Projected Changes in Mean and Extreme Precipitation in Africa under Global Warming. Part I: Southern Africa

Shongwe, M. E.; van Oldenborgh, G. J.; van den Hurk, B. J. J. M.; de Boer, B.; Coelho, C. A. S.; van Aalst, M. K.
July 2009
Journal of Climate;Jul2009, Vol. 22 Issue 13, p3819
Academic Journal
This study investigates likely changes in mean and extreme precipitation over southern Africa in response to changes in radiative forcing using an ensemble of global climate models prepared for the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). Extreme seasonal precipitation is defined in terms of 10-yr return levels obtained by inverting a generalized Pareto distribution fitted to excesses above a predefined high threshold. Both present (control) and future climate precipitation extremes are estimated. The future-to-control climate ratio of 10-yr return levels is then used as an indicator for the likely changes in extreme seasonal precipitation. A Bayesian approach to multimodel ensembling is adopted. The relative weights assigned to each of the model simulations is determined from bias, convergence, and correlation. Using this method, the probable limits of the changes in mean and extreme precipitation are estimated from their posterior distribution. Over the western parts of southern Africa, an increase in the severity of dry extremes parallels a statistically significant decrease in mean precipitation during austral summer months. A notable delay in the onset of the rainy season is found in almost the entire region. An early cessation is found in many parts. This implies a statistically significant shortening of the rainy season. A substantial reduction in moisture influx from the southwestern Indian Ocean during austral spring is projected. This and the preaustral spring moisture deficits are possible mechanisms delaying the rainfall onset in southern Africa. A possible offshore (northeasterly) shift of the tropical–temperate cloud band is consistent with more severe droughts in the southwest of southern Africa and enhanced precipitation farther north in Zambia, Malawi, and northern Mozambique. This study shows that changes in the mean vary on relatively small spatial scales in southern Africa and differ between seasons. Changes in extremes often, but not always, parallel changes in the mean precipitation.


Related Articles

  • A Nonlinear Response of Sahel Rainfall to Atlantic Warming. Neupane, Naresh; Cook, Kerry H. // Journal of Climate;Sep2013, Vol. 26 Issue 18, p7080 

    The response over West Africa to uniform warming of the Atlantic Ocean is analyzed using idealized simulations with a regional climate model. With warming of 1 and 1.5 K, rainfall rates increase by 30%-50% over most of West Africa. With Atlantic warming of 2 K and higher, coastal precipitation...

  • Effects of climate warming on the distributions of invasive Eurasian annual grasses: a South African perspective. Parker-Allie, F.; Musil, C. F.; Thuiller, W. // Climatic Change;May2009, Vol. 94 Issue 1/2, p87 

    Threats posed by Eurasian annual grasses to ecosystem function have received little attention. Therefore, protocols for prioritising these alien annual species and likely future dimensions of their spread are urgently required. Here we modelled these grasses potential distribution and shifts in...

  • Interdecadal change of the controlling mechanisms for East Asian early summer rainfall variation around the mid-1990s. Yim, So-Young; Wang, Bin; Kwon, MinHo // Climate Dynamics;Mar2014, Vol. 42 Issue 5/6, p1325 

    East Asian (EA) summer monsoon shows considerable differences in the mean state and principal modes of interannual variation between early summer (May-June, MJ) and late summer (July-August, JA). The present study focuses on the early summer (MJ) precipitation variability. We find that the...

  • Modelling China's potential maize production at regional scale under climate change. Wei Xiong; Matthews, Robin; Holman, Ian; Lin, Erda; Yinglong Xu // Climatic Change;Dec2007, Vol. 85 Issue 3/4, p433 

    With the continuing warming due to greenhouse gases concentration, it is important to examine the potential impacts on regional crop production spatially and temporally. We assessed China's potential maize production at 50×50 km grid scale under climate change scenarios using modelling...

  • How robust is the long-run relationship between temperature and radiative forcing? Mills, Terence C. // Climatic Change;Jun2009, Vol. 94 Issue 3/4, p351 

    This paper examines the robustness of the long-run, cointegrating, relationship between global temperatures and radiative forcing. It is found that the temperature sensitivity to a doubling of radiative forcing is of the order of 2 ± 1°C. This result is robust across the sample period of...

  • The Role of the Sahara Low in Summertime Sahel Rainfall Variability and Change in the CMIP3 Models. Biasutti, M.; Sobel, A. H.; Camargo, Suzana J. // Journal of Climate;Nov2009, Vol. 22 Issue 21, p5755 

    Projections for twenty-first-century changes in summertime Sahel precipitation differ greatly across models in the third Coupled Model Intercomparison Project (CMIP3) dataset and cannot be explained solely in terms of discrepancies in the projected anomalies in global SST. This study shows that...

  • Effects of Temperature and Precipitation Variability on Snowpack Trends in the Western United States. Hamlet, Alan F.; Mote, Philip W.; Clark, Martyn P.; Lettenmaier, Dennis P. // Journal of Climate;Nov2005, Vol. 18 Issue 21, p4545 

    Recent studies have shown substantial declines in snow water equivalent (SWE) over much of the western United States in the last half century, as well as trends toward earlier spring snowmelt and peak spring streamflows. These trends are influenced both by interannual and decadal-scale climate...

  • Influence of summer and winter climate variability on nitrogen wet deposition in Norway. Hole, L. R.; de Wit, H. A.; Aas, W. // Hydrology & Earth System Sciences;2008, Vol. 12 Issue 2, p405 

    Dominating wind patterns around Norway may change due to climate warming. This could affect transport of polluted air masses and precipitation. Here, we study relations between reactive nitrogen wet deposition and air mass transport during summer and winter expressed in the form of climate...

  • The 1997/98 Summer Rainfall Season in Southern Africa. Part II: Model Simulations and Coupled Model Forecasts. Lyon, Bradfield; Mason, Simon J. // Journal of Climate;Jul2009, Vol. 22 Issue 13, p3802 

    This is the second of a two-part investigation of rainfall in southern Africa during the strong El Niño of 1997/98. In Part I it was shown that widespread drought in southern Africa, typical of past El Niño events occurring between 1950 and 2000, generally failed to materialize during the...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics