Break Glass, Cool Planet
Why We Need to Buy Time Through Global Cooling
Here's the unvarnished truth: We need to buy more time for carbon removal to scale, and that means we need global cooling interventions – soon. Not as a replacement for carbon removal, but as a bridge to give carbon solutions the runway they need.
James Hansen put out a paper in February that scared the crap out of me. If you want to know what shook me out of my sabbatical from carbon removal and climate stuff post-Nori, it was this paper:
In it, Hansen and team show that we’ve already breached the 1.5 °C threshold—around a decade sooner than mainstream projections—and they argue that holding warming below 2 °C is now implausible without additional cooling measures. The climate emergency isn’t on the horizon; it’s here and accelerating. If the world fails to curb forcing over the next decade, we run a serious risk of crossing irreversible tipping points such as west Antarctic ice sheet collapse while large-scale carbon removal solutions are still ramping up.
So what does that acceleration mean? We need to start preparing NOW for cooling interventions that could deploy within a decade. And that preparation is exponentially more complex than what we faced with carbon removal.
Why Emissions Cuts and Carbon Removal Still Aren’t Enough on Their Own
The Rocky Mountain Institute says we must be pulling 285 million tonnes of CO₂ out of the sky every year by 2030 to stay on a glidepath to 10 billion tonnes by 2050. Today we’re delivering only hundreds of thousands—a rounding error against that target.
Even if we crank the carbon removal flywheel to full speed, hitting 10 Gt in a quarter-century demands a level of coordination, capital, and sustained political will that makes the wartime industrial mobilizations look quaint. And remember: this Herculean lift rides on top of the non-negotiable job of driving emissions to (effectively) zero. Every tonne we keep out of the atmosphere in the first place is one we don’t have to claw back later—so yes, radical decarbonization remains the front line of defense.
But perfect execution takes time. Markets need to be redesigned, projects need to be built, supply chains need to mature. Decades will pass before carbon removal scales to its full potential, even with emissions dropping as fast as humanly possible. Climate tipping points, unfortunately, operate on their own clock.
That’s why I am now banging the drum for global cooling interventions—not instead of cutting and removing carbon, but as a prudential hedge while we sprint to scale. Think of it as buying an insurance policy that protects coral reefs, permafrost, and ice sheets—the very systems that both regulate climate and underpin many nature-based removal strategies—while we overhaul the energy system and grow the carbon removal industry to gigatonne speed. We’re in a dead-heat: solutions versus tipping points. To win, we’ll need all three lanes open at once—reduce, remove, and cool.
The Tipping Points We Can't Afford to Cross
The problem with climate tipping points is that we don’t actually know when we’re going to hit them. And like any tipping point in any system, at first they will seem far away, and then suddenly they will go—all at once. Because we can’t pinpoint those thresholds in advance, the only safe strategy is to stop warming well before we reach them. There is little margin for error. Here are some of the worst tipping points that we face in this century:
Ice Sheets: The Thwaites Glacier situation in western Antarctica is far worse than most people realize. Once warm water infiltrates under the ice shelf, the grounding line retreats down a backward-sloping bed, creating a potentially unstoppable feedback loop. We're talking potential meters of sea level rise that would reshape coastal cities worldwide. (And Thwaites is not the only ice sheet to be concerned about.)
Atlantic Meridional Overturning Circulation (AMOC): AMOC is the Atlantic Ocean’s great conveyor belt, ferrying warm, salty surface water north and returning cold, dense water south at depth. A slowdown would cool Europe, shove the tropical rain belt southward, spike sea level on the US east coast, and tangle jet-stream patterns that steer storms.
Coral Reefs: When water temperatures exceed thermal tolerance thresholds for just a few weeks, mass bleaching occurs. The Great Barrier Reef has already experienced multiple severe bleaching events. These aren't just pretty tourist attractions – they're the nurseries of the ocean and critical to food security for hundreds of millions of people.
Arctic Systems: As permafrost thaws, it releases not just CO₂ but methane – a greenhouse gas 86 times more potent over a 20-year period. This creates a feedback loop that accelerates warming far beyond what our current models predict.
The Carbon Removal Catch-22: Here's something that doesn't get enough attention – warming itself threatens our carbon drawdown tools. As regions experience shifting weather patterns, droughts, and temperature increases, the very land-based solutions we're counting on – like forests and agricultural soil carbon – become increasingly vulnerable. Regions once suitable for carbon-sequestering agriculture might become too dry or hot, and forests might die off from novel pests or wildfires. While some new regions might become more suitable for carbon sequestration, the uncertainty and transition costs create enormous risks. In worst-case scenarios, we could actually lose critical tools in our carbon removal toolkit – creating a vicious cycle where warming makes carbon removal harder, which leads to more warming.
The Cooling Bridge We Need to Build
Expanding our climate solution portfolio beyond carbon-centric approaches to include cooling interventions is both inevitable and obvious. My friend Nick van Osdol at Keep Cool wrote a great overview of global cooling methods last fall, but I’ll summarize a few options here:
Stratospheric Aerosol Injection (SAI): Introducing reflective particles into the stratosphere to mimic the cooling effect of volcanic eruptions. This could reduce global temperatures by 0.5-1.0°C within years, not decades.
Marine Cloud Brightening (MCB): Enhancing the reflectivity of low-lying marine clouds by introducing sea salt particles. This could be targeted to protect specific vulnerable systems like coral reefs or ice sheets.
Surface Albedo Modifications: From ice preservation techniques to ocean surface films, these approaches increase reflectivity of Earth's surfaces.
Cirrus Cloud Thinning (CCT): Releasing fine, harmless dust into the thin, wispy clouds high in the sky so their ice crystals grow larger, fall out faster, and the clouds thin out. That lets more of Earth’s heat escape to space, complementing albedo-based methods.
These are not silver bullets. They come with enormous technical, governance, and ethical questions. They don't solve the root cause of climate change. But they might be the only tools we have to prevent irreversible tipping points while carbon removal catches up.
The New Complexity We Must Navigate
Here's where things get vastly more complicated than carbon removal. With the founding of the carbon removal industry, we were mostly dealing with voluntary markets, project developers, and corporations making offset claims. The complexity was significant but containable.
Cooling interventions introduce entirely new dimensions of complexity:
Governance Challenges: Unlike carbon removal, cooling interventions have transboundary effects. Who decides when to deploy? Under what conditions? With what oversight? We need governance frameworks that don't yet exist.
Geopolitical Implications: Cooling methods could affect regional precipitation patterns. Rogue actors or one nation's deployment could negatively impact another's agriculture or water resources. Countries have gone to war over less.
Monitoring Requirements: We need vastly improved monitoring capabilities to track effects, detect unintended consequences, and make evidence-based adjustments.
Ethical Questions: How do we weigh known climate catastrophes against uncertain intervention risks? Who bears those risks? How do we ensure just outcomes across regions?
Funding Models: Unlike carbon removal with its clear "tonne of CO₂" unit (which of course has many challenges), cooling interventions have no obvious market mechanism. Who pays for this? How much? Through what structures?
When I built Nori, we had to create new markets, methodologies, and verification approaches for carbon removal. That was hard enough. But cooling interventions require all that plus international diplomatic frameworks, real-time monitoring systems, and emergency response protocols that don't yet exist.
What Needs to Happen Now
The preparation window for cooling interventions is open now and closing rapidly. Based on current warming trajectories, we'll likely need deployment readiness within 5-15 years. Unlike carbon removal circa 2015, there are a lot of researchers and policy folks who have been looking into these topics for a very long time. So there is a robust body of work. But when it comes to practical deployment of theories, our current state of readiness is woefully inadequate:
Research Acceleration: We need to dramatically scale up research into efficacy, impacts, and monitoring systems. Current funding is minimal and scattered.
Governance Development: We need to begin creating international frameworks for deployment decisions, monitoring, and response protocols.
Funding Mechanisms: We need entirely new financial structures – beyond carbon markets – to fund both research and potential deployment.
Public Engagement: We need honest, evidence-based conversations about risks, benefits, and tradeoffs that move beyond both techno-optimism and knee-jerk rejection.
Coordination Systems: We need mechanisms to align research, policy, deployment, and monitoring across institutions and nations.
I am absolutely not suggesting we deploy cooling interventions tomorrow. I'm saying we need to start building the systems that would allow for responsible deployment when needed. If we wait until cooling is desperately needed, it will be too late to deploy it responsibly.
Moving Forward: A Portfolio for Climate Stability
What we need is a comprehensive portfolio approach:
Emissions Reductions: Continuing to aggressively reduce the total carbon burden.
Carbon Removal: The long-term solution that must reach gigatonne scale by mid-century.
Cooling Interventions: Buying critical time by preventing the worst tipping points while other solutions scale.
These aren't competing alternatives – they're complementary components working on different timescales for different purposes. The portfolio must work together, with each element playing its essential role.
Helping Everyone Coordinate Toward a Common Vision
In the coming articles, I'll explore what a functioning global cooling ecosystem would look like – not to prescribe exact solutions, but to help the many different actors needed in this space understand how they might coordinate:
Part 2: "The Risk-Impact Paradox of Global Cooling" – Examining the unique risk profile of cooling interventions and how it differs from carbon removal.
Part 3: "Who Pays to Cool the Planet?" – Exploring funding models beyond traditional carbon markets.
Part 4: "Governance Without Gridlock" – Designing decision systems for planetary cooling that balance caution with urgency.
Part 5: "Building the Cooling Ecosystem" – A blueprint for how the many necessary components could fit together.
My goal isn't to have all the answers. It's to help create a vision concrete enough that researchers, funders, policymakers, companies, and international bodies can see where they fit and how they might coordinate their efforts.
The Call to Action
For carbon removal practitioners: Continue the critical work of scaling, but engage with the broader climate portfolio discussion. Your expertise in methodology development and verification is invaluable.
For policymakers: Begin developing governance frameworks for research and potential deployment. Stop the reflexive opposition to even studying these approaches.
For funders: Consider how your capital can support not just carbon solutions, but the full ecosystem of climate stabilization approaches, especially the research foundations.
For researchers: Help bridge the knowledge gaps around efficacy, monitoring, and impacts. We need both specific technical advances and integrative systems thinking.
We need to stop treating cooling interventions as taboo and start treating them as a potential necessity. This isn't abandoning carbon removal – it's ensuring we have the tools to prevent catastrophe while carbon removal scales.
I started Nori to help create an entirely new carbon removal industry. Now I believe we need to apply that same category-creation mindset to building a comprehensive climate stabilization portfolio that includes both carbon removal and cooling approaches.
The time for this conversation is right now. The need to buy time isn't theoretical—it's urgent.
Parts 2 and 3 in this global cooling series:
The Risk-Impact Paradox of Global Cooling
This is part 2 in my series on global cooling interventions. You can find part 1 and an outline for the multi-part series here:
Who Pays to Cool the Planet?
When we kicked off the carbon removal industry, we had something (sort of) tangible to sell: a tonne of carbon removed. It has not been easy to build that market, but at least we had a unit. With global cooling interventions, we face a fundamentally different challenge. Who exactly pays to brighten marine clouds? What's the price for preserving an ice s…
Scary, but thoughtfully put together. Excited to read the next part in the series!
A decade ago at a conference I asked about whether we can modify coral to adapt it to warmer water temperatures, and the answer at the time was “interesting idea.” This makes me wonder if anyone has played with that yet.