A decade ago, I helped convene SRM Science 2015 in Cambridge to focus squarely on the science and engineering of solar radiation management. We brought ethics and governance into the room too, but the goal was clear: get serious about the mechanics of cooling a dangerously warming planet. Ten years on, I’m disappointed by how little the mainstream conversation has moved. The science has progressed; the politics and public understanding have not. This is no longer an academic curiosity. It’s a necessary line of defense because we have failed, collectively, to cut emissions fast enough.
Let’s be blunt. After 30 years of climate negotiations, we did not deliver the rapid fossil fuel decline needed to avert deep damage. A generation ago it was reasonable to call geoengineering a dangerous distraction. Today, refusing to research it is reckless. The UK government’s decision to fund research into cooling the planet is not a “win” for me; it’s a grim acknowledgment of where we are. We need every responsible option on the table.
Some argue that geoengineering—particularly Stratospheric Aerosol Injection (SAI)—should be outlawed. There’s even a Westminster debate driven by more than 160,000 signatories calling for a ban. Banning SAI and carbon removal together is like banning food because food sometimes carries disease. It removes essential tools at the moment we most need them. Carbon removal can lower atmospheric CO2, but not at the speed or cost scale required to cool the system in the next few years. By contrast, modest albedo enhancement—making clouds a bit brighter and the stratosphere slightly “milkier”—could reflect 2–4% more sunlight and begin bending the heating curve within a year or two at globally achievable cost. That speed is not a gimmick; it’s the point.
My focus is practical: reduce summer melt and enhance winter refreeze in the Arctic. In summer, SAI and other albedo techniques can lower absorbed solar radiation and slow sea-ice loss. In winter, when the sun vanishes, we can help the system dump heat to space. That means ice-thickening projects—pumping seawater onto sea ice to accelerate freezing—and thinning winter cloud cover that otherwise acts like a blanket. None of this is magic. It’s physics. The research task is to probe side effects with eyes wide open, ramp cautiously, and measure everything. I am convinced that the likely risks of well-governed, modest interventions are smaller than the fully intended consequences of business-as-usual warming.
What’s missing is policy literacy. Inside the inner sanctum of COP negotiations, SAI, marine cloud brightening, and Arctic cooling barely register. Carbon removal has crept into net-zero plans; SRM remains a political taboo. I speak on the fringes—panels, side events, discussions—but that isn’t policy traction. Too many policymakers still don’t know what geoengineering actually is, which makes fear narratives sound like prudence. In the meantime, thresholds keep arriving early and systems destabilize in real time.
Consent and justice must be built in from the start. Interventions proposed for the Arctic will rightly face scrutiny from Indigenous communities who bear the local risks. At the same time, small island states are confronting the slow erasure of their nations from sea-level rise and will understandably push for accelerated cooling. We need these voices in the same room, not siloed. At our Arctic Repair Conference in Cambridge at the end of June, we’re bringing Arctic Indigenous leaders and Pacific Island representatives together on a single panel—a conversation that should have happened years ago. The experience on the Great Barrier Reef, where Aboriginal communities have supported local marine cooling trials, shows that co-design and social license are possible when the objectives are clear and the benefits are tangible.
Let me be clear about priorities. Emissions cuts are non-negotiable. Carbon removal is essential. But neither will cool the climate on the timescale that matters to prevent cascading harms in the next decade. That is where SAI earns consideration: it is fast, comparatively affordable, and systemically consequential. Precisely because of that, it demands transparent governance, careful staging, and international oversight. The goal is not to flip a planetary dimmer switch overnight. It is to determine—through rigorous, publicly accountable research—whether modest, targeted interventions, especially in the Arctic, can reduce extremes, stabilize weather patterns, and buy time for the heavy lift of decarbonization and drawdown.
What do I want from the conference? A line in the sand. An end to the caricature that this work is the province of “nutcases trying to control the climate.” We are dealing with irreversible damage already done, and with a narrowing window to protect what remains. We have important messages for policymakers: stop treating SAI as unspeakable. Fund the science. Build the governance. Test carefully. Learn quickly. Adjust.
If Westminster chooses prohibition over preparation, it will not make risk disappear. It will simply remove one of the only levers that can act on the right timescale. The weather is not waiting. Neither should the research. We can’t be sidelined forever.
