Letteratura scientifica selezionata sul tema "Anthropogenic forcing"
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Articoli di riviste sul tema "Anthropogenic forcing"
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Sexton, David M. H., Howard Grubb, Keith P. Shine e Chris K. Folland. "Design and Analysis of Climate Model Experiments for the Efficient Estimation of Anthropogenic Signals". Journal of Climate 16, n. 9 (1 maggio 2003): 1320–36. http://dx.doi.org/10.1175/1520-0442-16.9.1320.
Testo completoAbstract (sommario):
Abstract Presented herein is an experimental design that allows the effects of several radiative forcing factors on climate to be estimated as precisely as possible from a limited suite of atmosphere-only general circulation model (GCM) integrations. The forcings include the combined effect of observed changes in sea surface temperatures, sea ice extent, stratospheric (volcanic) aerosols, and solar output, plus the individual effects of several anthropogenic forcings. A single linear statistical model is used to estimate the forcing effects, each of which is represented by its global mean radiative forcing. The strong colinearity in time between the various anthropogenic forcings provides a technical problem that is overcome through the design of the experiment. This design uses every combination of anthropogenic forcing rather than having a few highly replicated ensembles, which is more commonly used in climate studies. Not only is this design highly efficient for a given number of integrations, but it also allows the estimation of (nonadditive) interactions between pairs of anthropogenic forcings. The simulated land surface air temperature changes since 1871 have been analyzed. The changes in natural and oceanic forcing, which itself contains some forcing from anthropogenic and natural influences, have the most influence. For the global mean, increasing greenhouse gases and the indirect aerosol effect had the largest anthropogenic effects. It was also found that an interaction between these two anthropogenic effects in the atmosphere-only GCM exists. This interaction is similar in magnitude to the individual effects of changing tropospheric and stratospheric ozone concentrations or to the direct (sulfate) aerosol effect. Various diagnostics are used to evaluate the fit of the statistical model. For the global mean, this shows that the land temperature response is proportional to the global mean radiative forcing, reinforcing the use of radiative forcing as a measure of climate change. The diagnostic tests also show that the linear model was suitable for analyses of land surface air temperature at each GCM grid point. Therefore, the linear model provides precise estimates of the space–time signals for all forcing factors under consideration. For simulated 50-hPa temperatures, results show that tropospheric ozone increases have contributed to stratospheric cooling over the twentieth century almost as much as changes in well-mixed greenhouse gases.
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Polson, Debbie, Gabriele C. Hegerl, Xuebin Zhang e Timothy J. Osborn. "Causes of Robust Seasonal Land Precipitation Changes*". Journal of Climate 26, n. 17 (23 agosto 2013): 6679–97. http://dx.doi.org/10.1175/jcli-d-12-00474.1.
Testo completoAbstract (sommario):
Abstract Historical simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5) archive are used to calculate the zonal-mean change in seasonal land precipitation for the second half of the twentieth century in response to a range of external forcings, including anthropogenic and natural forcings combined (ALL), greenhouse gas forcing, anthropogenic aerosol forcing, anthropogenic forcings combined, and natural forcing. These simulated patterns of change are used as fingerprints in a detection and attribution study applied to four different gridded observational datasets of global land precipitation from 1951 to 2005. There are large differences in the spatial and temporal coverage in the observational datasets. Yet despite these differences, the zonal-mean patterns of change are mostly consistent except at latitudes where spatial coverage is limited. The results show some differences between datasets, but the influence of external forcings is robustly detected in March–May, December–February, and for annual changes for the three datasets more suitable for studying changes. For June–August and September–November, external forcing is only detected for the dataset that includes only long-term stations. Fingerprints for combinations of forcings that include the effect of greenhouse gases are similarly detectable to those for ALL forcings, suggesting that greenhouse gas influence drives the detectable features of the ALL forcing fingerprint. Fingerprints of only natural or only anthropogenic aerosol forcing are not detected. This, together with two-fingerprint results, suggests that at least some of the detected change in zonal land precipitation can be attributed to human influences.
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Beenstock, M., Y. Reingewertz e N. Paldor. "Polynomial cointegration tests of anthropogenic impact on global warming". Earth System Dynamics Discussions 3, n. 2 (16 luglio 2012): 561–96. http://dx.doi.org/10.5194/esdd-3-561-2012.
Testo completoAbstract (sommario):
Abstract. We use statistical methods for nonstationary time series to test the anthropogenic interpretation of global warming (AGW), according to which an increase in atmospheric greenhouse gas concentrations raised global temperature in the 20th century. Specifically, the methodology of polynomial cointegration is used to test AGW since during the observation period (1880–2007) global temperature and solar irradiance are stationary in 1st differences whereas greenhouse gases and aerosol forcings are stationary in 2nd differences. We show that although these anthropogenic forcings share a common stochastic trend, this trend is empirically independent of the stochastic trend in temperature and solar irradiance. Therefore, greenhouse gas forcing, aerosols, solar irradiance and global temperature are not polynomially cointegrated. This implies that recent global warming is not statistically significantly related to anthropogenic forcing. On the other hand, we find that greenhouse gas forcing might have had a temporary effect on global temperature.
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Penner, J. E., Y. Chen, M. Wang e X. Liu. "Possible influence of anthropogenic aerosols on cirrus clouds and anthropogenic forcing". Atmospheric Chemistry and Physics Discussions 8, n. 4 (22 luglio 2008): 13903–42. http://dx.doi.org/10.5194/acpd-8-13903-2008.
Testo completoAbstract (sommario):
Abstract. Cirrus clouds have a net warming effect on the atmosphere and cover about 30% of the Earth's area. Aerosol particles initiate ice formation in the upper troposphere through modes of action that include homogeneous freezing of solution droplets, heterogeneous nucleation on solid particles immersed in a solution, and deposition nucleation of vapor onto solid particles. Here, we examine the possible change in ice number concentration from anthropogenic soot originating from surface sources of fossil fuel and biomass burning, from anthropogenic sulfate aerosols, and from aircraft that deposit their aerosols directly in the upper troposphere. We find that fossil fuel and biomass burning soot aerosols exert a radiative forcing of −0.68 to 0.01 Wm−2 while anthropogenic sulfate aerosols exert a forcing of −0.01 to 0.18 Wm−2. Our calculations show that the sign of the forcing by aircraft soot depends on the model configuration and can be both positive or negative, ranging from −0.16 to 0.02 Wm−2. The magnitude of the forcing in cirrus clouds can be comparable to the forcing exerted by anthropogenic aerosols on warm clouds, but this forcing has not been included in past assessments of the total anthropogenic radiative forcing of climate.
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Hansen, J., M. Sato, A. Lacis e R. Ruedy. "The missing climate forcing". Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 352, n. 1350 (28 febbraio 1997): 231–40. http://dx.doi.org/10.1098/rstb.1997.0018.
Testo completoAbstract (sommario):
Observed climate change is consistent with radiative forcings on several time–scales for which the dominant forcings are known, ranging from the few years after a large volcanic eruption to glacial–to–interglacial changes. In the period with most detailed data, 1979 to the present, climate observations contain clear signatures of both natural and anthropogenic forcings. But in the full period since the industrial revolution began, global warming is only about half of that expected due to the principal forcing, increasing greenhouse gases. The direct radiative effect of anthropogenic aerosols contributes only little towards resolving this discrepancy. Unforced climate variability is an unlikely explanation. We argue on the basis of several lines of indirect evidence that aerosol effects on clouds have caused a large negative forcing, at least −1 Wm −2 , which has substantially offset greenhouse warming. The tasks of observing this forcing and determining the microphysical mechanisms at its basis are exceptionally difficult, but they are essential for the prognosis of future climate change.
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Knutson, T. R., T. L. Delworth, K. W. Dixon, I. M. Held, J. Lu, V. Ramaswamy, M. D. Schwarzkopf, G. Stenchikov e R. J. Stouffer. "Assessment of Twentieth-Century Regional Surface Temperature Trends Using the GFDL CM2 Coupled Models". Journal of Climate 19, n. 9 (1 maggio 2006): 1624–51. http://dx.doi.org/10.1175/jcli3709.1.
Testo completoAbstract (sommario):
Abstract Historical climate simulations of the period 1861–2000 using two new Geophysical Fluid Dynamics Laboratory (GFDL) global climate models (CM2.0 and CM2.1) are compared with observed surface temperatures. All-forcing runs include the effects of changes in well-mixed greenhouse gases, ozone, sulfates, black and organic carbon, volcanic aerosols, solar flux, and land cover. Indirect effects of tropospheric aerosols on clouds and precipitation processes are not included. Ensembles of size 3 (CM2.0) and 5 (CM2.1) with all forcings are analyzed, along with smaller ensembles of natural-only and anthropogenic-only forcing, and multicentury control runs with no external forcing. Observed warming trends on the global scale and in many regions are simulated more realistically in the all-forcing and anthropogenic-only forcing runs than in experiments using natural-only forcing or no external forcing. In the all-forcing and anthropogenic-only forcing runs, the model shows some tendency for too much twentieth-century warming in lower latitudes and too little warming in higher latitudes. Differences in Arctic Oscillation behavior between models and observations contribute substantially to an underprediction of the observed warming over northern Asia. In the all-forcing and natural-only forcing runs, a temporary global cooling in the models during the 1880s not evident in the observed temperature records is volcanically forced. El Niño interactions complicate comparisons of observed and simulated temperature records for the El Chichón and Mt. Pinatubo eruptions during the early 1980s and early 1990s. The simulations support previous findings that twentieth-century global warming has resulted from a combination of natural and anthropogenic forcing, with anthropogenic forcing being the dominant cause of the pronounced late-twentieth-century warming. The regional results provide evidence for an emergent anthropogenic warming signal over many, if not most, regions of the globe. The warming signal has emerged rather monotonically in the Indian Ocean/western Pacific warm pool during the past half-century. The tropical and subtropical North Atlantic and the tropical eastern Pacific are examples of regions where the anthropogenic warming signal now appears to be emerging from a background of more substantial multidecadal variability.
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Hao, Xin, Shengping He, Huijun Wang e Tingting Han. "Quantifying the contribution of anthropogenic influence to the East Asian winter monsoon in 1960–2012". Atmospheric Chemistry and Physics 19, n. 15 (7 agosto 2019): 9903–11. http://dx.doi.org/10.5194/acp-19-9903-2019.
Testo completoAbstract (sommario):
Abstract. The East Asian winter monsoon (EAWM) is greatly influenced by many factors that can be classified as anthropogenic forcing and natural forcing. Here we explore the contribution of anthropogenic influence to the change in the EAWM over the past decades. Under all forcings observed during 1960–2013 (All-Hist run), the atmospheric general circulation model is able to reproduce the climatology and variability of the EAWM-related surface air temperature and 500 hPa geopotential height and shows a statistically significant decreasing EAWM intensity with a trend coefficient of ∼-0.04 yr−1, which is close to the observed trend. By contrast, the simulation, which is driven by the same forcing as the All-Hist run but with the anthropogenic contribution to them removed, shows no decreasing trend in the EAWM intensity. By comparing the simulations under two different forcing scenarios, we further reveal that the responses of the EAWM to the anthropogenic forcing include a rise of 0.6∘ in surface air temperature over East Asia as well as weakening of the East Asian trough, which may result from the poleward expansion and intensification of the East Asian jet forced by the change in temperature gradient in the troposphere. Additionally, compared with the simulation without anthropogenic forcing, the frequency of strong (weak) EAWM occurrence is reduced (increased) by 45 % (from 0 to 10/7). These results indicate that the weakening of the EAWM during 1960–2013 may be mainly attributed to the anthropogenic influence.
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Penner, J. E., Y. Chen, M. Wang e X. Liu. "Possible influence of anthropogenic aerosols on cirrus clouds and anthropogenic forcing". Atmospheric Chemistry and Physics 9, n. 3 (3 febbraio 2009): 879–96. http://dx.doi.org/10.5194/acp-9-879-2009.
Testo completoAbstract (sommario):
Abstract. Cirrus clouds have a net warming effect on the atmosphere and cover about 30% of the Earth's area. Aerosol particles initiate ice formation in the upper troposphere through modes of action that include homogeneous freezing of solution droplets, heterogeneous nucleation on solid particles immersed in a solution, and deposition nucleation of vapor onto solid particles. Here, we examine the possible change in ice number concentration from anthropogenic soot originating from surface sources of fossil fuel and biomass burning, from anthropogenic sulfate aerosols, and from aircraft that deposit their aerosols directly in the upper troposphere. We use a version of the aerosol model that predicts sulfate number and mass concentrations in 3-modes and includes the formation of sulfate aerosol through homogeneous binary nucleation as well as a version that only predicts sulfate mass. The 3-mode version best represents the Aitken aerosol nuclei number concentrations in the upper troposphere which dominated ice crystal residues in the upper troposphere. Fossil fuel and biomass burning soot aerosols with this version exert a radiative forcing of −0.3 to −0.4 Wm−2 while anthropogenic sulfate aerosols and aircraft aerosols exert a forcing of −0.01 to 0.04 Wm−2 and −0.16 to −0.12 Wm−2, respectively, where the range represents the forcing from two parameterizations for ice nucleation. The sign of the forcing in the mass-only version of the model depends on which ice nucleation parameterization is used and can be either positive or negative. The magnitude of the forcing in cirrus clouds can be comparable to the forcing exerted by anthropogenic aerosols on warm clouds, but this forcing has not been included in past assessments of the total anthropogenic radiative forcing of climate.
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Baker, Hugh S., Tim Woollings e Cheikh Mbengue. "Eddy-Driven Jet Sensitivity to Diabatic Heating in an Idealized GCM". Journal of Climate 30, n. 16 (agosto 2017): 6413–31. http://dx.doi.org/10.1175/jcli-d-16-0864.1.
Testo completoAbstract (sommario):
The eddy-driven jet is studied using a dry idealized model to determine its sensitivity to thermal forcings. The jet latitude, speed, and variability are investigated under a series of Gaussian patch thermal forcing simulations applied systematically on a latitude–sigma grid in the troposphere. This work builds on previous studies by isolating the responses of the jet speed and latitude as opposed to combining them into a single annular mode index. It also explores the sensitivity of the jet to much smaller spatial heatings rather than applying forcing patterns to simulate anthropogenic climate change, as the size and magnitude of the forcings due to anthropogenic climate change are uncertain. The jet speed and latitude are found to have different sensitivity distributions from each other, which also vary between summer and winter. A simple mechanistic understanding of these sensitivities is presented by considering how the individual thermal forcings modify mean isentropic surfaces. In the cases analyzed, the jet response to forcing scales approximately linearly with the strength of the forcing and when forcings are applied in combination. The findings show a rich latitude–pressure distribution of jet sensitivities to thermal forcings, which will aid interpretation of jet responses in a changing climate. Furthermore, they highlight the areas where uncertainty needs to be reduced in the size and position of expected anthropogenic forcings, in order that the uncertainty in changes of the eddy-driven jet can be reduced.
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CHARLSON, R. J., S. E. SCHWARTZ, J. M. HALES, R. D. CESS, J. A. COAKLEY, J. E. HANSEN e D. J. HOFMANN. "Climate Forcing by Anthropogenic Aerosols". Science 255, n. 5043 (24 gennaio 1992): 423–30. http://dx.doi.org/10.1126/science.255.5043.423.
Testo completoTesi sul tema "Anthropogenic forcing"
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Acosta, Navarro Juan Camilo. "Historical anthropogenic radiative forcing of changes in biogenic secondary organic aerosol". Licentiate thesis, Stockholms universitet, Institutionen för miljövetenskap och analytisk kemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-123188.
Testo completoAbstract (sommario):
Human activities have lead to changes in the energy balance of the Earth and the global climate. Changes in atmospheric aerosols are the second largest contributor to climate change after greenhouse gases since 1750 A.D. Land-use practices and other environmental drivers have caused changes in the emission of biogenic volatile organic compounds (BVOCs) and secondary organic aerosol (SOA) well before 1750 A.D, possibly causing climate effects through aerosol-radiation and aerosol-cloud interactions. Two numerical emission models LPJ-GUESS and MEGAN were used to quantify the changes in aerosol forming BVOC emissions in the past millennium. A chemical transport model of the atmosphere (GEOS-Chem-TOMAS) was driven with those BVOC emissions to quantify the effects on radiation caused by millennial changes in SOA. The specific objectives of this licentiate thesis are: 1) to understand what drove the changes in aerosol-forming BVOC emissions (i.e. isoprene, monoterpenes and sesquiterpenes) and to quantify these changes; 2) to calculate for the first time the combined historical aerosol direct and aerosol-cloud albedo effects on radiation from changing BVOC emissions through SOA formation; 3) to investigate how important the biological climate feedback associated to BVOC emissions and SOA formation is from a global climate perspective. We find that global isoprene emissions decreased after 1800 A.D. by about 12% - 15%. This decrease was dominated by losses of natural vegetation, whereas monoterpene and sesquiterpene emissions increased by about 2% - 10%, driven mostly by rising surface air temperatures. From 1000 A.D. to 1800 A.D, isoprene, monoterpene and sesquiterpene emissions decline by 3% - 8% driven by both, natural vegetation losses, and the moderate global cooling between the medieval climate anomaly and the little ice age. The millennial reduction in BVOC emissions lead to a 0.5% to 2% reduction in climatically relevant aerosol particles (> 80 nm) and cause a direct radiative forcing between +0.02 W/m² and +0.07 W/m², and an indirect radiative forcing between -0.02 W/m² and +0.02 W/m². The suggested biological climate feedback seems to be too small to have observable consequences on the global climate in the recent past.
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Speranza, Alessandra Olga Maria. "Solar and anthropogenic forcing of late-Holocene vegetation changes in the Czech Giant Mountains". [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/84035.
Testo completo
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Kemena, Tronje Peer [Verfasser]. "Assessment of Feedbacks in the Earth System under Anthropogenic Forcing: Two Case Studies / Tronje Peer Kemena". Kiel : Universitätsbibliothek Kiel, 2018. http://d-nb.info/1153401169/34.
Testo completo
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Haywood, James Matthew. "Model investigations into the radiative forcing of climate by anthropogenic emissions of sulphate and soot aerosol". Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283234.
Testo completo
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Bistinas, Ioannis. "Global interactions between fire and vegetation, human activities and climate". Doctoral thesis, ISA-UL, 2016. http://hdl.handle.net/10400.5/12022.
Testo completoAbstract (sommario):
Doutoramento em Engenharia Florestal - Instituto Superior de Agronomia - ULVegetation fires are an important component of the earth’s system land processes and have a significant impact on the vegetation and CO2 dynamics. The global fire patterns are not thoroughly explored and the drivers of fire regimes in global scale are interconnected. However, several modelling assumptions are contradicted by exploring those relationships partially. At global scale, fire extent is fuel limited, with climatic variables showing both positive and negative influence on fuel moisture conditions, and humans showing a negative net effect. When isolating the influence of population density and assuming spatial nonstationarity, the human impact is very detailed and reflects the main land use activities with emphasis on cropland and rangeland management at continental scale. The footprint of fire into the Earth system can be measured in terms of radiative forcing from pre and post-fire albedo changes, with the forest biomes driving the extremes on annual basis. Additionally this thesis explores the patterns and the trends of contemporary fire activity. Contrary to previous studies, the results show non-monotonic patterns at grid cell level. The findings of this thesis give a better insight into the spatial variability and the controls of fire at global scale using satellite derived datasets with a focus to the anthropogenic land use activities
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Leupold, Maike [Verfasser], Miriam Akademischer Betreuer] Pfeiffer, Peter [Akademischer Betreuer] [Kukla e Jens [Akademischer Betreuer] Zinke. "Coral-based climate reconstructions in the central and western Indian Ocean from the Holocene to the present-day : orbital forcing, internal variability and anthropogenic disturbances / Maike Leupold ; Miriam Pfeiffer, Peter Kukla, Jens Zinke". Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1221697366/34.
Testo completo
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Forest, Chris Eliot, Peter H. Stone e Andrei P. Sokolov. "Estimated PDFs of Climate System Properties Including Natural and Anthropogenic Forcings". MIT Joint Program on the Science and Policy of Global Change, 2005. http://hdl.handle.net/1721.1/29791.
Testo completoAbstract (sommario):
We present revised probability density functions (PDF) for climate system properties (climate sensitivity, rate of deep-ocean heat uptake, and the net aerosol forcing strength) that include the effect on 20th century temperature changes of natural as well as anthropogenic forcings. The additional natural forcings, primarily the cooling by volcanic eruptions, affect the PDF by requiring a higher climate sensitivity and a lower rate of deep-ocean heat uptake to reproduce the observed temperature changes. The estimated 90% range of climate sensitivity is 2.4 to 9.2 K. The net aerosol forcing strength for the 1980s decade shifted towards positive values to compensate for the now included volcanic forcing with 90% bounds of -0.7 to -0.16 W/m2. The rate of deep-ocean heat uptake is also reduced with the effective diffusivity, Kv, ranging from 0.25 to 7.3 cm2/s. This upper bound implies that many coupled atmosphere-ocean GCMs mix heat into the deep ocean (below the mixed layer) too efficiently.Abstract in HTML and technical report in PDF available on the Massachusetts Institute of Technology Joint Program on the Science and Policy of Global Change website (http://mit.edu/globalchange/www/).
This work was supported in part by the NOAA Climate Change Data and Detection Program with support from DOE, the Joint Program on the Science and Policy of Global Change at MIT, and the Office of Science (BER) DOE Grant No.DE-FG02-93ER61677.
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Caillet, Justine. "Contribution de la calotte Antarctique au niveau des mers du 19ème au 21ème siècle et liens avec le forçage anthropique". Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALU024.
Testo completoAbstract (sommario):
Bien qu’historiquement inattendu, la calotte Antarctique contribue à l’élévation du niveau des mers depuis plusieurs décennies. Les satellites révèlent que la calotte perd de la masse via la fonte massive induite par l’océan au droit des terminaisons flottantes de ses glaciers, notamment dans les secteurs d’Amundsen et d’Aurora. Le rôle du forçage anthropique dans cette fonte reste néanmoins largement méconnu en raison de la variabilité naturelle, très présente dans la région, et de la durée d’observations relativement restreinte.L’intrusion des eaux profondes circumpolaires relativement chaudes aux abords de la calotte en mer d’Amundsen est avérée depuis le début des relevés en 1994 et l’étude des sédiments suggère que plusieurs glaciers ont subi un retrait de leur ligne d’échouage depuis les années 40. Néanmoins, ces données ne permettent pas d’arbitrer si les conditions pré-industrielles sont compatibles avec des conditions océaniques froides ou chaudes en mer d’Amundsen ou si cette dernière a basculé dans un état chaud tardivement en raison des changements induits par le forçage anthropique. A l’aide d’un ensemble de simulations océaniques du secteur d’Amundsen avec différentes perturbations idéalisées des flux atmosphériques, nous montrons que les conditions pré-industrielles peuvent être associées, au moins de manière intermittente, avec des conditions froides en mer d’Amundsen et de faibles taux de fonte. A l’échelle multi-décennale, les transitions entre deux états résultent principalement des changements des flux de flottabilité en surface qui affectent la stratification thermohaline en modulant la production nette de glace de mer.Pour autant, si ces premiers résultats sont compatibles avec la thèse d’une influence anthropique, ils ne permettent pas d’écarter la thèse de l’influence de la variabilité interne basse fréquence, très marquée dans la région. Un second volet s’attache donc à caractériser l’effet de cette variabilité sur la perte de masse future de l’Antarctique. Cette étude est fondée sur un ensemble de simulations de contribution de la calotte au niveau des mers, d’ici 2100 sous le scénario médian SSP2-4.5, issu d’un modèle de calotte forcé par plusieurs membres de trois modèles climatiques. Nos expériences montrent que la variabilité interne affecte la contribution de l’Antarctique d’ici la fin du siècle de plus de 45% à 93% selon le modèle climatique, alors que leur représentation de la variabilité interne, à la fois océanique et atmosphérique, est certainement sous-estimée. L’influence de la variabilité atmosphérique prédomine et les secteurs d’Amundsen et d’Aurora, siège des principales pertes actuelles, sont les secteurs les plus affectés. Nos résultats suggèrent que l’impact de la variabilité interne sur l’évolution de la calotte doit être systématiquement exploré via l’utilisation de plusieurs membres climatiques.La tentative d’identification des rôles respectifs des influences anthropique et naturelle dans les pertes de masses observées dans les régions d’Amundsen et d'Aurora parachève ces travaux. A cette fin, nous reconstruisons, via une méthode originale d’initialisation, des ensembles d'évolutions de la calotte depuis 1850 avec et sans forçage anthropique pour sept membres d’un même modèle climatique. Comme escompté lors des deux premières phases d’étude, les trajectoires historiques sont impactées par la variabilité interne et certains membres climatiques permettent l’obtention d’états pré-industriels froids par intermittence en mer d'Amundsen. La détection du signal anthropique est ensuite estimée en comparant les trajectoires avec et sans forçage anthropique.Ces travaux ouvrent la voie (i) à la détection/attribution des changements de masse de la calotte et (ii) à l'intégration des modèles de calottes au sein des modèles de climat en proposant une méthodologie d'initialisation de la calotte dès l'ère pré-industrielleThe Antarctic Ice Sheet has contributed to global sea level rise over the last few decades, which was historically unexpected. Satellites indicate that the ice sheet is losing mass through massive ocean-induced melting beneath the floating ice shelves, particularly in the Amundsen and Aurora sectors. Nevertheless, the role of anthropogenic forcing remains largely unclear due to the natural climate variability, which is particularly strong in this region, as well as the relatively short duration of observations.The intrusion of relatively warm circumpolar deep waters beneath the ice shelves in the Amundsen Sea has been observed since the first records in 1994, and the analysis of sediments suggests that several glaciers have experienced a retreat of their grounding line since the 1940s. However, these data do not allow any assessment of whether pre-industrial conditions were compatible with cold or warm oceanic conditions in the Amundsen Sea, or whether the Amundsen Sea switched into a warm state later due to changes triggered by anthropogenic forcing. Using a set of ocean simulations of the Amundsen Sea with various idealised perturbations of atmospheric fluxes, we show that pre-industrial conditions may be associated, at least intermittently, with cold conditions and low melt rates. On multi-decadal timescales, transitions between warm and cold states are primarily driven by changes in surface buoyancy fluxes, which modify thermohaline stratification through the modulation of net sea-ice production.Although these first results suggest a possible anthropogenic influence, they do not rule out the influence of the strong low-frequency internal climate variability. Hence, the second part of the project focuses on the impact of this variability on future Antarctic mass loss. This work is based on a set of simulations of the ice-sheet contribution to sea level rise, by 2100 under the SSP2-4.5 mid-range scenario, generated from an ice-sheet model forced with several members of three climate models. Our experiments show that internal variability affects the Antarctic contribution to sea level rise by the end of the century by more than 45% to 93% depending on the climate model, even though both oceanic and atmospheric internal variability are probably underestimated. The influence of atmospheric variability prevails and the Amundsen and Aurora sectors, which are currently experiencing the largest losses, are the most affected. Our results suggest that the impact of internal variability on the ice-sheet changes should be systematically explored using several climate members.Finally, we attempt to identify the relative roles of anthropogenic and natural influences in the observed mass losses in the Amundsen and Aurora regions. For this purpose, we use an original initialisation method to reconstruct sets of ice-sheet changes since 1850, with and without anthropogenic forcing, for seven members of a single climate model. As expected from the first two study phases, the historical trajectories are sensitive to internal variability, and some climate model members enable intermittent cold pre-industrial states in the Amundsen Sea. The detection of the anthropogenic signal is then evaluated through the comparison of trajectories with and without anthropogenic forcing.This work paves the way for (i) the detection/attribution of ice-sheet mass changes and (ii) for integrating ice-sheet models into climate models, by providing an initialisation method to initialise the ice sheet from the pre-industrial era
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Simonneau, Anaëlle. "Empreintes climatiques et anthropiques sur le détritisme holocène : étude multiparamètres et intégrée de systèmes lacustres d'Europe Occidentale". Phd thesis, Université d'Orléans, 2012. http://tel.archives-ouvertes.fr/tel-00805471.
Testo completoAbstract (sommario):
L'érosion mécanique des surfaces continentales, ou "détritisme", résulte du forçage climatique mais peut être amplifiée par le forçage anthropique. Cette érosion des sols, et sa compréhension, représentent aujourd'hui un questionnement sociétal majeur. Le présent travail s'est donc intéresse aux relations étroites liant climat, Homme et détritisme, dans les environnements continentaux holocènes. Associée à une démarche analytique multiparamètres, couplant quantification et modélisation de l'érosion des sols, l'étude intégrée et la comparaison de différents systèmes lacustres d'Europe occidentale, d'altitude et de piedmont, alpins et pyrénéens, a permis d'obtenir les informations suivantes. A long terme, la bipartition climatique Holocène (Optimum Climatique/Néoglaciaire) s'illustre par une augmentation de l'humidité, généralisée en Europe occidentale, et de l'ordre de 800 mm/an dans les Alpes françaises. Cette transition résulterait d'un relais entre le forçage solaire et le couplage océan/atmosphère. A court terme, l'Holocène est ponctué de périodes plus humides ou plus sèches, synchrones a l'échelle de l'Europe occidentale, et culminant avec le Petit Age Glaciaire. La présence humaine est d'abord mise en évidence dans les systèmes de piedmont et est synchrone a l'échelle des Alpes (Néolithique). Elle parait plus tardive dans les sites de haute altitude (Age du Bronze). L'implantation humaine en altitude et en piedmont est régulée par l'accessibilité aux sites, mais également par des rétroactions climatiques négatives. En piedmont, ces rétroactions négatives ne sont effectives que jusqu'à l'Age du Fer. Si le détritisme est dans un premier temps principalement controlé par le climat, il subit les conséquences de l'anthropisation des le Néolithique dans les Préalpes. Cette anthropisation est limitée aux systèmes de piedmont, ou elle explique jusqu'à 50% de l'érosion des sols, notamment pendant l'Age du Bronze, l'Age du Fer et le dernier siècle.
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Kelley, Colin Patrick. "Recent and future drying of the Mediterranean region: anthropogenic forcing, natural variability and social impacts". Thesis, 2014. https://doi.org/10.7916/D8CR5RFV.
Testo completoAbstract (sommario):
The Mediterranean region has experienced persistent drying since the middle of the 20th Century and global climate models project further drying in the future as a consequence of increasing greenhouse gases. The Mediterranean region is also known to oscillate between decades of relatively wet and dry conditions due to the strong influence of multidecadal North Atlantic Oscillation (NAO). It is therefore of great importance to understand the relationship between forced long-term drying resulting from human influences and those due to natural variability. To this end, we used observations, reanalyses and comprehensive global climate models in this thesis research. The roles of anthropogenic climate change and internal climate variability in causing the Mediterranean region's late 20th Century extended winter drying trend were examined using 20th Century observations as well as 19 coupled climate models from the CMIP3. The drying was strongly influenced by the robust positive trend in the NAO from the 1960s to the 1990s. Model simulations and observations were used to assess the probable relative roles of radiative forcing and internal variability in explaining the circulation trend that drove much of the precipitation change. It was concluded that the radiatively forced trends were a small fraction of the total observed trends. Instead it was argued that the robust trends in the observed NAO and Mediterranean rainfall during this period were largely due to multidecadal internal variability with a small contribution from the external forcing. Differences between the observed and NAO associated precipitation trends are consistent with those expected as a response to radiative forcing. The radiatively forced trends in circulation and precipitation are expected to strengthen in the current century and these results highlight the importance of their contribution to future precipitation changes in the region. The Mediterranean precipitation climatology and trend were further examined by comparing the newest generation of global climate models (CMIP5) used in the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report, to the previous generation (CMIP3) and to observations over the latter half of the 20th Century for both the summer and winter half years. The observed drying trend since 1950 was predominantly due to winter drying, with very little contribution from the summer. However, in the CMIP5 multimodel mean, the precipitation trend since 1950 is evenly divided throughout the seasonal cycle. This may indicate that in observation, multidecadal internal variability, particularly that associated with the NAO, dominates the wintertime trend. An estimate of the observed externally forced trend showed that winter drying dominated in observations but the spatial patterns were grossly similar to the multimodel mean trend. The similarity was particularly robust in the eastern Mediterranean region, indicating a radiatively forced component being stronger there. These results also revealed modest improvement for the CMIP5 multimodel ensemble in representation of the observed six-month winter and summer climatology. We further explored the detailed mechanisms leading to the NAO-associated precipitation change, such as the role of the change in mean circulation versus that of the storm tracks in the regional moisture budget, which had not been investigated previously. We employed a moisture budget analysis using 15 CMIP5 models and the ERA-Interim Reanalysis to investigate the relationship between the NAO and the various moisture budget terms for the six-month winter and summer. Compared with the ERA-Interim, the models performed well in their simulation of the relationship between the naturally varying NAO and the large-scale moisture budget. Our results indicated that the shift in the midlatitude transient eddies induced modest moisture convergence, rather than divergence, over the Mediterranean under a positive NAO. The reduction in precipitation in this region during a positive NAO was dominated by the mean moisture divergence, which opposed the transient contribution. There were significant differences between the patterns of NAO-induced moisture budget anomaly and changes due to external radiative forcing. Under radiative forcing there was enhanced evaporation over the Mediterranean Sea, Italy and eastern Europe and drying by the shift in the wintertime storms over nearly all of Europe and the Mediterranean. Under a positive phase of the NAO, on the other hand, there was modest reduction in evaporation and wetting by the storms over the Mediterranean, and drying over northern Europe. The dependence of the Mediterranean moisture budget on the NAO was similarly explored in the summer half of the year and in this season the models exhibited more disagreement with observations, but otherwise showed the similar results as winter. The stronger anthropogenic induced drying signal over the eastern Mediterranean provided a basis to examine the possible cause and impact of the recent severe and persistent drought in Syria that occurred directly prior to the uprising of 2011. The drought devastated Syrian agriculture, resulting in food shortages, widespread unemployment, the collapse of rural social structure and a mass migration of agricultural refugees to Syria's urban areas. Anger at the government's failure to ameliorate conditions was one spark for the uprising that evolved into civil war. We found that though droughts occur periodically in Syria due to natural causes it is likely that the recent drought was more extreme due to the century long drying trend caused by increased radiative forcing. It was estimated that the anthropogenic trend made a drought of such severity several times more likely. Droughts as persistent as the recent one are projected to be commonplace in a future warmer world.
Libri sul tema "Anthropogenic forcing"
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George C. Marshall Space Flight Center, a cura di. Solar cycle and anthropogenic forcing of surface-air temperature at Armagh Observatory, Northern Ireland. Huntsville], Ala: National Aeronautics and Space Administration, Marshall Space Flight Center, 2010.
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Kelley, Colin Patrick. Recent and future drying of the Mediterranean region: Anthropogenic forcing, natural variability and social impacts. [New York, N.Y.?]: [publisher not identified], 2014.
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Final report on anthropogenic sulfate, clouds, and climate forcing: NASA contract NAGW-3735. [Washington, DC: National Aeronautics and Space Administration, 1997.
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Solar Cycle and Anthropogenic Forcing of Surface-Air Temperature at Armagh Observatory, Northern Ireland. Independently Published, 2020.
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Brook, Barry W., Erle C. Ellis e Jessie C. Buettel. What is the evidence for planetary tipping points? Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198808978.003.0008.
Testo completoAbstract (sommario):
This chapter critically evaluates the likelihood that planet Earth will cross one or more global environmental tipping points, resulting in a degraded state that would be difficult to reverse. Ecological tipping points occur when components of a system change rapidly due an initial forcing that is amplified by positive feedbacks, resulting in a regime shift. The chapter examines the evidence in support of biological and geophysical boundaries that clearly delimit a “safe operating space” for people and biodiversity. For individual ecosystems, abrupt state transitions have been documented. However, apart from the climate system, there is scant evidence (or theoretical justification) to support the view that global aggregates like biodiversity, chemical cycles, or resource extraction have planetary thresholds that define the boundaries of a global safe operating space. Acknowledging the absence of clear evidence for thresholds or boundaries at the global level does not diminish the seriousness of anthropogenic impacts. It does, however, imply that local-scale mitigation actions will be most effective.
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Board on Atmospheric Sciences and Climate, Climate Research Committee, Committee on Radiative Forcing Effects on Climate, Division on Earth and Life Studies e National Research Council. Radiative Forcing of Climate Change: Expanding the Concept and Addressing Uncertainties. National Academies Press, 2005.
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Board on Atmospheric Sciences and Climate, Climate Research Committee, Committee on Radiative Forcing Effects on Climate, Division on Earth and Life Studies e National Research Council. Radiative Forcing of Climate Change: Expanding the Concept and Addressing Uncertainties. National Academies Press, 2005.
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Cook, Kerry H. Climate Change Scenarios and African Climate Change. Oxford University Press, 2018. http://dx.doi.org/10.1093/acrefore/9780190228620.013.545.
Testo completoAbstract (sommario):
Accurate projections of climate change under increasing atmospheric greenhouse gas levels are needed to evaluate the environmental cost of anthropogenic emissions, and to guide mitigation efforts. These projections are nowhere more important than Africa, with its high dependence on rain-fed agriculture and, in many regions, limited resources for adaptation. Climate models provide our best method for climate prediction but there are uncertainties in projections, especially on regional space scale. In Africa, limitations of observational networks add to this uncertainty since a crucial step in improving model projections is comparisons with observations. Exceeding uncertainties associated with climate model simulation are uncertainties due to projections of future emissions of CO2 and other greenhouse gases. Humanity’s choices in emissions pathways will have profound effects on climate, especially after the mid-century.The African Sahel is a transition zone characterized by strong meridional precipitation and temperature gradients. Over West Africa, the Sahel marks the northernmost extent of the West African monsoon system. The region’s climate is known to be sensitive to sea surface temperatures, both regional and global, as well as to land surface conditions. Increasing atmospheric greenhouse gases are already causing amplified warming over the Sahara Desert and, consequently, increased rainfall in parts of the Sahel. Climate model projections indicate that much of this increased rainfall will be delivered in the form of more intense storm systems.The complicated and highly regional precipitation regimes of East Africa present a challenge for climate modeling. Within roughly 5º of latitude of the equator, rainfall is delivered in two seasons—the long rains in the spring, and the short rains in the fall. Regional climate model projections suggest that the long rains will weaken under greenhouse gas forcing, and the short rains season will extend farther into the winter months. Observations indicate that the long rains are already weakening.Changes in seasonal rainfall over parts of subtropical southern Africa are observed, with repercussions and challenges for agriculture and water availability. Some elements of these observed changes are captured in model simulations of greenhouse gas-induced climate change, especially an early demise of the rainy season. The projected changes are quite regional, however, and more high-resolution study is needed. In addition, there has been very limited study of climate change in the Congo Basin and across northern Africa. Continued efforts to understand and predict climate using higher-resolution simulation must be sustained to better understand observed and projected changes in the physical processes that support African precipitation systems as well as the teleconnections that communicate remote forcings into the continent.
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Goswami, B. N., e Soumi Chakravorty. Dynamics of the Indian Summer Monsoon Climate. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.613.
Testo completoAbstract (sommario):
Lifeline for about one-sixth of the world’s population in the subcontinent, the Indian summer monsoon (ISM) is an integral part of the annual cycle of the winds (reversal of winds with seasons), coupled with a strong annual cycle of precipitation (wet summer and dry winter). For over a century, high socioeconomic impacts of ISM rainfall (ISMR) in the region have driven scientists to attempt to predict the year-to-year variations of ISM rainfall. A remarkably stable phenomenon, making its appearance every year without fail, the ISM climate exhibits a rather small year-to-year variation (the standard deviation of the seasonal mean being 10% of the long-term mean), but it has proven to be an extremely challenging system to predict. Even the most skillful, sophisticated models are barely useful with skill significantly below the potential limit on predictability. Understanding what drives the mean ISM climate and its variability on different timescales is, therefore, critical to advancing skills in predicting the monsoon. A conceptual ISM model helps explain what maintains not only the mean ISM but also its variability on interannual and longer timescales.The annual ISM precipitation cycle can be described as a manifestation of the seasonal migration of the intertropical convergence zone (ITCZ) or the zonally oriented cloud (rain) band characterized by a sudden “onset.” The other important feature of ISM is the deep overturning meridional (regional Hadley circulation) that is associated with it, driven primarily by the latent heat release associated with the ISM (ITCZ) precipitation. The dynamics of the monsoon climate, therefore, is an extension of the dynamics of the ITCZ. The classical land–sea surface temperature gradient model of ISM may explain the seasonal reversal of the surface winds, but it fails to explain the onset and the deep vertical structure of the ISM circulation. While the surface temperature over land cools after the onset, reversing the north–south surface temperature gradient and making it inadequate to sustain the monsoon after onset, it is the tropospheric temperature gradient that becomes positive at the time of onset and remains strongly positive thereafter, maintaining the monsoon. The change in sign of the tropospheric temperature (TT) gradient is dynamically responsible for a symmetric instability, leading to the onset and subsequent northward progression of the ITCZ. The unified ISM model in terms of the TT gradient provides a platform to understand the drivers of ISM variability by identifying processes that affect TT in the north and the south and influence the gradient.The predictability of the seasonal mean ISM is limited by interactions of the annual cycle and higher frequency monsoon variability within the season. The monsoon intraseasonal oscillation (MISO) has a seminal role in influencing the seasonal mean and its interannual variability. While ISM climate on long timescales (e.g., multimillennium) largely follows the solar forcing, on shorter timescales the ISM variability is governed by the internal dynamics arising from ocean–atmosphere–land interactions, regional as well as remote, together with teleconnections with other climate modes. Also important is the role of anthropogenic forcing, such as the greenhouse gases and aerosols versus the natural multidecadal variability in the context of the recent six-decade long decreasing trend of ISM rainfall.
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Omstedt, Anders. The Development of Climate Science of the Baltic Sea Region. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.654.
Testo completoAbstract (sommario):
Dramatic climate changes have occurred in the Baltic Sea region caused by changes in orbital movement in the earth–sun system and the melting of the Fennoscandian Ice Sheet. Added to these longer-term changes, changes have occurred at all timescales, caused mainly by variations in large-scale atmospheric pressure systems due to competition between the meandering midlatitude low-pressure systems and high-pressure systems. Here we follow the development of climate science of the Baltic Sea from when observations began in the 18th century to the early 21st century. The question of why the water level is sinking around the Baltic Sea coasts could not be answered until the ideas of postglacial uplift and the thermal history of the earth were better understood in the 19th century and periodic behavior in climate related time series attracted scientific interest. Herring and sardine fishing successes and failures have led to investigations of fishery and climate change and to the realization that fisheries themselves have strongly negative effects on the marine environment, calling for international assessment efforts. Scientists later introduced the concept of regime shifts when interpreting their data, attributing these to various causes. The increasing amount of anoxic deep water in the Baltic Sea and eutrophication have prompted debate about what is natural and what is anthropogenic, and the scientific outcome of these debates now forms the basis of international management efforts to reduce nutrient leakage from land. The observed increase in atmospheric CO2 and its effects on global warming have focused the climate debate on trends and generated a series of international and regional assessments and research programs that have greatly improved our understanding of climate and environmental changes, bolstering the efforts of earth system science, in which both climate and environmental factors are analyzed together.Major achievements of past centuries have included developing and organizing regular observation and monitoring programs. The free availability of data sets has supported the development of more accurate forcing functions for Baltic Sea models and made it possible to better understand and model the Baltic Sea–North Sea system, including the development of coupled land–sea–atmosphere models. Most indirect and direct observations of the climate find great variability and stochastic behavior, so conclusions based on short time series are problematic, leading to qualifications about periodicity, trends, and regime shifts. Starting in the 1980s, systematic research into climate change has considerably improved our understanding of regional warming and multiple threats to the Baltic Sea. Several aspects of regional climate and environmental changes and how they interact are, however, unknown and merit future research.
Capitoli di libri sul tema "Anthropogenic forcing"
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Beniston, Martin. "Anthropogenic Forcing of the Climate System". In Advances in Global Change Research, 73–90. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/1-4020-2346-4_4.
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Schwartz, S. E., e A. Slingo. "Enhanced Shortwave Cloud Radiative Forcing Due To Anthropogenic Aerosols". In Clouds, Chemistry and Climate, 191–236. Berlin, Heidelberg: Springer Berlin Heidelberg, 1996. http://dx.doi.org/10.1007/978-3-642-61051-6_9.
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Kong, Xianghui, Xiaoxin Wang, Huopo Chen, Aihui Wang, Dan Wan, Lianlian Xu, Yue Miao et al. "Mapping Precipitation Changes". In Atlas of Global Change Risk of Population and Economic Systems, 41–65. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-6691-9_3.
Testo completoAbstract (sommario):
AbstractCompared to the observed changes in temperature, the changes in precipitation show more uncertainty (Hartmann et al. 2013). The IPCC AR5 indicated that anthropogenic forcing has contributed to a global-scale intensification of heavy precipitation since the second half of the twentieth century (IPCC 2013) and the intensity of daily precipitation increases more under the higher warming scenarios (Weber et al. 2018).
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Marcos, Marta, Ben Marzeion, Sönke Dangendorf, Aimée B. A. Slangen, Hindumathi Palanisamy e Luciana Fenoglio-Marc. "Internal Variability Versus Anthropogenic Forcing on Sea Level and Its Components". In Space Sciences Series of ISSI, 337–56. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-56490-6_15.
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Bethoux, J. P., M. S. El Boukhary, D. Ruiz-Pino, P. Morin e C. Copin-Montégut. "Nutrient, Oxygen and Carbon Ratios, CO2 Sequestrationand Anthropogenic Forcing in the Mediterranean Sea". In The Mediterranean Sea, 67–86. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/b107144.
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Fousiya, A. A., Javed N. Malik e Supriyo Chakraborty. "Climatic Variability and Anthropogenic Forcing on Marine Ecosystems: Evidence from the Lakshadweep Archipelago". In Coasts, Estuaries and Lakes, 93–108. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-21644-2_6.
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Dameris, M., R. Deckert, M. Dameris e R. Deckert. "Simulation of Long-term Evolution of Stratospheric Dynamics and Chemistry: Role of Natural and Anthropogenic Forcings". In Advances in Global Change Research, 283–91. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-6766-2_19.
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"Anthropogenic forcing". In History and Climate Change, 82–87. Routledge, 2005. http://dx.doi.org/10.4324/9780203995686-17.
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Wang, Hai. "South Asian summer monsoon response to anthropogenic aerosol forcing". In Indian Summer Monsoon Variability, 433–48. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-822402-1.00006-5.
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Whittaker, Robert J., e José María Fernández-Palacios. "Anthropogenic losses and threats to island ecosystems". In Island Biogeography, 290–322. Oxford University PressOxford, 2006. http://dx.doi.org/10.1093/oso/9780198566113.003.0011.
Testo completoAbstract (sommario):
Abstract Throughout our discussions of island ecology and evolution, we have mostly set to one side the significance of humans as shapers of island biogeography. As this chapter will show, this is a questionable practice, as human societies have had a profound influence on island biodiversity in both recent historical and prehistorical time (Morgan and Woods 1986; Johnson and Stattersfield 1990; Groombridge 1992; Pimm et al. 1995). This influence has been manifested in many ways, but the most profound must surely be the extinction of numerous island races and species. Of all the species that have ever lived on the Earth, only a small fraction are alive today. Natural catastrophes, such as volcanic eruptions, meteorite impacts, climate changes, marine transgressions and regressions, in combination with biotic forcing, have been key agents of species extinction in the past. Extinction rates have varied through time, with five phases recognized as particularly intense and widespread events in the fossil record, the so
Atti di convegni sul tema "Anthropogenic forcing"
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Yu, Fangqun, Gan Luo e Xiaoyan Ma. "Ion mediated nucleation and anthropogenic aerosol indirect radiative forcing". In NUCLEATION AND ATMOSPHERIC AEROSOLS: 19th International Conference. AIP, 2013. http://dx.doi.org/10.1063/1.4803360.
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V. Efimov, V., e A. E. Anisimov. "Assesing the climate change in Ukraine in XXI century and the role of anthropogenic forcing". In 9th EAGE International Conference on Geoinformatics - Theoretical and Applied Aspects. European Association of Geoscientists & Engineers, 2010. http://dx.doi.org/10.3997/2214-4609.201402804.
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Kalisoras, Alkiviadis, Aristeidis K. Georgoulias, Dimitris Akritidis, Robert J. Allen, Vaishali Naik e Prodromos Zanis. "Estimating the Effective Radiative Forcing of Anthropogenic Aerosols with the Use of CMIP6 Earth System Models". In COMECAP 2023. Basel Switzerland: MDPI, 2023. http://dx.doi.org/10.3390/environsciproc2023026040.
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Chapanov, Yavor. "LATITUDINAL VARIATIONS OF VOLCANIC SULFATE AND ITS INFLUENCE ON AIR TEMPERATURE". In 22nd SGEM International Multidisciplinary Scientific GeoConference 2022. STEF92 Technology, 2022. http://dx.doi.org/10.5593/sgem2022/4.1/s19.43.
Testo completoAbstract (sommario):
The climate change is strongly affected by the increase of anthropogenic greenhouse gas emissions, such as carbon dioxide, methane, nitrous oxide, and fluorinated gases. Other important atmospheric factors of climate change are stratospheric sulfur aerosols, whose ability to reflect solar radiation back to the space cause cooling effect. Sulfur aerosols have common natural and anthropogenic origin. The volcanos are a major source of particles in the stratosphere, whose lifetime depends on various atmospheric processes � water condensation, rains and winds. Chapanov determines long-term influence of Total Solar Irradiance (TSI) on global volcanic sulfate with periodicity 93-230 years in [1]. A new monthly volcanic forcing dataset had been created by Ammann et al. [8,9]. This dataset presents the seasonal and latitudinal influence on global climate, where negative radiative forcing from volcanic activity is visible in the early 20th century and after 1960. The monthly volcanic data cover the period between 1890 and 1999. The volcanic aerosols are calculated in 64 zonal band with latitude step of 2.8 degrees. The variations of sulfur aerosols over European latitude belt (39.2 N � 56 N) are compared with mean temperature and cycles of solar Indices. Common temperature and sulfur cycles are investigated by means of the Method of Partial Fourier Approximation (PFA). These cycles have good agreement in 11 narrow frequency bands, whose periodicity are between 2.9 and 36.6 years. Possible use of the results in climate study and forecast is discussed.
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Demetrashvili, Demuri, Vepkhia Kukhalashvili, Diana Kvaratskhelia e Aleksandre Surmava. "MARINE FORECAST FOR THE EASTERNMOST PART OF THE BLACK SEA". In GEOLINKS Conference Proceedings. Saima Consult Ltd, 2021. http://dx.doi.org/10.32008/geolinks2021/b1/v3/50.
Testo completoAbstract (sommario):
Modelling and forecasting of dynamic processes and distribution of various substances of anthropogenic and natural origin in coastal and shelf zones of the seas and oceans are of great interest due to the high anthropogenic load of these zones. The aim of this paper is to present some examples of modelling and short-term forecasting of dynamic fields – the current, temperature and salinity in the easternmost Black Sea covering Georgian sector of the Black Sea and adjacent water area using a high-resolution regional model of the Black Sea dynamics. The z-level regional model is based on a full system of ocean hydro-thermodynamics equations and is nested in the basin-scale model of the Black Sea dynamics of Marine Hydrophysical Institute (Sevastopol). To solve the model equation system, a numerical algorithm based on the splitting method is used. Calculations show that circulation processes in the easternmost water area of the Black Sea are characterized by a permanent alternation of different circulation modes with the formation of mesoscale and submesoscale eddies throughout the year, which significantly affect the formation of thermohaline fields; atmospheric wind forcing substantially determines not only the peculiarities of the sea surface horizontal circulation, also the vertical structure of the current field.
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Seleznev, Aleksei, Andrey Gavrilov, Dmitry Mukhin e Alexander Feigin. "Reconstruction of the North Atlantic Oscillation variability and its response to anthropogenic forcing using data-driven stochastic models based on artificial neural networks". In 27th International Symposium on Atmospheric and Ocean Optics, Atmospheric Physics, a cura di Oleg A. Romanovskii e Gennadii G. Matvienko. SPIE, 2021. http://dx.doi.org/10.1117/12.2601900.
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Bitner-Gregersen, Elzbieta M., e Odin Gramstad. "Potential Changes in the Joint Probabilistic Description of the North Atlantic Wave Climate". In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-77592.
Testo completoAbstract (sommario):
Climate changes include natural climate variability and anthropogenic climate change. The latter is leading to global warming and causes changes in metocean conditions. For most marine structures waves represent the dominant environmental load. Therefore, projections of changes of wave characteristics in the 21st century are crucial with respect to design and marine operations. The study investigates potential changes in simultaneous occurrence of significant wave height and spectral wave period in twelve North Atlantic locations by comparing the past and future wave climate. Two IPCC emission scenarios, with radiative forcing of 4.5 and 8.5 W/m2 by the end of the 21st century, have been selected to project future wave conditions. The third generation (3G) wave model WAM with a resolution of 50 km is used to simulate waves. The model has been forced with winds obtained from six CMIP5 climate models for the historical period 1971–2000 and the future period 2071–2100 for the two emissions scenarios. Wave climate projections obtained from one climate model and one ensemble member are presented herein to indicate potential changes in extreme wave characteristics derived from the long-term joint probabilistic model of significant wave height and spectral wave period. Deviations between the past and future wave climate are shown, given attention to the shape of the joint distribution and wave steepness. Uncertainties associated with the presented results are discussed.
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Beltsidis, Ioannis Marios, Chara Georgopoulou, George Dimopoulos e Lefteris Koukoulopoulos. "Concept assessment of a marine carbon capture system for vessel regulatory lifetime extension". In SNAME 8th International Symposium on Ship Operations, Management and Economics. SNAME, 2023. http://dx.doi.org/10.5957/some-2023-043.
Testo completoAbstract (sommario):
Anthropogenic Greenhouse gas emissions increase rapidly throughout years, forcing International Maritime Organization (IMO) to set strict targets on reducing emission in shipping. Carbon Capture (CC) could be one of the solutions within the decarbonization spectrum, given its potential for significant emission reduction. The shipping community is already exploring CC solutions through concept studies, joint development projects and pilot demonstrations. However, no clear window for CC inclusion in CII calculations has been provided by IMO, at the time this paper is written. The objective of this paper is to explore on a concept design level, the capacity of a CC system to improve the CII of a VLCC tanker vessel, to ensure regulatory compliance throughout her life expectancy. Newbuilt and conversion assessment is conducted, accounting for the vessel’s annual operating profile and the benefits of tight heat integration. To calculate the CC performance, a process model is developed of a conventional amine-based carbon capture system integrated to the ship machinery, with and without waste heat recovery (WHR) for CC heat supply. At design conditions all features of CCS and WHR components are determined. At operating conditions, estimates of pumping and compression requirements, reboiler duty and WHR production capacity are evaluated and accounted for in the total footprint of the ship. The results are annualized and compared to baseline no CCS conditions. The associated increase in fuel consumption due to CC use is estimated, along with the CC system’s capital and operational costs.
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Oroud, Ibrahim M. "The Impacts of Anthropogenic and Climate Change Forcings on Water Resources Demands and Availability in Jordan in the Near Future". In Qatar Foundation Annual Research Conference Proceedings. Hamad bin Khalifa University Press (HBKU Press), 2016. http://dx.doi.org/10.5339/qfarc.2016.eepp3380.
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"Climate extremes during the 20th and 21st centuries simulated by the CSIRO Mk3.6 climate model with anthropogenic and natural forcings". In 19th International Congress on Modelling and Simulation. Modelling and Simulation Society of Australia and New Zealand (MSSANZ), Inc., 2011. http://dx.doi.org/10.36334/modsim.2011.f5.wong.
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