Solar Radiation Management Primer
Geoeng Info
In 1991, Mount Pinatubo (Luzon, Phillippines) erupted in what was the second largest volcanic eruption of the 20th Century, sending 22 million tons of sulphur dioxide into the atmosphere. Sunlight reflected off that sulphur dioxide, and for the next several years, global temperatures were reduced by approximately half a degree Celsius.
The implications of that episode of planetary cooling may be significant, and scientists are studying whether sulphur dioxide ought to be intentionally released into the atmosphere at certain elevations and latitudes, and at certain times of year, in order to generate that same cooling effect again.1
SRMprimer.org aggregates foundational science involving Solar Radiation Management (SRM) and is designed to be a companion site to CDRprimer.org, which aggregates foundational science involving Carbon Dioxide Removal (CDR).2
It sounds like science fiction - a fleet of planes operating in the Arctic, distributing sulphur dioxide high above the poles to reflect sunlight.3 The fact that serious scientists are now researching it is unfortunately a testament to how dire our climate crisis has become.
There is no reason to think that either CDR or SRM has the potential to reverse damage caused by the climate crisis. Methane, once released, does not get recaptured into refrozen ice.4 And glaciers, once melted, would require another ice age to reform.5 At best, CDR and SRM only have the potential to slow further damage caused by the climate crisis.
This four-page 2021 paper on SRM in the Arctic is an excellent place to begin: Sustaining the Arctic in Order to Sustain the Global Climate System.6
Created with the generous involvement of the Cornell University Climate Geoengineering group, the SRM Primer itself may be found here.
1. Scientists are also researching whether it would be better to use something other than sulphur dioxide.
2. The team that built SRMprimer.org is unrelated to the team that built CDRprimer.org, which is highly recommended. The work of its leaders Jennifer Wilcox and Jeremy Freeman are also highly recommended. If CDR scales to capture tens of gigatons of CO2 per year, there will be far less need for anyone to ever consider SRM.
3. Approaches aside from SAI are also being researched. One of the more viable of those is Marine Cloud Brightening (MCB), by which seawater would be pumped into the air, forming temporary reflective clouds, similar to the exhaust trails left behind by ships at sea.
4. For data on thawing Arctic permafrost and other climate crisis metrics, see Woodwell Climate Research Center (www.woodwellclimate.org). The work of Sue Natali deserves special attention in this context, with an awareness that cooling the Arctic using SRM will never get already released methane back into the permafrost.
5. See the work of the International Cryosphere Climate Initiative, most notably their November 2021 report.
6. The spinning of the earth would drive any SAI release towards the poles. For this reason and others, the referenced paper focuses on the Arctic. However, research on regionality of SAI is nascent. The citation of this paper is: Bodansky, D.; Pomerance, R. Sustaining the Arctic in Order to Sustain the Global Climate System. Sustainability 2021 , 13, 10622. https://doi.org/10.3390/su131910622