6533b836fe1ef96bd12a1b2c

RESEARCH PRODUCT

Climats tropicaux d'aujourd'hui à demain : variabilité et changements

subject

description

Present and future tropical climates : their climate variability and their climate changes The oriffttality of tropical climates is re-examined under the light of climate variability and climate change, both present and future . The interannual variability of rainfall is on average larger in the tropics than in the extra-tropics, but it is also spatially more contrasted. Human communities have often responded to this constraint through efficient coping strategies. The regions showing the most variable climate do not necessarily have lower population densities, an indication that in the long run variability is not decisive. However, the recent demographic growth of these regions is often lower, suggesting a greater vulnerability. Seasonal predictions could be instrumental in reducing this vulnerability. Climate predictability is actually higher in the tropics than in the extra-tropics. Tins arises from the role played by slowly varying boundary conditions, but predictability is region-and season-dependant, as shown in East Africa. The recent evolution (1950-2000) of tropical climates displays a clear warning trend related to the enhanced greenhouse effect. For rainfall however, there are only a few regional-scale changes, more difficult to relate to the anthropogenic global change. Projections of climatic variables associated with the water cycle are also more challenging in the tropics. They need to take into account possible changes in the amplitude of climate variability, a hey issue in terms of societal impacts.