UNEP Report on SRM Draws Mixed Reactions From Experts

In the Global South, scientific inquiry on SRM is nowhere near a settled issue. It warrants further engagement. So UNEP’s recent working paper on SRM is an important contribution to a necessary global conversation. While the title “…scientific evidence does not support SRM as a viable climate solution” may be contextually implied for deployment pathways, it can also unintentionally create the impression that SRM no longer warrants further inquiry or scientific engagement. This can be misleading, yet the content of the paper itself is far more nuanced and forward-looking.

Every engagement around SRM should be guided by robust scientific evidence. Importantly, SRM research is not simply about implementation. Research exists to strengthen scientific understanding, assess uncertainties, improve governance preparedness and support informed decision-making.

I agree with UNEP on several critical points: SRM is not a substitute for emissions reductions and adaptation, governance gaps remain significant, and the environmental, ethical and geopolitical risks are profound. These concerns are true and constructive and consistently emerge across stakeholder and public engagements, which is precisely why transparent and inclusive dialogue is so important.

The real challenge before us is how to govern inquiry responsibly. Research governance is key. Without transparent governance, accountability, and equitable participation, discussions risk being shaped by a narrow set of actors and interests. Without research and open dialogue, vulnerable regions like Africa may be forced into future decisions without adequate knowledge, representation, or preparedness.

Precaution should therefore not mean silence, but inclusive, transparent, and critically governed engagement.

Read Portia’s full comment on LinkedIn.

Everyone should welcome this working paper. It calls research a prerequisite for informed risk assessment, warns against prohibiting inquiry, lays out the most specific governance blueprint UNEP has ever produced, and centers precaution and equity throughout. Within the constraints UNEP navigates, from divergent member states to civil society that can’t agree on whether the conversation should even happen, this paper advances productive proposals for research governance while walking a tightrope. Read the whole thing.

The question is the title. The body doesn’t support that framing, so where does it come from? Political necessity, with certain member states or civil society blocs rejecting the paper without it? Institutional positioning, with UNEP protecting itself from the charge of legitimizing SRM? Or simply that a working paper calling for governed research doesn’t survive internal review without first establishing that deployment is off the table? I have no idea. But whatever the reason, the implication is instructive.

Aside from that, bravo UNEP.

Some observers have suggested that the paper is biased against SRM, pointing specifically to its subtitle (“Scientific evidence does not support SRM as a viable climate solution”) and text on the first page/front cover. Statements like the following support this reading: “The current state of scientific knowledge does not support SRM as a viable response to climate change as it does not address the root cause of the current anthropogenic climate change.” If viability hinges on directly addressing emissions, then how does UNEP justify its support for adaptation, which features throughout the paper? One gets the sense that the authors – or at least those responsible for writing the first page – just don’t like SRM, which is a fine opinion but not a finding based on scientific evidence.

Other elements of the paper are more heartening, however, including the way it characterizes support for a Non-Use Agreement. Specifically, after noting that “Some wish to silence discourse,” the paper shortly thereafter observes that “some advocates of restrictive governance frameworks argue that even discussing – or researching – solar geoengineering risks legitimizing it and diverting attention from the urgent need to decarbonize global socio-economic systems, and thus open debate on SRM is often framed as counterproductive to effective climate action (Gupta et al. 2020; EnviroNews 2024; Oomen 2025).” In recognizing that at least some supporters of the Non-Use Agreement not only oppose SRM but are actively trying to suppress research and debate, UNEP shows a refreshing willingness to pull no punches.

UNEP’s new working paper on Solar Radiation Modification cites my Nature Climate Change paper five times. The citations are accurate, and I welcome a UN agency engaging seriously with African scientific voices on this debate.

One phrase in the subtitle warrants scrutiny:

“Scientific evidence does not support SRM as a viable climate solution.”

This sentence conflates two distinct scientific positions, and the distinction matters for how Africa engages with the SRM debate.

Position A: The evidence is insufficient to justify deployment.

Position B: The evidence does not support viability.

These are not the same claim, and the major scientific assessments do not support Position B.

If the public takeaway is “science says SRM does not work,” African research capacity loses its case for funding. African scientists get sidelined from a debate that continues regardless in the Global North. Decisions that affect African rainfall, agriculture, and water systems risk being made without African scientific leadership.

My paper, which UNEP cites, argues for the opposite trajectory. Africa must move from passive recipient to active leader in SRM research, governance, and public engagement. That argument depends on the scientific question remaining open.

To be clear, SRM is no substitute for mitigation. UNEP itself explicitly notes the broad scientific consensus that mitigation and adaptation remain far more reliable and urgent. Mitigation is the priority. SRM cannot replace it.

But studying a possibility is not endorsing its deployment. The difference between insufficient evidence and disqualifying evidence is the difference between an open scientific question and a closed one.

For Africa, the open one is the one we need.

Read Kwesi’s full comment on LinkedIn.

UNEP’s recent SRM report is a welcome contribution to an important debate. But its subtitle – “Scientific evidence does not support SRM as a viable climate solution”, and the key message in it repeated on the first page, and in the summary – are problematic in at least three ways.

First, nobody promotes SRM as a climate solution. Only emissions reductions and carbon removal are solutions; SRM, at best, could supplement these – and adaptation efforts – to limit temperature rises while the world decarbonizes.

Second, viability is a policy and governance judgment, not purely a scientific one. Conflating “not yet scientifically established” with “not viable” muddies a distinction that matters enormously for how governments and the public understand these technologies.

Third, and perhaps most importantly, the subtitle misrepresents what the report actually says. Read past the first page, and the content calls for substantially more research – especially in the Global South – greater international cooperation, broader assessments that also include ethics and justice, and urgent, inclusive governance frameworks to prepare for evidence-based decision-making on whether or not to deploy SRM. These are important messages. They deserved to be front and centre, not buried beneath a misleading headline.