[en] The author states that global warming is not only due to the greenhouse effect, but also to the irresponsibility of decision makers and to the denial of some heads of State because of their scientific ignorance, paranoid mistrust or political interest. In this book, he aims at outlining the necessity to de-compartmentalise knowledge by integrating human sciences (sociology, psychology, politics, philosophy, and so on). He first analyses reasons for and consequences of climate disruption: soil modifications, greenhouse effect, mains sequences of the scientific alarm, role of the IPCC, greenhouse gases, role of human activity. Then, he describes how to act here and now with the world as it is to control effects of climate by suppressing its causes, by extending the range of possible, by addressing the issue of future energy needs, by examining bio-engineering solutions, by implementing actual measures, and by considering territories as spaces for actual solutions, for experimentation and for education

[en] This analysis, based entirely on the results presented in the most recent reports of the IPCC, leads us to highlight several points. It appears first of all that we can, through a very simple algorithm, assess temperature increases by 2100 for a wide variety of scenarios with greenhouse gas mixes that are also diversified in terms of their impact on temperature increases by attributing to each of these gases its share in the expected warming. The relation between this increase in temperature and the cumulative GteqCO₂ over the entire period is: Y= 0.444*Xi/1000, where Xi is the cumulative GteqCO₂ over the relevant period of the gas i. The analysis carried out, which makes it possible to discriminate the responsibility of each of the greenhouse gases in the temperature increase expected from a given emission scenario, reveals the major importance to be attributed to methane emission reductions in the fight against global warming. It is even more necessary to be vigilant to this question because the presentation retained by the IPCC, based on an accounting of different greenhouse gases at 100 years and not at a fixed date (2050 or 2100 for example), largely masks the phenomenon. By reading this figure, decision-makers can very well choose in good faith strategies that are expressed by an emissions scenario respecting the plot of CH₄ emission trajectories, without realizing that the mix of greenhouse gases they have chosen is in fact producing very different results from those expected by 2100. The algorithm that we recommend should avoid this type of confusion and allows the decision makers to assess the expected results of their strategy in relation to the stated objectives. Lastly, in the context of the 2018 Facilitation Dialogue, this tool could help to put more emphasis on, by recognizing at fair value the reduction efforts on CH₄ emissions often undertaken by some countries, in particular the developing world, and whose importance is not recognized today

[en] In a few years or decades, adaptation to climate change has become an essential necessity in the face of an ever-growing constant, that of a very insufficient control of greenhouse gas emissions, which keeps us further and further away from stabilization scenarios proposed by the Paris agreements. The modalities of this adaptation are therefore themselves very constrained. Firstly because it is of course not a question of competing with mitigation actions, but of determining what makes the common denominator of these two approaches. Also because the scale of the territories, which is often that of adaptation, must take into account a complex reality which is also that of the living, of biodiversity and of humans, all of which we have a duty to protect. (author)

[en] There is currently a debate on the ability of the simple Global Warming Potential (GWP) concept to describe adequately the effects of the different gases under different mitigation strategies. Public action to curve down greenhouse gases may target different time scales, and different climate parameters. A recent IPCC expert meeting has concluded that, while GWP is a useful index, defined in a clear and physical manner, and improved by a continuous review process, it has not been designed to address the whole range of policies and is not adequate to deal with some of them. There is a concern about the best way to include the role of short-lived pollution, which is reflected in many of the papers presented at the IPCC Expert Meeting. Focusing again on methane, and depending on the context, the CO₂ equivalent value appear too large or too small, with foreseeable consequences on the negotiations and policies. On one side, the surface temperature of the Earth, at a given time, is largely at equilibrium with the concentration of all greenhouse gases, including methane. As the concentration due to a pulse of methane declines very rapidly with time, the integration concept associated to GWP does not provide a correct assessment of this temperature. It is the reason why a different concept, the Global Temperature Potential (GTP) has been proposed as more suitable for this purpose. A detail computation of the GTP would involve a model of surface temperature evolutions, but the GTP of CH₄ at year T may be approximated as the radiative forcing from the CH₄ concentration that would result from a pulse emission of 1 tonne after T years, compared to that of a pulse of 1 tonne of CO₂ after the same T years. On one side, we may think that GTP is better suited to estimate the impact of methane policies, because one of the reasons why we need short-term actions to curb down methane is precisely the fear of seeing the global earth temperature rising above the 2 deg. C level. On the other side, instantaneous surface temperature is not the only parameter describing climate change. There are other parameters in the climate system that may depend more critically on the integration of the radiative forcing than its instantaneous value. This is probably the case of the deeper ocean thermal expansion, or large ice cap melting, two processes which are essential in producing irreversibility in the climate change. In this paper we wish to address another concern, which has not received much attention while we think it has large implications: the 'pulse' concept is clearly inadequate to describe current mitigation actions and the common practice of policy makers. In fact, almost all the emission mitigation programmes from international and national instances, whether already effective or considered for future action, correspond to emission reductions which should last at least several decades. Furthermore, the national programmes take as an implicit hypothesis that these reduction policies will perpetuate: at the end of a given action, a new reduction action is supposed to begin, at least equally effective, and hopefully more effective. So we have to consider that the mitigation measures we wish to evaluate will most generally perpetuate almost indefinitely. In addition, defining a methane (or CO₂) reduction programme involving new initiatives every year induces a continuous increase of this methane reduction. Opening a debate on a new definition of the GWP is troublesome for at least two reasons: (i) it may undermine international agreements that have been slow to construct; (ii) it may be seen in some cases as an incentive to substitute easier short-term strategies to the absolutely necessary reduction of CO₂ emissions, which carry the dominant and lasting impacts on climate. But CO₂ and CH₄ reductions are not in competition one against the other: they generally concern different economic actors and should be encouraged simultaneously, because we know that we need all possible actions to curb down climate warming. Therefore whatever index we use, we should be fully conscious of its impact on a given type of policies. The aim of the paper is to analyse the consequences of using different metrics on CH₄ mitigation policies. In paragraph 2, we redefine GWP, GTP, and introduce a modified definition of those metrics to assess the relative role of lasting emissions (or reversely, lasting mitigation) rather than pulse emissions (or reversely, pulse mitigation) of CO₂ and CH₄, from a short (2030) to long-term (>2100) perspective. In paragraphs 3, 4 and 5 we review the different methane mitigation options which might be better targeted by a more specific definition of the methane CO₂ equivalent

[en] First and foremost, this book provides a better understanding of what we know and don't know about climate. It provides an insight into the genealogy of the climate issue and climate sciences, and the complexities of model building and climate risk assessment, i.e., into the inner workings of the IPCC reports. It also provides an insider's view of how researchers have been confronted with climate skepticism and the pressures and demands of society, to which they have not always been able to respond. Finally, it provides an opportunity to reflect on the future that awaits us, and what the coming decades hold in store for us, with two historic players in the climate saga

[en] As the next IPCC (Intergovernmental Panel on Climate Change) report is soon to be published, a paleo-climatologist answers few questions about issues related to climate change (recent climate events, slower temperature increase during the past ten years, lessons learned from the previous IPCC report, evolutions of models, remaining opportunities to limit temperature increase to 2 degrees). A second article comments climate modelling improvements (finer description of oceans, atmosphere and ice field, introduction of new mechanisms in IPCC models such as carbon cycle, vegetation evolution, aerosols and atmospheric chemistry, models relying on greenhouse gas emission principles and not on socioeconomic scenarios any longer). A third article outlines that Earth has never been so warm since 1850 and proposes some explanations about the fact that warming has slowed down during the last ten years. A fourth article discusses how greenhouse gas emissions can be reduced, notices that their accounting underestimates the short-term and medium-term impact of methane emission reduction, and stresses the importance of an increased attention to methane emissions

[en] After an introduction which presents various characteristics of the New-Aquitaine region (geography, economy, towns and population, waters, coasts, natural heritage, agriculture and breeding, energy production and consumption, greenhouse gas emissions), this huge report addresses various aspects and issues related to climate changes: relationship between global climate and local climate, memory as a support for a better adaptation to climate change, legal instruments for the adaptation to climate change, environmental health, quality of natural environments, relationship between water availability and climate change, regional energy and energy transition, resources exploited by fisheries and shellfish farming, new forests and new expectations, which agriculture for to-morrow, urban territories and climate stakes, mountain areas, and local participation and citizen empowerment.

[en] This monograph addresses the impacts of climate change in the Aquitaine region by 2030-2050 in order to prepare the adaptation of the main economic sectors. Several fields are addressed: agriculture and wine-growing, forestry, estuaries, coasts and sea resources. The document examines two aspects of climate change due to greenhouse gas emissions: mitigation and adaptation. Two scenarios are studied: a global temperature increase of 2 degrees, and a global temperature increase between 4 and 5 degrees. As examples of this study, this article gives an overview of these issues of mitigation and adaptation in four domains: forests, wine-growing, air quality, and health.

[en] This article presents a book which addresses the impacts of climate change in the Aquitaine region by 2030-2050 in order to prepare the adaptation of the main economic sectors. Several fields are addressed: agriculture and wine-growing, forestry, estuaries, coasts and sea resources. The book examines two aspects of climate change due to greenhouse gas emissions: mitigation and adaptation. Two scenarios are studied: a global temperature increase of 2 degrees, and a global temperature increase between 4 and 5 degrees. As examples of this study, this article gives an overview of these issues of mitigation and adaptation in four domains: forests, wine-growing, air quality, and health

[en] This report proposes a detailed presentation of knowledge on methane and on its role in the atmosphere. The first part addresses methane and the greenhouse effect: general considerations on methane in the atmosphere, radiative properties and importance with respect to the greenhouse effect, methane and future climate change. The second part proposes a presentation of methane sources and sinks. The third part addresses the study of methane fluxes: possible approaches to assess methane fluxes, measurement of atmospheric methane, the issue of atmospheric inversion (an approach to convert atmospheric observations into methane fluxes, lessons learned from atmospheric inversions, perspectives to improve knowledge on methane fluxes). The next chapters discuss the past, present and future evolution of methane in the atmosphere, discuss the carbon equivalence of methane (Kyoto protocol, policies of climate change, global warming power, role of methane, metrics, emission reduction), and comment the current perceivable evolutions, propose some methodological recommendations and actions to be implemented on the short term with no regret