Abstract
African rainforests are likely to be vulnerable to changes in temperature and precipitation, yet there has been relatively little research to suggest how the regional climate might respond to global warming. This study presents projections of temperature and precipitation indices of relevance to African rainforests, using global climate model experiments to identify local change as a function of global temperature increase. A multi-model ensemble and two perturbed physics ensembles are used, one with over 100 members. In the east of the Congo Basin, most models (92%) show a wet signal, whereas in west equatorial Africa, the majority (73%) project an increase in dry season water deficits. This drying is amplified as global temperature increases, and in over half of coupled models by greater than 3% per °C of global warming. Analysis of atmospheric dynamics in a subset of models suggests that this could be partly because of a rearrangement of zonal circulation, with enhanced convection in the Indian Ocean and anomalous subsidence over west equatorial Africa, the Atlantic Ocean and, in some seasons, the Amazon Basin. Further research to assess the plausibility of this and other mechanisms is important, given the potential implications of drying in these rainforest regions.
Highlights
Changes in local temperature and precipitation have the potential to affect African rainforests and have led to large ecological shifts on millennial timescales [1]
This study presents projections of temperature and precipitation indices of relevance to African rainforests, using global climate model experiments to identify local change as a function of global temperature increase
The present study aims to explore trends in Central African temperature and precipitation associated with DTg, adding to previous work by comparing Coupled Model Intercomparison Project phase 3 (CMIP3) with two perturbed physics ensembles (PPEs) developed by the Met Office Hadley Centre (MOHC)
Summary
Changes in local temperature and precipitation have the potential to affect African rainforests and have led to large ecological shifts on millennial timescales [1]. Several studies have used the CMIP3 models to investigate the implications of specific DTg thresholds for African precipitation [7] and the impact of these precipitation changes on the potential distribution of humid tropical forests [8] These papers reveal that the increase in precipitation in Central Africa projected by many of the models is enhanced from 28C to 38C to 48C of global warming, suggesting greater potential for rainforest expansion as global warming progresses. For CMIP3 and AO-PPE, changes in temperature, precipitation and MCWD100 for each model grid-point were linearly regressed against global mean temperature increase (DTg), using ordinary least squares and the slope of the regression line (m) used to rstb.royalsocietypublishing.org Phil Trans R Soc B 368: 20120298.
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