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Nombre de programmes trouvés : 76
Conférences

le (28m6s)

Global Climate Change: Past and Future

My presentation will begin with a review of the now-solid evidence for a human influence on the climate of recent decades. Such evidence includes instrumental measurements available for the past two centuries, paleoclimate observations spanning more than a millennium, and comparisons of the predictions from computer models with observed patterns of climate change. I will then address how the study of paleoclimate can inform our assessments of the potential future impacts of human-induced climate change.
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Conférences

le (17m29s)

Long Term Climate Variability: from Past to Future and from Data to Models

Data show that climate has always changed in the past, sometimes with a larger amplitude than what we experimented for two decades. But the main signatures of the anthopogenic forcing are the speed of the change and its globality. Paleodata at different scales are used to test the realism of climate model simulations and then their ability to simulate climates very different from the present one. They are used also to test impact models for water, forest resources. This talk aims to illustrate how paleoclimatology can bring a lot to global change studies, because it privileges interdisciplinary approaches.
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Conférences

le (17m29s)

Comparison of Simulated Tree-Ring Cellulose d180 at the European Scale

In order to investigate factors involved in the inter-annual variability of d180 in tree ring cellulose (d18OTRC), we simulated the d18OTRC from 1960 to 2001 over Europe. We used 1) simulated climate and water isotope fields of REMOiso, a meso-scale circulation model, 2) hypotheses of the distribution of roots and soil hydrology, and 3) a mechanistic model of oxygen-isotopes in tree ring cellulose (d18OTRC). Sensitivity tests show that relative humidity of the air and soil water d18O contribute differently to the d180 in tree ring cellulose according to regional climate. In the commonly observed hydrological situation, humidity of the air ...
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Conférences

le (11m49s)

Holocene Climatic Changes and Their Effect on Morphodynamics and Sedimentation in Campania

High-resolution paleoclimatic studies (e.g. 18O, 13C, CH4, MS, ect) provide 38 detailed reconstructions of the Holocene climatic variability, but they don’t are unable to provide direct informations about the effects of the climatic changes on landscape and human ecosystems. In order to assess the response of the subaerial geomorphologic/pedo-sedimentary systems to the climatic changes and their potential impact on the ancient human communities, detailed stratigraphical investigations in Campania (southern Italy) have been carried out. In addition to indications provided by litho-pedostratigraphical and geomorphological investigations, the study has recurred to historical, archaeological, and palaeobiological data. Some of the main global cyclical ...
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Conférences

le (31m27s)

From Climate Models to Earth System Models

Complex climate models that describe the evolution of the coupled ocean atmosphere cryosphere system are gradually extended to “non physical” components of the earth system, and account for land vegetation dynamics, ocean biology, global biogeochemistry and atmospheric chemistry. In the future, these models will have to better represent the potential feedbacks with society and therefore to couple the natural bio-physical components with the socio-economic system. The paper will review the present status of complex climate and Earth system models, report some preliminary attempts to include societal aspects, and highlight challenges for future research.
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Conférences

le (24m29s)

Detection and Attribution of Climate Change to Different Causes

According to the last IPCC report, the most part of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations. This statement relies on a long process of demonstration that consisted in evaluating the ability of the successive generations of climate models to reproduce and interpret the climate variability of the last decades. The more and more numerous statistical analyses aiming at detecting and attributing climate change to natural and anthropogenic causes have reinforced the assessment of experts. The recent detection and attribution studies of observed ...
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