Black Rain

Precipitation changes are among the most impactful aspects of climate change. The links between human activities and rainfall changes are, however, not fully known. Absorption of sunlight by dark particles such as BC has recently been found to strongly affect precipitation, both locally, through thermodynamic processes, and remotely, through dynamical circulation change. However, the details of these connections are very poorly known, especially on a regional level, and therefore represent a key question for current atmospheric climate science. This means that when BC emissions change over the coming decades, through air quality policy, industrialization, or other factors, many highly populated regions may face strong trends in rainfall that are not captured by current climate models. BlackRain addresses this critical knowledge gap, by quantifying the role of black carbon emissions in near-term precipitation change and delivering updated regional climate risk information. 

BlackRain builds on recent advances in modelling, observations, scenario development, and physical process understanding. The project will have a particular focus on two regions in particular: 

i) South and Southeast Asia, where emissions of BC have been changing rapidly in the past decades, and future trends are potentially strong. The South Asian monsoon has previously been found to be sensitive to the presence of BC, in both observation- and model-based studies, making this area critical to study in more detail. 

ii) Sub-Saharan Africa, which is extremely vulnerable to changes in precipitation. Future emission trends in the region are thought to be very uncertain. This, as well as the fact that absorbing aerosols have been shown to cause precipitation increases in this region (contrary to the typical decrease), marks Sub-Saharan Africa as a region of interest for future BC-precipitation effects. 

The ambition of BlackRain is to contribute to better knowledge about precipitation change in general, and pin down the role of BC in both historical and future rainfall changes. We will produce and analyze novel model simulations to close knowledge gaps, use current knowledge to quantify the precipitation consequences of a broad set of emission scenarios, and translate the resulting climate risk information to regional stakeholders.