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Nombre de programmes trouvés : 2094
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 (27m2s)

The Impacts of Climate Change on Continental Ecosystems

Climate change will deeply modify the ecophysiological functioningof plants, by creating a set of conditions which could be more favourable (in the sense of biomass production) or not. Among the first, the increase ofatmospheric CO2 will stimulate the photosynthesis (with levels depending upon plants and conditions), with a result of a potential increase in biomass up to 20 % in some cases. Warmer temperatures will also generally be favourable to most of the physiological processes, up to an optimum above which the risk of detrimental or lethal values exists. The (almost) generalized advance in phenology (calendar of development stages) will ...
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Conférences

le (28m58s)

Modelling Forced and Internal Climate Variability During the Last Millennium

At hemispheric scale, the surface temperature is strongly influenced by the 28 variations of the natural (solar and volcanic) and anthropogenic (land-use, sulphate aerosols, greenhouse gas concentrations) forcings. By contrast, at regional scale, the internal variability, which is purely due to the internal dynamics of the climate system, can mask the forced response. As a consequence, before the 20th century, cold or warm periods are rarely global, homogenous phenomena. Furthermore, the response to the forcing could be associated with changes in the frequency of some modes of variability. This interplay between the response of the climate system to the various ...
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Conférences

le (28m50s)

International Negociations on Climate Change: How to Take Advantage of Risk Aversion to Improve the Conditions for the Emergence of a Consensus

Climate change is one of the best examples of global environmental problems. Countries are conscious that they have to find a solution to this global problem at the international level. Negotiations on climate change started more than 15 years ago with the signature of the United Nations Framework Convention on Climate Change. Since then, the process went through a series of conferences and protocols. Part of this process, the Kyoto protocol constitutes a major step since it designed country-specific targets defined in terms of CO2 emissions abatement. The fact is that we should not speak about an international environmental agreement ...
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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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Conférences

le (33m37s)

The Intergovernmental Panel on Climate Change and the Challenges of Climate policy, Equity and Ethics

The 2007 Intergovernmental Panel on Climate Change (IPCC) report provides clear guidance for the greenhouse gas emissions reductions needed to limit global warming to specific targets such as 2 °C above pre-industrial values, as adopted formally by the European Union. Despite the strong scientific consensus found by the IPCC concerning the reality and seriousness of global warming, worldwide emissions of the greenhouse gases that cause climate change continue to increase each year. The nations of the world are still far from agreement on how to act to reduce emissions.
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