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Modeling Rainfall Over Burkina Faso
Ibrahim, B., Karambiri, H., Polcher, J., Yacouba, H. and Ribstein, P. 2014. Changes in rainfall regime over Burkina Faso under the climate change conditions simulated by 5 regional climate models. Climate Dynamics 42: 1363-1381.

The authors write that "with a focus on West Africa, climate models project different trends for the annual rainfall amount over the 21st century," citing Hulme et al. (2001), De wit and Stankiewicz (2006) and Paeth et al. (2009), while further noting that several simulations of the annual rainfall amount over the West African Sahel unfortunately show "a wide range of changes in the annual rainfall amount without any consensus either from the GCMs [Global Climate Models] or from the RCMs [Regional Climate Models]."

What was done
In an attempt to better this situation, Ibrahim et al. analyzed the evolution of the rainfall regime over Burkina Faso, in the West African Sahel, "with regard to the changes in eight characteristics of the rainy season (date of the season onset, date of the end of season, season duration, number of rain days, mean daily rainfall, maximum daily rainfall, annual rainfall amount, and mean dry spell length)."

What was learned
The five researchers report that (1) "the simulated relationship between changed annual rainfall amounts and the number of rain days or their intensity varies strongly from one model to another," that (2) "the climate models' simulations do not show any consensus in the trends of the annual rainfall amount over the West African Sahel during the 21st century, even when they are run under the same climate change scenario at a high spatial resolution," and that (3) "some changes do not correspond to what is observed for the rainfall variability over the last 50 years."

What it means
In light of what they learned, Ibrahim et al. conclude their paper with the statement that it is "unlikely that the uncertainty in rainfall changes projected for West Africa will decrease unless the parameterizations of convection are substantially improved (Grandpeix and Lafore, 2010) or the resolution of the RCM is sufficiently high to simulate some aspects of convection explicitly." And even if the latter two conditions are ultimately met, there is still the possibility that something else might be further foiling the project. Only time will tell ... and we appear to be running out of it.

De Wit, M. and Stankiewicz, J. 2006. Changes in surface water supply across Africa with projected climate change. Science 311: 1917-1921.

Grandpeix, J.Y. and Lafore, J.P. 2010. A density current parameterization coupled with Emanuel's convection scheme. Part I: the models. Journal of the Atmospheric Sciences 67: 881-897.

Hulme, M., Doherty, R., Ngara, T., New, M. and Lister, D. 2001. African climate change: 1900-2100. Climate Research 17: 145-168.

Paeth, H., Born, K., Girmes, R., Podzun, R. and Jacob, D. 2009. Regional climate change in tropical and northern Africa due to greenhouse forcing and land use changes. Journal of Climate 22: 114-132.

Reviewed 21 May 2014