,
and an acceleration that is negligibile compared to the average global
values. By means of the Ensemble Empirical Mode Decomposition technique,
we have evidenced an energetic oscillation with a period of ∼20
years that we relate with the recurrence of opposite phases in the Atlantic
Multi–decadal Oscillation and North Atlantic Oscillation indices.
We suggest that anomalously high sea-level values observed at
all the Adriatic tide gauges during 2010 and 2011 can be explained by
the rising phase of this 20 years cycl
Extent and dynamic evolution of the lost land aquaterra since the Last Glacial Maximum
No full textWe study the evolution of a recently recognised global geographical feature, named aquaterra, enclosing those lands that in previous glacial cycles have been repeatedly exposed and flooded. So far, the geography of aquaterra has been studied as a first approximation neglecting the isostatic effects and assuming globally uniform (i.e. eustatic) sea-level variations. Focussing on the last deglaciation and considering both global and regional aspects, we show that isostatic effects related with mantle dynamics have indeed played a significant role in the evolution of aquaterra. Our analysis is based upon paleogeographic reconstructions in the framework of well-established Glacial Isostatic Adjustment theories
Spectral analysis of sea level during the altimetry era, and evidence for GIA and glacial melting fingerprints
No full textWe study the spatial patterns of the mass and steric components of sea-level change during the "altimetry era" (1992-today), and we characterize them at different scales by the orthonormal functions method. The spectrum of the altimetry-derived rate of sea-level rise is red and decays with increasing wavenumber nearly following a power law with exponent ≈. 2. By analyzing the degree correlation and the admittance function, we find that the altimetric rate of sea-level change is coherent with the total steric field in the whole range of wavelengths considered (down to ≈. 1000 km), but particularly for wavelengths exceeding ≈. 2000 km. Thermosteric and halosteric components are moderately anti-correlated within the range of wavelengths 1000-4000 km. Their power spectrum varies significantly with the wavelength and, for ≈. 2000 km, it is equally partitioned between the two components. The power of regional sea-level variations driven by Glacial Isostatic Adjustment and the melting of continental ice sheets is small compared to that held by the steric component, which explains most of the regional variability shown by the altimetry record. This causes the elusiveness of the "static" sea-level fingerprints, which at present are hidden in the pattern of the residual sea-level (i.e., the altimetry-derived sea-level minus the steric component). However, we find that at harmonic degree 2, mainly associated with rotational variations, the power of glacial melting is significant and it will progressively increase during next century in response to global warming. We also estimate that at the end of the Mid-Holocene the strength of the glacial isostatic readjustment fingerprints was ≈. 10 times larger than today, well above the long-wavelength component of residual sea-level. © 2016 Elsevier B.V
Desativar o direito: um caminho a partir da obra de Giorgio Agamben
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Jurídicas, Programa de Pós-Graduação em Direito, Florianópolis, 2014O trabalho parte do problema de tentar pensar uma forma de resistência pelo Direito. A hipótese sustentada encontra amparo na noção de "desativar" o Direito, contida na obra de Giorgio Agamben. Neste sentido, o trabalho busca recompor os paradigmas jurídico-político e governamental dentro da obra do autor em questão, principalmente a partir dos livros "O poder soberano e a vida nua", "Estado de Exceção" e "O Reino e a Glória". Ao fim, a proposta de "desativar" o Direito e o conceito de inoperosidade defrontam-se com a máquina governamental agambeniana. Na conclusão, a filosofia do Direito é apresentada como alternativa para se pensar uma nova relação entre Direito e vida.Abstract: The work begins from the problem of trying to think of a way of resistance by Law. The hypothesis is supported by the notion of "deactivate" the law, contained in the work of Giorgio Agamben. In this sense, this dissertation seeks to reconstruct the legal-political and governmental paradigms within the work of the author in question, mostly from the books "The sovereign power and bare life", "State of Exception" and "The Kingdom and the Glory". At the end, the proposal to "deactivate" the Law and the concept of unindustriousness are confronted with Agamben's government machinery. In conclusion, the philosophy of law is presented as an alternative to think about a new relationship between law and life
The Bering Transitory Archipelago: stepping stones for the first Americans
No full textRetrospective sea-level mapping advances a promising geographic solution to the longstanding mystery about when, where, and how the first Americans crossed over from Asia. A paleotopographic reconstruction accounting for Glacial Isostatic Adjustment digitally explores an archipelago about 1400 km long that likely existed from >30,000 BP to 8000 BP. Here the authors examine this Bering Transitory Archipelago in regard to established hypotheses—Clovis-first, Ice-free (deglaciation) Corridor, Kelp Highway, and Beringian Standstill hypotheses—and a new Stepping-Stones hypothesis. Scores of islands at that time would meet all requirements previously proposed for a viable hypothesis: a source population in Asia, a pathway with abundant sustenance, settlements in North America soon after but not before, and an isolated sanctuary where Beringians could have become genetically distinct
Gas odorization analysis device and method
No full textIn this patent an instrument and the method for the odorization and the quantitative detection of tetrahydrothiofene in methane pipeline has been planned and made
Global Choke Points May Link Sea Level And Human Settlement At The Last Glacial Maximum
No full textGlobal choke points are preeminent nodes in geographic networks and geopolitical touchpoints subject to control by nations. They appear today as recurring theaters of conflict worldwide and also in archaeological investigations delving thousands of years back in time. How different were today’s global choke points at the Last Glacial Maximum (LGM) ~ 20,000 years ago? For the first time, we map nine of them to visualize their conditions at LGM. The global feature aquaterra—all lands inundated and exposed repeatedly during the Late Pleistocene ice ages—initially was mapped as first approximations of sea level. Here we refine its boundaries using Glacial Isostatic Adjustment (GIA) models to account for the Earth’s deformation and horizontal migrations of shorelines in response to glacial melting. We found three choke points sufficiently open to navigation, but six others presented substantially greater barriers than today. Implications include strategic insights on where to search for submerged evidence of human settlement
Anomalous secular sea-level acceleration in the Baltic Sea caused by isostatic adjustment
No full textObservations from the global array of tide gauges show that global sea-level has been rising at an average rate of 1.5-2 mm/yr during the last ~150 years [Douglas 1991, Spada and Galassi 2012]. Although a global sea-level acceleration was initially ruled out [Douglas 1992], subsequent studies [Douglas 1997, Church and White 2006, Jevrejeva et al. 2008, Church and White 2011] have coherently proposed values of ~1 mm/year/century [Olivieri and Spada 2013]. More complex non-linear trends and abrupt sea-level variations have now also been recognized. Globally, these could manifest a regime shift between the late Holocene and the current rhythms of sea-level rise [Gehrels and Woodworth 2013], while locally they result from ocean circulation anomalies, steric effects and wind stress [Bromirski et al. 2011, Merrifield 2011]. Although isostatic readjustment affects the local rates of secular sea-level change [Milne and Mitrovica 1998, Peltier 2004], a possible impact on regional acceleration has been so far discounted [Douglas 1992, Jevrejeva et al. 2008, Woodworth et al. 2009] since the process evolves on a millennium time scale [Turcotte and Schubert 2002]. Here we report a previously unnoticed anomaly in the long-term sea-level acceleration of the Baltic Sea tide gauge records, and we explain it by the classical post-glacial rebound theory and numerical modeling of glacial isostasy. Contrary to previous assumptions, our findings demonstrate that isostatic compensation plays a role in the regional secular sea-level acceleration.</p
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