Publication: Modelling the impact of SRM on West African monsoon precipitation

Guinea-Bissau, the Sahel, and the Sahara Desert from International Space Station. Credit: NASA Visible Earth

The 2018 Benin Degrees Modelling Funded (DMF) team has published a new paper modelling the impact of solar radiation modification (SRM) on monsoon precipitation in West Africa.

In Benin and West Africa in general, global warming is anticipated to cause major disruption to regional hydrology. On top of rising temperatures, climate change  is expected to lead to an increase in severe flooding, rising sea levels, and changes to monsoon precipitation patterns. These changes could have dramatic socio-economic consequences for Benin and the region more broadly as the monsoon “is the major source of water for agriculture in West Africa”. Changes in monsoon patterns would have knock-on impacts across agriculture, fisheries, water resources and human health in a region dependent on subsistence farming.

The team used climate simulations to model the possible impacts of SRM against climate change based impacts on a middle of the road climate scenario. They found that, under a scenario of moderate global warming, there were only very small changes in rainfall across West Africa and the Sahel. However, under SRM they found, relative to the world of climate change, a modest, ~4% reduction in rainfall in West Africa, but larger reductions of ~8.5% and ~17.5% in the South and North Sahel, respectively.

The study aligns with some previous studies which suggest that SRM could lead to a decrease in rainfall, particularly in monsoon regions, when used to fully offset global warming in certain climate change scenarios. However, it is important to note that there are large uncertainties in regional rainfall projections. The authors suggest that further research is needed into the impact of SRM on monsoon patterns to better understand why SRM leads to a decrease in precipitation in West Africa under these scenarios. 

Stratospheric Sulfate Aerosols Impacts on West African Monsoon Precipitation Using GeoMIP Models in Earth’s Future by Frédéric Bonou, Casimir Yelognisse Da-Allada, Ezinvi Baloitcha, Eric Alamou, Eliezer Iboukoun Biao, Josué Zandagba, Ezéchiel Obada, Yves Pomalegni, Peter James Irvine, and Simone Tilmes.