It sounds like sci-fi until you read the footnotes. “Dimming the sun” – the blunt nickname for solar geoengineering – has leapt from academic journals to breakfast-TV conversation and policy memos.
The basic pitch is simple: make Earth a little shinier so it reflects more sunlight back to space, cooling the planet quickly. The reality, as reporters and researchers keep stressing, is anything but simple.
Chloe Baul, writing for Courthouse News Service, covered a new Columbia University study that throws a bucket of cold water on the idea that we can fine-tune the climate like a thermostat.
On CTV’s Your Morning, anchor Anne-Marie Mediwake pressed American University’s Simon Nicholson on what “dimming the sun” really involves, who would be affected, and whether it’s even wise to try.
Their answers align on one core point: if this ever happens, it won’t be tidy.
The Idea In Plain English
Nicholson told Mediwake there are a few main ways scientists think we could reflect more sunlight. One is marine cloud brightening – spraying tiny droplets of ocean salt into low-lying clouds so they become whiter and bounce more light back into space.
Another is stratospheric aerosol injection (SAI) – flying high-altitude aircraft to release reflective particles, often sulfur compounds, into the stratosphere. Both would, in different ways, make parts of the Earth–atmosphere system a bit more mirror-like.
This isn’t pulling a concept out of thin air. When Mount Pinatubo erupted in 1991, the sulfate aerosols it lofted into the stratosphere cooled the planet by nearly a degree Celsius for a short time.
That natural experiment has tempted some to ask: if volcanoes can cool the climate, could we, in a controlled way, do the same?
Baul’s reporting on the Columbia team’s new paper makes clear that the “controlled way” is the snag.
Why Stratospheric Aerosols Are So Messy
Atmospheric chemist V. Faye McNeill and colleagues argue we’ve been lulled by idealized models. In simulations, the particles are perfectly sized and perfectly dispersed.
In the real world, the Columbia team says, almost nothing is perfect – not the materials, not the timing, not the geography, and certainly not the politics.
Where and when you inject aerosols matters enormously. Release near the poles, and you could nudge tropical monsoons. Target the equator, and you might tug on the jet stream or shift rainfall belts.
The Columbia group’s bottom line, as Baul put it, is that “dimming the sun” is not as simple as loading a few planes with sulfur and letting them rip. Even small missteps could reverberate across continents, not just counties.
There’s also the chemistry. Sulfate aerosols, the workhorse of model studies, risk thinning the ozone layer and contributing to acid rain. Alternatives like calcium carbonate, alumina, or titanium dioxide have been proposed to avoid some of those harms.
But as lead author Miranda Hack noted in the Columbia release, many of these materials are scarce, expensive, or devilishly hard to disperse in the ultra-fine sizes needed to remain aloft. In practice, particles clump. Clumps scatter light differently. Cooling becomes less predictable — and potentially less effective.
My take: if the particles you can actually buy, ship, grind, and loft don’t behave like the particles you idealize on a supercomputer, your risk envelope balloons. That doesn’t make SAI impossible. It makes it a lot less controllable than its simplest elevator pitch suggests.
“Reversible” Doesn’t Mean Risk-Free
Mediwake pressed Nicholson on a key public-safety question: if we tried something like this and didn’t like the results, could we stop?
Marine cloud brightening is, in principle, quick to switch off. Salt droplets wash out in days to weeks. Stratospheric aerosols linger far longer – roughly a year to 18 months for many candidates.
In that sense, yes, you can change your mind. But there’s a catch Nicholson emphasized: if you begin a program that offsets some of the warming from greenhouse gases, you’ve created a dependency. Stopping abruptly would reveal the “masked” warming very quickly, a snapback known as termination shock.
The hotter baseline you’ve been hiding reappears – potentially with a vengeance.
That forces a political truth we shouldn’t dance around: any serious SAI program is not a weekend pilot. It’s a commitment measured in decades.
Global Impacts, Global Politics
Nicholson was blunt about jurisdiction. Marine cloud brightening might skew regional weather, but stratospheric aerosols are global by design.
Clouds don’t carry passports; stratospheric winds are nobody’s private property. That means any deployment would affect countries that didn’t vote for it, potentially creating winners (cooler summers) and losers (shifted rains).
Baul’s reporting underscored that, beyond chemistry and physics, geopolitics could be the true Achilles’ heel.
Columbia climate economist Gernot Wagner argued that most modeling papers assume away the human complications – uneven interests, resource bottlenecks, fragmented governance. In his words, it “isn’t going to happen the way that 99 percent of these papers model.”
If a handful of governments or even a single wealthy nation decided to go it alone, we could be staring at the world’s first truly planetary transboundary dispute. Who arbitrates harms? Who pays for unintended droughts? Who gets to turn the dial up or down?
My view: the longer we punt on building even the most basic international rules of the road, the higher the odds that some actor tests the envelope unilaterally. That’s the nightmare version of “innovation.”
The National Academies’ Nudge: Study First
One reason this conversation is heating up is the push to fund more research. Mediwake noted that the National Academies of Sciences has recommended on the order of $100–$200 million to study solar radiation modification.
Nicholson framed this correctly: these are defensive technologies – last-resort options in case the world fails to cut emissions fast enough. Research is not deployment. It’s a way to understand risks, design small-scale, ethical experiments, and – critically – learn when not to proceed.
There’s an uncomfortable honesty in Nicholson’s framing: if we’re even talking seriously about “dimming the sun,” it’s because we are failing at the primary job – stopping greenhouse gas pollution.
Solar geoengineering doesn’t solve climate change. It papers over the fever while the infection rages.
My editorial two cents: fund the research. And do it transparently, with international partners, citizen oversight, and clear off-ramps. Better to know what not to do than to fly blind into a moral hazard.
Engineering Reality Check: Logistics, Materials, Money
Baul’s piece laid out the brick-and-mortar blockers that rarely make headlines. Sourcing millions of tons of the “right” mineral every year.
Grinding it to the sub-micron range without blowing up costs. Building aircraft or balloons that can reliably deliver to the stratosphere at scale. Avoiding particle clumping in dry, turbulent air. Then repeating the whole operation year after year, because aerosols fall out.
Hack’s warning was pointed: “A lot of the materials that have been proposed are not particularly abundant.”
Even the best-in-class candidate, calcium carbonate, presents engineering headaches. Bigger aggregates scatter light in the wrong way, dulling the effect we’re paying for – and introducing new uncertainties we don’t yet understand.
This is where “it works on paper” crashes into “call procurement.”
Both the Columbia team and Nicholson converge on a pragmatic stance. Solar geoengineering might reduce some climate risks – deadly heatwaves, rapid ice loss, storm intensity – if done carefully.
But it creates other risks – altered precipitation, ozone damage (for sulfates), geopolitical flashpoints, and the aforementioned termination shock. No choice is risk-free. The only guaranteed win is slashing emissions and removing carbon at historic scale, because that addresses the root cause rather than its symptoms.
Baul quoted McNeill’s warning that the range of possible outcomes is much wider than most people appreciate. That’s a scientist’s way of saying: humility, please.
So, Should We Dim The Sun?
Not now. Maybe never. But we do need to know – not assume – what these tools can and cannot do.
Chloe Baul’s reporting makes the Columbia case: models have oversold controllability; materials and logistics are nontrivial; global coordination is indispensable and unlikely.
Anne-Marie Mediwake’s thoughtful questions drew out Simon Nicholson’s core cautions: the effects won’t respect borders, “reversible” carries hidden risks, and contemplating these options is an admission that we’re behind on emissions.
My bottom line: accelerate emissions cuts like our lives depend on it (they do), scale carbon removal responsibly, harden societies against climate shocks, and build an international research framework that studies solar geoengineering in the open.
If we ever decide to touch the global dimmer, it should be with eyes wide open, global consent, and a finger hovering over the off switch – not because we were seduced by a tidy graph, but because we soberly judged the alternative to be worse.
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Growing up in the Pacific Northwest, John developed a love for the great outdoors early on. With years of experience as a wilderness guide, he’s navigated rugged terrains and unpredictable weather patterns. John is also an avid hunter and fisherman who believes in sustainable living. His focus on practical survival skills, from building shelters to purifying water, reflects his passion for preparedness. When he’s not out in the wild, you can find him sharing his knowledge through writing, hoping to inspire others to embrace self-reliance.
