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Africa's Vegetative Future in a CO2-Enriched and Warmer World
Scheiter, S. and Higgins, S.I. 2009. Impacts of climate change on the vegetation of Africa: an adaptive dynamic vegetation modeling approach. Global Change Biology 15: 2224-2246.

The authors write that "recent IPCC projections suggest that Africa will be subject to particularly severe changes in atmospheric conditions" in the years and decades ahead, and that these changes could have equally severe repercussions for its flora and fauna. However, they say that how the continent's "grassland-savanna-forest complex will respond to these changes has rarely been investigated," and that "most studies on global carbon cycles use vegetation models that do not adequately account for the complexity of the interactions that shape the distribution of tropical grasslands, savannas and forests."

What was done
In an attempt to overcome these shortcomings, Scheiter and Higgins developed a new vegetation model -- the adaptive dynamic global vegetation model (aDGVM) -- that employs established sub-models for photosynthesis, respiration, canopy scaling, competition for water, competition for light, reproduction and mortality, and which additionally contains the novel elements of dynamic carbon allocation and phenology functions, as well as a fire model that estimates fire intensity as a function of fuel biomass, fuel moisture and wind speed, and which simulates topkill (stem mortality) as a function of individual tree size and fire intensity, all of which phenomena are related to the individual plant's physiological state and the environmental conditions surrounding it.

What was learned
Forward simulations to the year 2100 suggest, in the words of the two researchers, that "grasslands will spread into the Sahara and into the horn of Africa, such that the total area covered by deserts or bare soil decreases by 5.7%." In addition, they say "it is predicted that 34.6% of today's grasslands are transformed into savannas," and that "45.3% of today's savannas are transformed into deciduous woodlands." As a result, they indicate that "the total biomass stored in each of the biomes increases, with high relative changes in grasslands and savannas (by 256% and 241%, respectively)" and with a 102% increase in tree biomass.

What it means
The CO2- and warming-induced greening of the earth phenomenon, which has been manifest throughout the entire world over the past few decades, seems destined to continue apace throughout the entire 21st century in Africa. Yet increasing air temperatures and CO2 concentrations are the uncontested "twin evils" of the radical environmentalist movement. Apparently -- to use a somewhat less-than-scientific analogy -- these folks just don't have their heads screwed on right. Or if this is not the case ... (you can complete the sentence to your own liking).

Reviewed 18 November 2009