Webinar Question by participant: NAS Report Governance and Social Aspects: Presenting the topic to the public

Simone Tilmes

Staff member
(1) With respect to terminology in presenting the topic to the public, why was the word “impacts,” with its generally negative connotation, chosen as the overview word for expressing the potential net outcome of SRM? The intent of any type of intervention, at least, is for the benefits to far exceed the adverse consequences. When describing developments of medical drugs, the focus is really mainly on the benefits, but then also the limitations, etc. rather than seeming to play down the large potential benefits and talk mostly about the problems as done in describing SRM.
(2) This gets to the related question of also providing the appropriate context for the public in the use of the word “uncertainties” about SRM. In saying uncertainties are large, what is the comparison to? It seems to me that the comparisons for both evaluating potential outcomes and for expressing uncertainties should be with respect to our understanding of what lies ahead given the various scenarios for extent of mitigation and adaptation. For high emission scenarios, uncertainties about SRM are likely small compared to risks of climate change without SRM whereas for very low emission scenarios the uncertainties are likely large in terms of outcomes, although there are very large uncertainties about the world actually being able to quickly get to low emissions. It just seems to me that there is missing context in the communication of the situation in this field.


Lisa Dilling
New member
The report describes the questions about efficacy as understanding how addition of materials affects reflection and transmission of atmospheric radiation, and as assessing climate response (affecting key climate outcomes). The term other impacts is used for impacts beyond those key climate outcomes. Uncertainties was used, as mentioned in the webinar, to convey the point that research programs do not always reduce uncertainties, and sometimes expand them. Agree that there are large uncertainties also in the extent of mitigation and adaptation as mentioned in this comment. The NASEM report discusses the decision context for SG and recommends considering SG in the context of the full portfolio of climate response strategies including mitigation and adaptation.