Better knowledge of black carbon and climate change can save lives
A CICERO-led research project is expected to improve climate mitigation and adaptation in Sub-Saharan Africa and Asia. The key is to understand the role of black carbon in extreme precipitation changes.
In November and December 2025, more than 2,7 million people were affected by storms and flooding in Sri Lanka, Indonesia and Malaysia, according to World Weather Attribution. Only weeks before, Hurricane Melissa struck Jamaica and Cuba. Intensified by climate change, the hurricane brought torrential rainfall and life-threatening storm surges to coastal areas including the Dominican Republic and Haiti. And in October, Mexico was hit by very heavy rainfall which caused widespread flooding, overflowing rivers, and numerous landslides.
As global warming continues, such highly damaging extreme events are expected to increase in both number and intensity. However, what drives these changes differs from region to region, and the full picture is often much more complex than what is brought about by greenhouse gases alone.
– Recent science has highlighted black carbon as a significant and underappreciated driver of changes in mean and extreme precipitation in many populated regions, senior researcher at CICERO, Camilla Weum Stjern, explained.
More incidents of extreme rainfall may be expected in the near future, with devastating impacts on people and livelihoods. To understand why this happens, and where, is crucial for saving lives. The research project BlackRain sets out to bring new knowledge about how human activities and black carbon impact on rainfall changes and will deliver updated regional climate risk information. Specifically, the project aims to understand how black carbon affects rainfall patterns in South and Southeast Asia, and Sub-Saharan Africa.
The scientific findings are expected to contribute to better informed policy decisions on matters like air quality and industrialization, and improved mitigation and adaptation planning and preparedness for climate risk.
Stjern is project leader of the BlackRain project which is funded by Clean Air Fund. The project includes researchers from CICERO and University of Reading.
– Through policy and technological advances, important changes in black carbon emissions are expected over the coming decades that may lead to strong trends in rainfall which are not captured by current climate models, said senior researcher Bjørn H. Samset at CICERO, who is also involved in BlackRain.
The main physical process that causes black carbon to be a significant driver of change is atmospheric absorption: As the dark black carbon particles absorb short-wave radiation, this alters the atmosphere’s temperature profile and increases heat and moisture transport from the surface. Typically, these thermodynamic impacts stabilize the atmosphere and suppress cloud and precipitation formation, causing local drying. The warming from black carbon also triggers dynamic responses, that can modulate precipitation responses locally and remotely through changes in atmospheric circulation patterns. In addition, BC may act as ice or cloud condensation nuclei and impact cloud and precipitation formation at a microphysical level.
The BlackRain project was launched in 2025 and will continue until the end of 2027.