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Impact du changement climatique sur la mousson d'Afrique de l'Ouest

Impact du changement climatique sur la mousson d'Afrique de l'Ouest. Philippe Quirion CNRS CIRED et LMD. Le Sahel est la région qui a connu la plus forte baisse des précipitations au 20 e siècle Source : GIEC 2007, Groupe 1, ch. 3, p. 257 http://ipcc-wg1.ucar.edu/wg1/wg1-report.html.

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Impact du changement climatique sur la mousson d'Afrique de l'Ouest

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  1. Impact du changement climatique sur la mousson d'Afrique de l'Ouest Philippe Quirion CNRS CIRED et LMD

  2. Le Sahel est la région qui a connu la plus forte baisse des précipitations au 20e siècle Source : GIEC 2007, Groupe 1, ch. 3, p. 257 http://ipcc-wg1.ucar.edu/wg1/wg1-report.html

  3. Pluies au Sahel 1920-2003 Source : GIEC 2007 ch. 3 p. 299

  4. La sécheresse au Sahel semble liée à la hausse de la température des océans "The recent drying trend in the semiarid Sahel is attributed to warmer-than-average low-latitude waters around Africa" Giannini, Saravanan & Chang, Science 2005

  5. Le 21e siècle en Afrique de l'Ouest: +2 à +6°C Source : GIEC 2007 groupe 1, ch. 11

  6. Les modèles divergent quant aux précipitations Source : GIEC 2007 Groupe I ch. 11, p. 869

  7. La divergence persiste même si l'on se limite aux "meilleurs" modèles Cook & Vizy, Journal of Climate 2006

  8. La paléoclimatologie : les moussons sont des systèmes fragiles • "Paleoclimatic observations indicate that abrupt decadal- to centennial-scale changes in the regional frequency of tropical cyclones, floods, decadal droughts and the intensity of the African-Asian summer monsoon very likely occurred during the past 10 000 yr. However, the mechanisms behind these abrupt shifts are not well understood, nor have they been thoroughly investigated using current climate models." GIEC 2007 Groupe 1 p. 436 • "Lake sediment and historical documentary evidence indicate that northern Africa and the Sahel region have for a long time experienced substantial droughts lasting from decades to centuries. Although there have been attempts to link these dry periods to solar variations, the evidence is not conclusive." GIEC 2007 Groupe 1 p. 483

  9. Conclusion : comment s'adapter à un changement inconnu ? • New studies confirm that Africa is one of the most vulnerable continents to climate variability and change because of multiple stresses and low adaptive capacity. Some adaptation to current climate variability is taking place, however, this may be insufficient for future changes in climate. (GIEC 2007 groupe 2, SPM, p. 8) • http://www.ipcc.ch/ • http://amma-international.org/

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