Abstract
Abstract. Climate change and constant population growth pose severe challenges to 21st century rural Africa. Within the framework of the West African Science Service Center on Climate Change and Adapted Land Use (WASCAL), an ensemble of high-resolution regional climate change scenarios for the greater West African region is provided to support the development of effective adaptation and mitigation measures. This contribution presents the overall concept of the WASCAL regional climate simulations, as well as detailed information on the experimental design, and provides information on the format and dissemination of the available data. All data are made available to the public at the CERA long-term archive of the German Climate Computing Center (DKRZ) with a subset available at the PANGAEA Data Publisher for Earth & Environmental Science portal (https://doi.pangaea.de/10.1594/PANGAEA.880512). A brief assessment of the data are presented to provide guidance for future users. Regional climate projections are generated at high (12 km) and intermediate (60 km) resolution using the Weather Research and Forecasting Model (WRF). The simulations cover the validation period 1980–2010 and the two future periods 2020–2050 and 2070–2100. A brief comparison to observations and two climate change scenarios from the Coordinated Regional Downscaling Experiment (CORDEX) initiative is presented to provide guidance on the data set to future users and to assess their climate change signal. Under the RCP4.5 (Representative Concentration Pathway 4.5) scenario, the results suggest an increase in temperature by 1.5 ∘C at the coast of Guinea and by up to 3 ∘C in the northern Sahel by the end of the 21st century, in line with existing climate projections for the region. They also project an increase in precipitation by up to 300 mm per year along the coast of Guinea, by up to 150 mm per year in the Soudano region adjacent in the north and almost no change in precipitation in the Sahel. This stands in contrast to existing regional climate projections, which predict increasingly drier conditions. The high spatial and temporal resolution of the data, the extensive list of output variables, the large computational domain and the long time periods covered make this data set a unique resource for follow-up analyses and impact modelling studies over the greater West African region. The comprehensive documentation and standardisation of the data facilitate and encourage their use within and outside of the WASCAL community.
Highlights
With climate change being one of the most severe challenges to rural Africa in the 21st century, West Africa is facing an urgent need to develop effective adaptation and mitigation measures to protect its constantly growing population (Neumann et al, 2007; Naab et al, 2012; Eguavoen, 2013; Kirtman et al, 2013; Niang et al, 2014)
A novel set of high- and medium-resolution climate change simulations for the greater West African region is provided to the research community within the framework of WASCAL, which advances significantly beyond currently available data sets
The ensemble uses the Weather Research and Forecasting Model (WRF) to downscale three different global circulation models for three 30-year periods between 1980 and 2100, completed by a reanalysis-driven control run for the historical period 1980–2014
Summary
With climate change being one of the most severe challenges to rural Africa in the 21st century, West Africa is facing an urgent need to develop effective adaptation and mitigation measures to protect its constantly growing population (Neumann et al, 2007; Naab et al, 2012; Eguavoen, 2013; Kirtman et al, 2013; Niang et al, 2014). Advances in computational power and in exploiting parallelism in numerical codes nowadays allow us to run regional climate models (RCMs) at resolutions of 10 km until 2100 (Bruyère, 2013) These RCMs can add significant value to global reanalyses and GCMs and in particular lead to an improved representation of the West African monsoon (WAM; see Sylla et al, 2013, and references therein). First high-resolution RCM studies over West Africa were conducted by Jung and Kunstmann (2007) using the mesoscale meteorological model MM5 (Grell et al, 1994) at 9 km resolution for two time slices, 1991–2000 and 2030– 2039, over a comparably small region covering the Volta Basin They showed an annual mean temperature increase of around 1.3 ◦C in the Volta region, significantly exceeding the interannual variability, and a mean annual change in precipitation from −20 to +50 %.
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