Literatura académica sobre el tema "Anthropic forcing"

We investigate the effects of correlated global regulation mechanisms, especially Galactic gamma-ray bursts (GRBs), on the temporal distribution of hypothetical inhabited planets, using simple Monte Carlo numerical experiments. Starting with recently obtained models of planetary ages in the Galactic Habitable Zone (GHZ), we obtain that the times required for biological evolution on habitable planets of the Milky Way are highly correlated. These results run contrary to the famous anti-SETI anthropic argument of Carter, and give tentative support to the ongoing and future SETI observation projects.

At many bank filtration (BF) sites, mixing ratios between the contributing sources of water are typically regarded as values with no temporal variation, even though hydraulic conditions and pumping regimes can be transient. This study illustrates how anthropic and meteorological forcings influence the origin of the water of a BF system that interacts with two lakes (named A and B). The development of a time-varying binary mixing model based on electrical conductivity (EC) allowed the estimation of mixing ratios over a year. A sensitivity analysis quantified the importance of considering the temporal variability of the end-members for reliable results. The model revealed that the contribution from Lake A may vary from 0% to 100%. At the wells that were operated continuously at >1000 m3/day, the contribution from Lake A stabilized between 54% and 78%. On the other hand, intermittent and occasional pumping regimes caused the mixing ratios to be controlled by indirect anthropic and/or meteorological forcing. The flow conditions have implications for the quality of the bank filtrate, as highlighted via the spatiotemporal variability of total Fe and Mn concentrations. We therefore propose guidelines for rapid decision-making regarding the origin and quality of the pumped drinking water.

This paper deals with monitoring systems to manage the risk due to fast slope failures that involve rock masses, in which important elements (such as infrastructures or cultural heritages, among the others) are exposed. Three different approaches for data analysis were here compared to evaluate their suitability for detecting mutual relations among destabilising factors, acting on different time windows, and induced strain effects on rock masses: (i) an observation-based approach (OBA), (ii) a statistics-based approach (SBA) and (iii) a semi-empirical approach (SEA). For these purposes, a test-site has been realised in an abandoned quarry in Central Italy by installing a multi-parametric monitoring sensor network on a rock wall able to record strain effects induced by natural and anthropic forcing actions (like as temperature, rainfall, wind and anthropic vibrations). The comparison points out that the considered approaches allow one to identify forcing actions, responsible for the strain effects on the rock mass over several time windows, regarding a specific size (i.e., rock block dimensional scale). The OBA was more suitable for computing the relations over short- to medium time windows, as well as the role of impulsive actions (i.e., hourly to seasonal and/or instantaneous). The SBA was suitable for computing the relations over medium- to long time windows (i.e., daily to seasonal), also returning the time lag between forcing actions and induced strains using the cross-correlation statistical function. Last, the SEA was highly suitable for detecting irreversible strain effects over long- to very long-time windows (i.e., plurennial).

AbstractSoil clay minerals in recent natural polders react on a human timescale in response to local environmental conditions. With increasing age, the mineral reaction leads to the dissolution of the chlorite component and a composition change of the different illite-smectite mixed-layer minerals (I-S MLMs): i.e. smectite layer content decreases and illite content increases. The process of oxidation, which is proven by magnetic susceptibility to trigger clay mineral reaction, changes the mineralogical composition of the sediment above the redox front. The mineral changes appear to be a non-linear function of time. In natural conditions the process lasts >1000 y. However, anthropoic forcing such as artificial drainage accelerates the oxidation reaction to complete the whole process in a few tens of years.

The nearly equal lunar and solar angular sizes as subtended at the Earth is generally regarded as a coincidence. This is, however, an incidental consequence of the tidal forces from these bodies being comparable. Comparable magnitudes implies strong temporal modulation, as the forcing frequencies are nearly but not precisely equal. We suggest that on the basis of palaeogeographic reconstructions, in the Devonian period, when the first tetrapods appeared on land, a large tidal range would accompany these modulated tides. This would have been conducive to the formation of a network of isolated tidal pools, lending support to A. S. Romer's classic idea that the evaporation of shallow pools was an evolutionary impetus for the development of chiridian limbs in aquatic tetrapodomorphs. Romer saw this as the reason for the existence of limbs, but strong selection pressure for terrestrial navigation would have been present even if the limbs were aquatic in origin. Since even a modest difference in the Moon's angular size relative to the Sun's would lead to a qualitatively different tidal modulation, the fact that we live on a planet with a Sun and Moon of close apparent size is not entirely coincidental: it may have an anthropic basis.

Currently the extension of human activities allows us to characterize the human being as a geological and biological forcing, capable of generating significant alterations both in the geochemical composition of the main reservoirs of the Earth surface and in biodiversity. Substantial variations of the atmosphere composition as well as of sedimentary constituents deposited in lacustrine environments and in coastal zones allow to easily identifying the anthropic influence on Terrestrial ecosystems. However, the nature of a forcing does not characterize the beginning of a new geological interval, but the extension of its expression on the Earth system. These issues raise a vigorous debate that seeks to understand not only how the human affects the planet, but also how much we can change surface geochemistry and biological activity. In this context, the search for a marker of Anthropogenic effects in geological materials is an important criterion for determining the Anthropocene as a new geological event on the planet. This paper proposes a brief discussion of the scale about environmental changes due to the anthropic action on the planet surface and its signature in the biogeochemical reservoirs with a view to presenting a suggestion for the beginning of the Anthropocene. Finally, we ponder the fact that we are not the first biological forcing to change the surface of the planet, but without doubt, we are the first forcing that has a moral dimension. ResumoA magnitude e extensão das atividades humanas permite-nos considerar o Homem como uma forçante geológica e biológica, capaz de originar alterações significativas tanto na composição geoquímica dos principais reservatórios da superfície Terrestre quanto na biodiversidade. Variações substanciais da composição da atmosfera, bem como de constituintes sedimentares depositados em ambientes lacustres e em zonas costeiras, permitem identificar facilmente a influência antrópica nos ecossistemas terrestres. No entanto, a natureza de um forçamento não caracteriza o início de um novo intervalo geológico, mas a extensão da sua expressão no sistema terrestre. Essas questões levantam um debate vigoroso que busca entender não apenas como o homem afeta o planeta, mas também o quanto podemos mudar a geoquímica da superfície Terrestre e a atividade biológica. Neste contexto, a busca por um marcador de efeitos antropogênicos em materiais geológicos é um importante critério para a determinação do Antropoceno como um novo evento geológico no planeta. Este trabalho, propõe uma breve discussão da escala sobre mudanças ambientais devido à ação antrópica sobre a superfície do planeta e sua assinatura nos reservatórios biogeoquímicos com o objetivo de apresentar uma sugestão para o início do Antropoceno. O Homem não é o primeiro forçador biológico a mudar a superfície do planeta, mas é, sem dúvida, a primeira força com dimensão moral.

Landscape evolution over the last 8000 years in three areas located along Tuscany, Latium, and Campania coasts (central Tyrrhenian) has been deduced through a morphological, stratigraphical, and historical approach considering the physical evolution and human activity. Between 8000 and 6000 yr BP, the Sea Level Rise (SLR) dominated and, near the river mouths, inlets occurred. In the Tuscany area, Mt. Argentario was an island and to SE of the Ansedonia promontory a lagoon occurred. The areas were covered by a dense forest and the human influence was negligible. Between 6000 and 4000 yr BP, humans organized settlements and activities, and a general coastline progradation occurred. A tombolo linked Mt. Argentario to the mainland. In the Tiber and Campania areas, coastal lakes and a strand plain developed. Between 4000 and 3000 yr BP, near Mt. Argentario, two tombolos enclosed a wide lagoon. At the SE of the Ansedonia promontory, the lagoon split into smaller water bodies. In the Tiber and Campania areas, delta cusps developed. The anthropogenic presence was widespread and forests decreased. During the last 3000 years, anthropic forcing increased when the Etruscans and Romans changed the territory through towns, salt pans, and ports. After the Roman period, natural forcing returned to dominate until the birth of the Italian State and technological evolution.

A numerical model, validated with field measurements, was applied to comparatively reconstruct the hydrodynamics of a eutrophic coastal lagoon in a set of scenarios over the last two centuries. The effect of major morphological changes on the water exchange with the open sea and water residence time is evaluated. The results show that the number and morphology of the lagoon inlets are crucial in determining the volume of water exchanged with the sea, the water transport timescales, and the extent of poorly circulated stagnant areas with poor flushing potential, which are areas where anoxic crises might develop. When all the relevant forcing mechanisms on the hydrodynamics are considered, great variability of the water residence time is found in the different historical scenarios, with values varying between 83 and 305 days. The effect of anthropic actions on the system hydrodynamics was quantitatively evaluated, consolidating the background knowledge to support the present and future management of this environmental system.

Abstract. Resilience is a fundamental concept for understanding vegetation as a dynamic component of the climate system. It expresses the ability of ecosystems to tolerate disturbances and to recover their initial state. Recovery times are basic parameters of the vegetation's response to forcing and, therefore, are essential for describing realistic vegetation within dynamical models. Healthy vegetation tends to rapidly recover from shock and to persist in growth and expansion. On the contrary, climatic and anthropic stress can reduce resilience thus favouring persistent decrease in vegetation activity. In order to characterize resilience, we analyzed the time series 1982–2003 of 8 km GIMMS AVHRR-NDVI maps of the Italian territory. Persistence probability of negative and positive trends was estimated according to the vegetation cover class, altitude, and climate. Generally, mean recovery times from negative trends were shorter than those estimated for positive trends, as expected for vegetation of healthy status. Some signatures of inefficient resilience were found in high-level mountainous areas and in the Mediterranean sub-tropical ones. This analysis was refined by aggregating pixels according to phenology. This multitemporal clustering synthesized information on vegetation cover, climate, and orography rather well. The consequent persistence estimations confirmed and detailed hints obtained from the previous analyses. Under the same climatic regime, different vegetation resilience levels were found. In particular, within the Mediterranean sub-tropical climate, clustering was able to identify features with different persistence levels in areas that are liable to different levels of anthropic pressure. Moreover, it was capable of enhancing reduced vegetation resilience also in the southern areas under Warm Temperate sub-continental climate. The general consistency of the obtained results showed that, with the help of suited analysis methodologies, 8 km AVHRR-NDVI data could be useful for capturing details on vegetation cover activity at local scale even in complex territories such as that of the Italian peninsula.

Le LiDAR aéroporté est principalement utilisé en archéogéographie sous couverture forestière et en géographie pour restituer les pratiques des sociétés sur le territoire et pour l’approche hydrogéomorphologique dans les corridors fluviaux. Mais les hydrosystèmes et le forçage anthropique des interfluves du Grand Est restent peu étudiés malgré une couverture LiDAR satisfaisante. La Montagne de Reims, correspondant à la terminaison orientale de la cuesta Île-de-France est utilisée comme atelier expérimental pour caractériser, par l’approche LiDAR, d’une part la structure de l’hydrosystème et d’autre part son évolution durant l’Holocène. C’est un espace singulier (surface de 250 km²) paradoxalement à fort potentiel de valorisation patrimoniale mais conditionné majoritairement à la forêt privée, limitant son accès et sa connaissance. La démarche consiste à croiser les données LiDAR à une analyse spatiale multicritères et multiscalaire sous SIG, à plusieurs échelles de temps (vision diachronique), avec l’approche expérimentale de terrain. Le traitement d’une géodatabase permet non seulement de discriminer les morphologies de l’hydrosystème selon des critères génétiques, historiques et hydrodynamiques mais aussi de comprendre leur organisation spatiale. Il montre que l’hydrosystème résulte d’une longue histoire polyphasée. Les paramètres structurant son organisation spatiale s’inscrivent dans un emboitement d’échelle. L’échelle géologique (conditions de dépôt du Paléogène) conditionne les disparités aquifères d’est en ouest. Le Quaternaire explique l’opposition entre les versants nord et sud en commandant le degré d’incision des vallées et les processus géomorphologiques (mouvements de terrain, karstification). À l’échelle historique, les forçages humain et climatique conditionnent les disparités hydrologiques entre les plateaux et les vallées. Enfin, un modèle conceptuel de l’hydrosystème actuel de la Montagne de Reims est proposé
Airborne LiDAR is mainly used in archaeogeography under forest cover and in geography to reconstruct the practices of societies on the land and for the hydrogeomorphological approach in river corridors. However, the hydrosystems and anthropogenic forcing of the interfluves of the Grand Est region remain understudied, despite a satisfactory LiDAR coverage. The Montagne de Reims, corresponding to the eastern end of the Île-de-France cuesta, is used as an experimental site to characterize, using the LiDAR approach, both the structure of the hydrosystem and its evolution during the Holocene. This is a singular area (surface of 250 km²) which paradoxically has a high potential for heritage valorization, but is mainly conditioned by private forests, limiting its access and understanding. The approach consists of cross-referencing LiDAR data with a multi-criteria and multi-scalar spatial analysis using GIS, on several time scales (diachronic vision), with the experimental field approach. Processing a geodatabase not only allows us to discriminate between hydrosystem morphologies according to their genetic, historical and hydrodynamic criteria, but also to understand their spatial organization. It shows that the hydrosystem is the result of a long, multi-phase history. The parameters structuring its spatial organization are part of an overlap of scales. The geological scale (Paleogene deposit conditions) conditions aquifer disparities from east to west. The Quaternary explains the opposition between north and south slopes by controlling the degree of valley incision and geomorphological processes (landslides, karstification). On a historical scale, human and climatic forcings condition hydrological disparities between plateaus and valleys. Finally, a conceptual model of the current hydrosystem of the Montagne de Reims is proposed