Main methods that are considered within solar radiation management are stratospheric aerosol injection (SAI), which creates a protective aerosol “parasol”, and marine cloud brightening (MCB), which increases cloud reflectivity over oceans. While these methods could slow warming, their effectiveness and side-effects, such as ozone depletion and altered weather patterns, are uncertain.
The team behind the QUESTION project will use novel data-science approaches and factor into their models the challenges in mimicking SRM effects, separating SRM signals from other factors, as well as ongoing improvements to climate models. This research will help assess SRM's risks and benefits and the team hope that it will support informed climate action.
Dr Ying Chen, Assistant Professor in Atmospheric Science at the University of Birmingham and the principal investigator on the QUESTION project said:
“Solar radiation management has the potential to be a last resort to slow down man-made climate change buying more time for Net-Zero, but the potential detrimental impacts, such as ozone depletion and extreme precipitation, are currently unknown.
“The QUESTION project will look to real-world natural analogues, that have happened in the recent history and therefore no worrying of side-effects from any new field experiences, and will give us clues what might happen should we attempt to do solar radiation management. so that we can better understand what potential implications there might be. After all, there’s no planet B yet in our current universal horizon.“
Computer modelling and machine-learning studies
The QUESTION project is one of four research projects which explore the feasibility of some unconventional measures to mitigate global temperature rises.
Using computer modelling and data-driven research only, the five-year studies will investigate the impact of:
Stratospheric aerosol intervention – the process of adding particles into the atmosphere that will reflect the Sun’s rays.
Marine cloud brightening – this technique aims to increase the reflectivity of clouds over the ocean by spraying sea water to create more cloud condensation nuclei.
How the environment might respond to SRM by comparing to real world natural analogues such as volcanic eruptions and changes in ship emissions.
The cooling potential of four less well known SRM approaches, three focused on solar or terrestrial radiation and one examining the use of tiny, rod-like nanoparticles (cellulose nanocrystals) derived from natural cellulose sources to enhance the effectiveness of stratospheric aerosol intervention.
Professor Louise Heathwaite, Executive Chair of the Natural Environment Research Council, said:
“NERC invests in a wide range of research to tackle, adapt to, and mitigate climate change. The UK’s priority is to tackle the root cause of climate change by reducing emissions of greenhouse gases from human activities and adapting to those impacts that are unavoidable.
“However, with the increased interest in deploying solar radiation management measures, there is a pressing need to consider the impact of SRM approaches to control Earth system temperature. These research projects will analyse these approaches in detail and address ethical and governance considerations.”
The studies are part of NERC’s Modelling environmental responses to solar radiation management programme.