Geoengineering through solar radiation modification - a last chance option?

There is no doubt that we have the means and the knowledge to rapidly decarbonise, reach net zero, and become net negative. But success is not guaranteed. 

If we falter over the coming years, could geoengineering through solar radiation modification be a last chance option? Might we reach the point where we need to cool the planet, to give us a bit more breathing space while we decarbonise? Is it possible, or is it too dangerous? Would it undermine efforts to rapidly decarbonise? Would the benefits outweigh the risks, taking into account the harm already being done due to global heating?

How would the world decide whether to deploy solar radiation modification (SRM), or even whether to conduct research? Who would make these decisions and what would the guardrails be?

These questions are terrifying to contemplate. But so is the prospect of temperature rise beyond 1.5 degrees. 

Not surprisingly, there are deep divisions among the scientific community. Some scientists - including high-profile climate scientist James Hansen - consider our current situation is so dire that there should be a rigorous, rapid scientific assessment of the feasibility and impacts of SRM approaches.

There are other scientists who are resolutely opposed to SRM, and consider it a dangerous distraction from a focus on decarbonisation and greenhouse gas drawdown. 

In this episode, I talk to Janos Pasztor who for seven years worked with the Carnegie Climate Governance Initiative, which took neither a pro- or anti- approach to SRM, instead focusing on governance issues around solar radiation management. 

He also talks about a new report on SRM issued by the EU Commission's top scientific advisory body. 

Janos's previous roles include UN Assistant Secretary General for Climate Change and senior advisor on climate change to then UN Secretary-General Ban Ki-Moon, in the lead-up to the 2015 Paris climate COP that led to the Paris Agreement.

He has also held senior executive roles with environment group WWF International, the UN Environment Programme (known as UNEP), and with the secretariat to the UN Framework Convention on Climate Change.

Discover more on the various views on SRM:

• The Carnegie Climate Governance Initiative (operating from 2016 to 2023) https://c2g2.net
• Solar radiation modification - a report published in December 2024, by the EU Commission's Group of Chief Scientific Advisors. https://scientificadvice.eu/advice/solar-radiation-modification/
• SAPEA evidence review report - solar radiation modification, also published in December 2024 https://portal-cdn.scnat.ch/asset/3af0316d-c0f2-5ca6-b543-c9bdba33baa5/srmerr.pdf
• 'Impact of solar geoengineering on temperature-attributable mortality', also published in December 2024, https://www.pnas.org/doi/abs/10.1073/pnas.2401801121?af=R
• 'Safeguarding the polar regions from dangerous geoengineering' (November 2024) https://www.researchgate.net/publication/385550908_Safeguarding_the_polar_regions_from_dangerous_geoengineering
• 'An open letter regarding research on reflecting sunlight to reduce the risks of climate change,' (February 2023), signed by more than 100 physical and biological scientists studying climate and climate impacts, including James Hansen https://climate-intervention-research-letter.org