Morning traffic jam in Berlin, Germany 2023. Photo: IMAGO/Frank Sorge via Reuters Connect

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The UN confirmed that overshoot of 1.5°C is inevitable. But its response – focused entirely on emissions cuts and carbon removal – leaves SRM conspicuously off the table. That doesn't mean the conversation is at a standstill. Reflective's new research roadmap offers a concrete vision of the investment and time needed to reach an informed decision about stratospheric aerosol injection (SAI) deployment. At the same time, researchers, non-profit leaders, and Elon Musk have leaned into the overshoot announcement to re-examine the future of solar geoengineering. 

A research roadmap for SAI

Reflective has launched an interactive roadmap outlining research and funding priorities for SAI. It estimates that an informed decision about whether to begin deployment could be possible within 10 years, with $370 million in coordinated research funding. We asked experts to comment. Read their reactions. 

Overshoot comes into focus – and jumpstarts the SRM conversation 

The UN Environment Programme (UNEP) has issued a stark declaration: exceeding 1.5°C of warming is now inevitable, likely within the next few years. Its new report, "Limiting Overshoot", stresses that rapid emissions reductions remain the first priority and examines strategies for bringing temperatures back down – with a primary focus on carbon dioxide removal. But the report is also notable for what it leaves out: SRM goes unmentioned, consistent with UNEP's May paper, which concluded that scientific evidence "does not support SRM as a viable climate solution".  

We covered the overshoot report in depth in a recent edition of Reflections, our weekly LinkedIn newsletter. 

A new set of climate scenarios published the same month reinforce the picture. They project warming of 1.6°C to 3.3°C by 2100, with a "current policies" pathway reaching 2.9°C. Even the most optimistic scenarios now assume some overshoot of 1.5°C and heavy reliance on carbon dioxide removal. A study from Abernethy et al. suggests climate feedbacks could push warming higher still. Spark Climate Solutions drew on this research to produce an accessible explainer.  

Against this backdrop, the SRM conversation seems to be heating up 

An article in The Conversation argues that the taboo around SRM appears to be lifting as the world heads towards exceeding 1.5°C. The authors call for responsible research and public deliberation, arguing that Australia and other governments should prepare for the potential climate, geopolitical, and security implications.  

Also in The Conversation, Ben Redmond Roche draws on his recent academic paper to lay out what outdoor SRM experiments could realistically look like – from tiny balloon releases to larger aircraft-based tests – and what each could tell us. He argues that even the largest proposed experiments remain orders of magnitude smaller than deployment, and that the debate around them involves competing values that evidence alone cannot settle.  

Speaking with James Temple, Andy Parker and Aarti Gupta both rejected the idea that solar geoengineering is "becoming inevitable" – though from different positions. Gupta warned of unknowable risks and cited calls from the Global South for non-use; Parker argued it remains the only known way to rapidly cool the planet and that building research capacity in vulnerable countries would give them greater agency in the debate.  

Elon Musk re-entered the SRM conversation, claiming on X that "space satellites to control temperature and massive geo-engineering will be needed" to prevent "severe extinction events", arguing that switching to renewable energy is insufficient. The claim was made without supporting evidence. 

In a sign of SRM's growing visibility, The Daily Show addressed the topic through a comedy-laced segment featuring Luke Iseman, Shuchi Talati, and David Keith. 

Commuters in Kolkata cover their heads in the severe heat. Photo: Suprabhat Dutta

South Asia steps up on SRM research and governance 

The India Climate Cooling Summit in New Delhi brought together policymakers, scientists, and experts to discuss managing India's near-term climate risks. A special SRM-focused edition of Mahabahu Mirror, released alongside the summit, examined why India should advance research on sunlight reflection methods and how such research could be governed inclusively and responsibly. 

COMSATS University Islamabad hosted a workshop bringing together Pakistani policymakers, scientists, and international partners to present Pakistan-based research on SRM governance and its effects on drought, malaria transmission, and more. Officials emphasised the need for countries in the Global South to build their own evidence base and participate directly in international SRM discussions. 

New research and developments 

A paper by Visioni et al. describes a new set of standardised SRM scenarios for computer modelling studies. Part of the Geoengineering Model Intercomparison Project, the scenarios range from more technical, idealised simulations to more exploratory scenarios covering potential interactions with temperature overshoot and tipping points. 

In their study, Lee et al. explore how conservatism and climate denialism influence support for SRM using 2022 survey data from countries in North America and Western Europe. They find that conservatives tend to be less supportive of SRM, but that this is mainly true among those with climate denialist beliefs, and climate deniers tend to be politically conservative. 

A paper by Schmale et al. discusses Arctic geoengineering, covering scientific perspectives on various approaches, governance and ethical concerns, and potential paths forward for research. The authors conclude by highlighting the importance of justice, scientific rigour, and inclusive decision-making. 

Andrew Lockley shared some details of two high-altitude drones he is seeking to certify, noting potential defence and SAI applications – one capable of lifting roughly 40 kg to 13 km, the other roughly 500 kg to 20 km, far above most aircrafts' ceiling. Many details are lacking due to "defence industry restrictions", though he has been developing drones with an unnamed manufacturer for years and has presented earlier work at conferences. 

The Observer reports that newly released, heavily redacted UK government documents show the Ministry of Defence's research arm contracted "deep tech" firm Cambridge Consultants last year to research solar geoengineering. The article reports that the release demonstrates for the first time that the UK security services have funded research in the field. 

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