Climate Expert: Stop Talking About "Geoengineering"

Term is a distraction from crucial research on climate interventions

8 min read

Stratospheric view of the Earth

The leaders of the world have just returned from the UN’s latest climate change summit, COP26, in which the countries that have signed on to the Paris Agreement upped their commitments to fight climate change. Everyone solemnly agreed, again, to follow the science, which has shown in exhaustive detail that humanity will suffer from heat, fire, floods, and droughts if the world warms beyond 1.5° C above pre-industrial levels.

Yet if countries continue on their present course, the world will likely have warmed by 2.7° C by the year 2100, according to Climate Action Tracker. If they meet all the pledges they’ve made for emission reductions by 2030, global temperature rise will be at 2.4° C by then. Hardly the breakthroughs we need to stave off disaster.

In light of this situation, there’s increasing talk of actions that governments can take beyond reducing greenhouse gas emissions—actions that could either remove existing greenhouse gases from the atmosphere or reduce the amount of sunlight coming into the atmosphere. Nobody’s proposing relying solely on such tactics, but they could potentially help the planet in the short-term.

Such approaches are usually called geoengineering, and they’re controversial: Many people worry about the unintended consequences of interfering with nature on a global scale. But Kelly Wanser, the executive director of the non-profit Silver Lining, argues that humanity is already interfering with nature on a global scale; that’s what climate change is all about. She spoke with IEEE Spectrum about her work in encouraging basic scientific research on climate interventions.

IEEE Spectrum: What role does Silver Lining play in climate research or advocacy?

Kelly Wanser: Silver Lining’s focus is on near-term climate risk: the exposure that we have to climate change between now and the middle of the century. The IPCC report released this past August said that in all of the realistic scenarios that they look at for climate change, warming continues to increase between now and 2050. And right now, we don’t have enough ways to significantly reduce that warming.

Portrait of a blonde woman in a black shirtKelly Wanser

Spectrum: Where does the name of the organization come from?

Wanser: It’s partly a play on words. One approach to reducing warming has to do with brightening clouds with salt from seawater. But it’s also a way of indicating that there is hope and possibility in navigating the dangerous part of the climate change situation.

Spectrum: I’ve been reporting on this topic recently, and I think I irritated a few researchers by using the term “geoengineering.” Do you object to that term, and if so, what term do you prefer?

Wanser: We do object to it, because we don’t think it’s a good reflection of what is being proposed in these rapid responses to climate change. In 2015, the U.S. National Academy of Sciences published a report on these types of technological approaches to reducing warming or reducing greenhouse gases, and the term that they arrived at was “climate intervention.” It’s a useful term because it speaks to the problem it’s aimed at, climate, and expresses the uncertainty involved—we’re trying to influence a system, but we don’t have a high degree of control, like we would in an engineering context.

We actually conducted a public poll on the terms “geoengineering” and “climate intervention” and found that people were better able to comprehend what was meant by climate intervention, and also were less fearful.

Spectrum: When you talk about climate interventions, are you including carbon removal and sequestration in that category?

Wanser: We do include that in the broad category. But we focus on it less, because we’ve opted to focus on approaches that are likely to be most rapid and most likely to help address near-term risks. We’ve also focused on the parts of the portfolio where there are fewer people and fewer investments that are moving things forward. So, we focus significant energy on solar climate intervention, or sunlight reflection. We do some work on carbon removal, but that’s pretty big space with a lot of investment. Which is good.

Spectrum: When you talk about the rationale for research on climate interventions, do you start with moral arguments or economic arguments?

Wanser: We start from the point of view of public safety, which is a concept in international environmental law and environmental law in the United States. We’re really focused on the fact that we have quite a serious safety problem—potentially a catastrophic safety problem—in terms of human life, displacement and suffering, and the natural systems that we rely on.

The projections are that up to a billion people could be displaced between now and 2050, meaning that many parts of the world will become uninhabitable by then. What do we have to offer these billion people? We see it as similar to the ozone hole problem, where we really needed a tight, science-based focus on the limits to human inputs to the system--and howthose inputs affected the ozone layer’s ability to keep people safe.

Spectrum: You’ve spoken before about tipping points: the idea that we may exceed thresholds in natural systems and thus cause drastic and irreversible changes. Which ones do you worry about?

Wanser: I’ll focus on the one for which there is the most robust information. The Amazon rainforest is called the lungs of the planet because it gives oxygen back to the system and takes in a lot of CO2. But a combination of deforestation and warming pressure have caused the Amazon to now release more greenhouse gas than it absorbs, which is considered to be a big accelerant of climate change.

We are working with climate modelers to try to figure out how that changes the projections. But the IPCC report that came out in August does not include this newly discovered state of the rain forest. And, therefore, the curves in that report’s [warming] pathways may not reflect the real amplification this might create. In almost all previous projections for climate, tipping events like these were far in the future. For the Amazon rain forest, the climate modelers that we talked to said there were almost no climate simulations where the rain forest tips in this century.

Spectrum: You’re saying the situation is even more dire than we thought. And yet there’s a lot of resistance to research on climate interventions that you say could help with near-term risks. I typically hear two critiques. The first is the moral hazard argument: If we embark on this research, it will undermine attempts to reduce greenhouse gas emissions. People will think it’s a get-out-of-jail-free card. How do you guys respond to that?

Wanser: Well, I usually respond with some sympathy for it. If we had started ratcheting back greenhouse gas emissions in the 1980s, that would have been the wisest and the safest thing to do. I like to use the analogy of medicine. It’s not very smart to not take simple precautions and to let the patient get sick. But when the patient is very sick, then preventative measures like healthy diet and exercise don’t help effectively enough or quickly enough. The treatment options aren’t the same when a patient is sicker, and it appears we have quite a sick patient now.

Spectrum: The second critique I usually hear is that we will never understand enough about our complex climate systems to be able to intervene safely, and that we’re guaranteed to mess things up and create massive side effects. How do respond to people who say the precautionary principle applies here?

Wanser: This is one of the reasons that we don’t like term geoengineering. If you think of it as something wholly new and different, then there’s this understandable thought: Why would we do something totally new and different than we don’t understand? But a dirty, unmanaged variation of this is happening already.

Two graphs labelled Contributions to warming based on two complementary approaches showing red and blue bars based on contributions to warmingHumanity is already reducing global warming... by spewing pollution into the air. IPCC Report: Climate Change 2021

The 2021 IPCC report includes a chart where they show the human influences on the climate system, with pink bars for warming effects and blue bars for cooling. The largest blue bar is the effect of pollution particles on clouds. [[The particles attract water to increase the number of droplets in clouds, and those clouds reflect more sunlight away from the Earth.]] It’s a cooling effect and it’s happening all over the world as a result of pollution from factories, ships, and cars. We’re planning to remove that pollution, so it would be wise for us to understand that effect. And it would be interesting for us to think about whether there’s a clean variation that we might want to replace it with. For example, some scientists are proposing to use a salt particles from seawater to brighten clouds over the ocean and send more sunlight back to space.

If you think about it that way, then this isn’t a question of should we do something totally new or not, but how do we manage this situation that we already have, which includes these existing dynamics, these variations of things that are happening now.

Spectrum: In September, Spectrum published an article by the researchers working on that marine cloud brightening project. But do you want to sum up what they’re doing?

Wanser: It’s one of the few research efforts in the world that is looking at the process-level science around these climate intervention techniques for reflecting sunlight from the atmosphere: How would it actually work? How would you disperse the particles? How would they move in the atmosphere and affect the reflection of sunlight? For years, they have been developing technology for local dispersal and figuring out how to make the size and quantity of particles they think will work best. Now they have a large scientific collaboration to do [atmospheric and climate] modeling from very local to regional to global scales and to maybe step out and spray at very small scales to study those dynamics and inform the models.

It’s exciting because they have the potential to do really important science about how pollution is impacting clouds and climate and also because they can likely determine, in a fairly reasonable amount of time, whether or not marine cloud brightening might be an option to significantly reduce warming.

Spectrum: Imagine that the researchers find that marine cloud brightening is effective at reflecting sunlight and doesn’t have negative impacts. How would it be implemented?

Wanser: There are three parts of the world that have large banks of marine stratocumulus clouds that are very susceptible to this effect. Scientists propose having ships or autonomous vessels that would cruise around and spray particles in these regions, maybe be in the low-digit thousands of ships. Their goal would be to brighten these clouds by something like five to seven percent, so probably not in a way that’s visible from the ground, and maybe not even visible from space.

Spectrum: Where are these three parts of the world?

Wanser: One of them is in the Pacific off the west coast of North America, another is off the west coast of South America, the third is off the coast of southern Africa.

Spectrum: The marine cloud project deals with adding particles to low-level clouds, but I also wanted to get your perspective on the SCoPEx project from Harvard, which wants to test the effect of stratospheric particles. They’d hoped this past year to simply test the technology platform, not to actually do any kind of experiments with spraying reflective particles. And yet the research group’s advisory board stopped them and said they had to postpone it and think it through more. What’s your perspective on both that project and that decision?

Wanser: We think that this early science is really important to inform decision-making. This was meant to be a test of a research apparatus, it wasn’t even a test of something that would release any material. This was a balloon for research—like the balloons that go up every day to do atmospheric science.

The problem is, this valuable early science was positioned as a moment for a societal decision about research in this category. The testing they proposed wouldn’t have had any environmental impact or impact on people. So the basis for the decision was not scientific; it was really about a small set of people’s opinions about whether or not this kind of research should go forward. While the intentions were good, they inadvertently set up an undemocratic situation where a very tiny group of people are deciding whether scientific information would be available for everybody else.

We think that scientific independence and integrity is really important, especially in this research. We need scientists doing independent science, and when they have generated a lot of information for people around the world to review, we then need the societal moment where everybody can weigh in.

The Conversation (3)
Stanley Harrison
Stanley Harrison03 Dec, 2021

It is very interesting that the volcanic affect is so low on the graph. Also, there is no indication that shifting magma can cause considerable havoc. By 2100, the decline of humanity will be the greatest problem. At the current rate of decline, there will be no need to even consider climate change.

Russ George
Russ George21 Nov, 2021

About the Marine Cloud Brightening that is proposed in this IEEE article, of course it will work but it will require vast machinery and expense and decades to develop and deploy. Ocean Pasture Restoration (OPR) is proven at scale and immediately deployable. It's replenishment and restoration of plankton blooms, ocean pastures, will accomplish marine cloud brightening at a vast scale as a side benefit. Our ‘OPR Machines’, the blooming ocean pastures, just happen to be about 50,000 sq km in size. As the restored sustainable photosynthesis naturally breathes out vast amount of cloud nucleating phyto-chemicals marine clouds are brightened and increased in area. The greatly diminished state of ocean pastures today is a major cause of diminished ‘albedo’ on this blue planet, and that loss is a major component that is driving global warming. The first and foremost benefit of OPR is that it Brings Back The Fish in vast multitudes along will all of ocean life. Read this fine article about OPR at

FB TS17 Nov, 2021

IMHO, all geoengineering ideas are band-aid solutions, which just mask/hide the problem, instead of really curing it!

So, the underlying problem would keep getting worse, until any/all geoengineering does not work, either!

& no doubt there would be unforeseen side effects!

(Or, can we really claim, we completely/perfectly understand everything about climate now, so we can always predict it completely/perfectly?)

& who will be willing to pay astronomical (initial & continuous) costs?

Who will be willing to pay for any damages/losses/failures?

Why not focus on really practical and risk-free solutions like, restoring forests of Earth, reducing fossil fuel usage, increasing solar/wind/hydro-power (& keep researching better nuclear fission & fusion tech)?

(Which all would have countless side-benefits, besides of saving climate!)