Floods, Droughts and Global Warming: Rolling the Climate Dice
Abstract
In this study, we find from analyses of projections of 14 CMIP5 models a robust, canonical global response in rainfall characteristics to CO2 greenhouse warming. Under a scenario of 1% increase per year of CO2 emission, the model ensemble projects globally more heavy precipitation (+7×2.4%K-1), less moderate precipitation (-2.5×0.6%K-1), more light precipitation (+1.8×1.3%K-1), and increased length of dry (no-rain) periods (+4.7×2.1%K-1). Regionally, a majority of the models project a consistent response with more heavy precipitation over climatologically wet regions of the deep tropics especially the equatorial Pacific Ocean and the Asian monsoon regions, and more dry periods over the land areas of the subtropics and the tropical marginal convective zones. Changes in the global circulation associated with the precipitation changes include a narrowing and deepening of convective zone, a rise of the center of gravity and acceleration of the upper branch of the Hadley circulation, an expansion of the subtropics and a poleward shift of the jetstream. Our results suggest that increased risks of severe floods and droughts worldwide induced by increased CO2 emission is the manifestation of a canonical response of the global rainfall system in association with a re-adjustment of the global circulation system, in a competition for increased availability of atmospheric moisture from global warming.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMGC44C..03L
- Keywords:
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- 1620 GLOBAL CHANGE Climate dynamics;
- 1610 GLOBAL CHANGE Atmosphere;
- 1655 GLOBAL CHANGE Water cycles