D'ailleurs, une excellente référence up-to-date :Envoyé par grafikm_fr
DYNAMICS OF DECADAL CLIMATE VARIABILITY AND IMPLICATIONS FOR ITS PREDICTION (PDF)
ABSTRACT
The temperature record of the last 150 years is characterized by a long-term warming trend, with strong multidecadal variability superimposed. The multidecadal variability is also seen in other (societal important) parameters such as Sahel rainfall or Atlantic hurricane activity. The existence of the multidecadal variability makes climate change detection a challenge, since Global Warming evolves on a similar timescale. The ongoing discussion about a potential anthropogenic signal in the Atlantic hurricane activity is an example. A lot of work was devoted during the last years to understand the dynamics of the multidecadal variability, and external as well as internal mechanisms were proposed. This White Paper focuses on the internal mechanisms relevant to the Atlantic Multidecadal Oscillation/Variability (AMO/V) and the Pacific Decadal Oscillation/Variability (PDO/V). Specific attention is given to the role of the Meridional Overturning Circulation (MOC) in the Atlantic. The implications for decadal predictability and prediction are discussed.Analyses of ocean observations and model simulations by [33] suggest that there have been considerable changes in the thermohaline circulation during the last century. These changes are likely to be the result of natural multidecadal climate variability and are driven by low-frequency variations of the North Atlantic Oscillation (NAO) through changes in Labrador Sea convection (Fig. 5a).
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We expect that the next few decades will be strongly influenced by such multidecadal variations, although the effects of anthropogenic climate change are likely to introduce trends. Some impact of the variations of the thermohaline circulation on the atmosphere has been demonstrated in some studies, so that useful decadal predictions with economic benefit may be possible. However, unpredictable external forcing through strong volcanic eruptions and/or anomalous solar radiation may offset the internal variations and introduce an additional source of uncertainty.Experience gained from Numerical Weather and Seasonal Prediction shows that reduction of systematic bias helps to considerably improve forecast skill. Biases are still large in state-of-the-art climate models. Typical errors in surface air temperature, for instance, can amount up to 10°C in certain regions in individual models.Likewise significant discrepancies to observations exist concerning the variability. Many models, for instance, fail to simulate a realistic El Niño/Southern Oscillation ([31]). Thus it cannot be assumed that current climate models are well suited to realize the full decadal predictability potential.
Non c'est la politique et le capitalisme (y compris poussé par les Verts)
La politique car c'est plus facile de donner une faute "globale" que de donner une responsabilité personnelle, et cela donne bonne conscience. De plus, cela détourne les esprits ("y a tellement de choses à faire") des problèmes "locaux" et purement dépendants de la temporalité des gouvernements.
Le capitalisme car, comme je l'ai dit plus haut, c'est une excellente campagne de marketing pour vendre de nouveaux produits.
Poussé par les Verts car ils ne se rendent même pas compte que grâce à eux les usines et les multinationales tournent à plein régime (les usines d'automobiles pour faire des "voitures vertes", les usines pour "panneaux solaires", les cabinets de consultants de tout poil pour les "bilans éénergétiques" et autres, etc etc etc).
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à part les Oasis.
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