DMF paper: Exploring SRM’s impact on temperature and precipitation in South Africa

satellite image south africa
South Africa, Cape Town taken during a day pass by the Expedition 40 crew aboard the International Space Station (ISS), 2014. Photo Credit: NASA

The 2018 South African Degrees Modelling Fund (DMF) team led by Dr Chris Lennard at the University of Cape Town has published the research from their student Trisha Patel’s master’s dissertation (read about Trisha’s achievement here). The paper compares the impacts of solar radiation modification (SRM) and climate change on temperature and precipitation over South Africa by modelling future scenarios to the end of the 21st century.

Method and results

The team investigated several SRM scenarios that offset future global warming by injecting sulphur dioxide at different altitudes and latitudes. They compared these scenarios against an extreme scenario of future greenhouse gas emissions where, rather than falling, emissions continue accelerating into the future, leading to intense global warming.

The paper found that, in the scenario studied, SRM could effectively counter the rise in temperatures projected to happen due to climate change, having “positive implications for water resources (through reduced evaporation), human health, agriculture, urban centres, and vulnerable communities”.  It also found that SRM could reduce extreme precipitation events in summer across some areas but simultaneously increase the likelihood of these events during winter in other areas. Their results suggest that SRM, when used to counter a very high level of warming, could have an uneven impact on precipitation at a national scale.

Further research

The researchers highlighted the limitations of the SRM scenarios that they used, which could be better tailored to offset climate change over South Africa. For instance, they recommended that further research compare SRM against “middle of the road” future global warming scenarios, rather than the extreme scenario used in this study. Similarly, they also encouraged future studies to explore the effect of using different injection locations (for example, in the Arctic or the Southern Hemisphere) to better understand how this could affect the results.

Potential impact of stratospheric aerosol geoengineering on projected temperature and precipitation extremes in South Africa  in Environmental Research: Climate by Trisha Patel, Romaric C. Odoulami,  Izidine Pinto, Temitope S. Egbebiyi, Christopher Lennard, Babatunde J. Abiodun and Mark New.