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We have a massive toxic spill into the atmosphere. And the immediate most damaging effect of that is heat energy trapped in the system. And so the question is, do you try to do something to counter that or to abate it?

Kelly Wanser

How long do you think it’ll be before we’re able to bend the weather to our will? A massive rainmaking program in China, efforts to seed new oases in the Arabian peninsula, or chemically induce snow for skiers in Colorado.

100 years? 50 years? 20?

Those who know how to write a teaser hook for a podcast episode will have correctly guessed that all these things are already happening today. And the techniques being used could be turned to managing climate change as well.

Today’s guest, Kelly Wanser, founded SilverLining — a nonprofit organization that advocates research into climate interventions, such as seeding or brightening clouds, to ensure that we maintain a safe climate.

Kelly says that current climate projections, even if we do everything right from here on out, imply that two degrees of global warming are now unavoidable. And the same scientists who made those projections fear the flow-through effect that warming could have.

Since our best case scenario may already be too dangerous, SilverLining focuses on ways that we could intervene quickly in the climate if things get especially grim — their research serving as a kind of insurance policy.

After considering everything from mirrors in space, to shiny objects on the ocean, to materials on the Arctic, their scientists concluded that the most promising approach was leveraging one of the ways that the Earth already regulates its temperature — the reflection of sunlight off particles and clouds in the atmosphere.

Cloud brightening is a climate control approach that uses the spraying of a fine mist of sea water into clouds to make them ‘whiter’ so they reflect even more sunlight back into space.

These ‘streaks’ in clouds are already created by ships because the particulates from their diesel engines inadvertently make clouds a bit brighter.

Kelly says that scientists estimate that we’re already lowering the global temperature this way by 0.5–1.1ºC, without even intending to.

While fossil fuel particulates are terrible for human health, they think we could replicate this effect by simply spraying sea water up into clouds. But so far there hasn’t been funding to measure how much temperature change you get for a given amount of spray.

And we won’t want to dive into these methods head first because the atmosphere is a complex system we can’t yet properly model, and there are many things to check first. For instance, chemicals that reflect light from the upper atmosphere might totally change wind patterns in the stratosphere. Or they might not — for all the discussion of global warming the climate is surprisingly understudied.

The public tends to be skeptical of climate interventions, otherwise known as geoengineering, so in this episode we cover a range of possible objections, such as:

  • It being riskier than doing nothing
  • That it will inevitably be dangerously political
  • And the risk of the ‘double catastrophe’, where a pandemic stops our climate interventions and temperatures sky-rocket at the worst time.

Kelly and Rob also talk about:

  • The many climate interventions that are already happening
  • The most promising ideas in the field
  • And whether people would be more accepting if we found ways to intervene that had nothing to do with making the world a better place.

Get this episode by subscribing to our podcast on the world’s most pressing problems and how to solve them: Type 80,000 Hours into your podcasting app. Or read the transcript below.

Producer: Keiran Harris
Audio mastering: Ben Cordell
Transcriptions: Sofia Davis-Fogel

Highlights

Existing climate interventions

Kelly Wanser: So as the earth system warms, a couple of the big side effects that are causing problems for people are changes in rain and precipitation. Either producing drought and problems with water, or producing flooding and storm surges. And in both cases, what we have in lots of different parts of the world are efforts to disperse particles into the cloud layer, either to make rain or snow, or to induce precipitation offshore, to prevent flooding. And so there’s a massive rainmaking program in China, in an area the size of Alaska, to increase precipitation. If they scale that up to the size that they’re expecting to, that would be a big enough weather modification effort to affect atmospheric circulation and weather in other places.

Kelly Wanser: So you start to get into these bottom-up efforts, which aren’t exactly the same mechanism as what we’re talking about to cool the climate, but they’re similar. And we actually have quite large-scale weather modification activities in the United States, that most people aren’t aware of. So we’re hearing that, in Colorado, they dispersed particles into the cloud layer to increase the snow pack. Not just for skiing, but actually at a large enough scale to try to improve the water table. So these are the kinds of things that are escalating. And then in Indonesia they had a couple of different rounds of injecting particles into clouds offshore to try to induce rain, to reduce flooding. And so we anticipate that as the earth warms and climate impacts grow, these will escalate. And then there was a very small test over the Great Barrier Reef, that was really more about studying the mechanism for what you might do to increase clouds and cooling over the Great Barrier Reef, to try to protect it.

Kelly Wanser: And so those things are starting to emerge. At the same time we have some accidental cooling happening. What many people aren’t aware of is that the particulates in our pollution…so not the greenhouse gases, but actually the dirtier stuff that they’re concerned about us breathing, that often has the effect of mixing with the cloud layer to make clouds brighter and provide some cooling. And you can see this from space in the shipping lanes as they traverse the clouds and create big streaks. And globally scientists believe that this is causing a significant cooling effect. So we have an accidental version of the kinds of things that our organization helps people look into, this cooling effect, going on as well.

SilverLining's approach

Kelly Wanser: So my organization, SilverLining, follows the recommendations of the scientific community. We do some of our own review, but where our scientists landed… There were a couple of assessments that asked that question: If we needed to cool the planet quickly, or counter global warming quickly, what are the best options? And they looked at things from mirrors in space to shiny objects on the ocean, to materials on the Arctic, to things like putting particles in the stratosphere or brightening clouds. And one of those assessments was in the United Kingdom, the Royal Society, back in 2012, and then in the United States, by the National Academies in 2015. And so where they landed was that the most promising approach was leveraging one of the ways that the earth system regulates its temperature, which is the reflection of sunlight off of particles and clouds in the atmosphere.

Kelly Wanser: And so, without getting into too much detail, the surface-based approaches tend to be much lower in terms of effectiveness for a variety of reasons, including the fact that clouds are in the way. And they also are more invasive in terms of their potential to interfere with ecological systems. The space-based approaches were actually pretty far off from the kind of engineering that would be required, because the area mass that you would need to affect sunlight coming to Earth is actually massive. So even though people think well, we put lots of satellites up, here we’re talking about like a billion square meters out of the apex between the earth and the sun. And so the ideas I’ve heard about are self-replicating robots who could mine an asteroid and then build a filter.

Robert Wiblin: At that point you should just leave Earth and go colonize Mars maybe.

Kelly Wanser: Pretty much. When they talk about increasing the reflection of sunlight from the atmosphere, they’re talking about 1% or 2%. So it’s a slight modulation of the way particles in clouds are reflecting sunlight, in Earth terms. And so it becomes both more feasible and less invasive. And then it turns out that we’re doing it already, in a way that we don’t understand very well.

Doing good by accident

Robert Wiblin: I’ve noticed that people don’t seem to raise objections to climate intervention so long as it’s unintentional. People are worried about climate change, but not as much as they’re worried about geoengineering. And maybe they have some concerns about the cloud seeding stuff that we were talking about earlier, but they don’t seem nearly as worried about that as the proposals that people have for actually deliberately making things better. Can we get these things to happen just by making them an accident? Like maybe we have to find some other reason that we want to throw salt up into the clouds, some way that’s profitable, that has nothing to do with making the world a better place. And then maybe by accident, we can make the world a better place and people will accept that. Does that make sense?

Kelly Wanser: I hadn’t really quite thought about it that way. That’s fascinating because oftentimes the correlation with it is pollution. And of course, they’re trying to get rid of those particles from pollution. Figuring out whether you should have an ancillary benefit that people would buy into… One of the things that we ran into with marine cloud brightening was once the rabbit is out of the hat or the cat is out of the bag, people were like, “Well, you have to call it geoengineering or you have to say at least part of what it does.” It’s pretty hard to get people to decouple that. We focused a little bit more on trying to clarify that some of these things are going on and so that is the… Is your objection that it’s intentional? Or is your objection around safety?

Common objections

Kelly Wanser: The primary objection that we get is a concern that this will be a pacifier for society to… One more thing that says, “Oh, we can wait. We don’t need to take action on the root problem.” And the root problem is still that our atmosphere is a toxic waste dump full of greenhouse gases and it’s absolutely imperative that we bring those down as fast as we can. There isn’t an intervention that solves all sides of that problem. And so there’s a legitimate concern that people have that this will be another delaying feature. And I think 50 years ago in the ’70s and ’80s when the climate problem was early, and scientists could recognize exactly where it would go if you kept going, just turning the knob down on greenhouse gases would make eminently more sense than thinking about putting stuff up in the atmosphere.

Kelly Wanser: And at that time, I think it would be very reasonable for people to say, “Why on earth would you work on that? Let’s turn this down. Let’s never approach where you would need to go.” Now the situation is different. We’re driving up to the cliff’s edge, we’re driving up to that place that scientists never thought we would go. And so we have to think about, is it really the case that talking about these interventions will reduce society’s motivation? There were some social scientists at Harvard who actually studied this and they felt like it could actually propel urgency. If you think about having a medical condition and they tell you, “We’re looking at some pretty invasive treatment for that condition if it keeps progressing,” that’s what we’re here to say. And so there are some people who think that it could actually have the opposite effect and motivate society to say, “Oh, the problem is really that serious.”

Is global coordination possible?

Kelly Wanser: The most successful areas of environmental cooperation, even other areas of cooperation like the ballistic missile treaty, the ones that are very science-evidenced and data-focused have a track record of being most successful. And the ones where the politics rules or philosophy rules…they’re less equipped to do rigorous science, and they tend to be a lot less successful. And so even the IPCC is somewhere in between. But the Montreal Protocol is rigorously science focused, they follow the evidence on what’s happening to the ozone layer.

Kelly Wanser: And so I think we really think… And again, I’ll start by saying, because sometimes I find myself in a fundamental argument between pessimism and optimism, we will not proceed on the basis that something is impossible. That’s not a concession we will make. We will say that, “As climate change progresses, and looking at these things, we step forward on the basis of what are the most successful examples of things that are really hard getting done.” But if the world can agree not to set off nuclear weapons, which they have so far since World War II, I’m not sure this is a harder problem in terms of managing what we need to do here.

Robert Wiblin: It’s a very interesting model you’ve got there where I guess you’re saying if the discussion all becomes about philosophy and ethics, and I guess just humanities things where people naturally disagree and could talk forever, then maybe that just leads to lots of disagreement. But if you can bring all of the engineering/technical/scientific information to the table and get everyone focused on that, then maybe that would unlock some agreement, because people would see things that could be done that would be mutually beneficial — or at least don’t trouble people very much. But if you’re super uncertain about the consequences, then it’s very likely that someone is going to raise an objection. Perhaps focusing on science brings a little bit more clarity.

Kelly Wanser: I think that’s a really good point. And it just grounds the conversation into where the real issues are. We tend to be a bit optimistic on that front, but we also… I find myself having to be very straightforward about what we’re solving for, because not everybody’s solving for the same thing. We are solving for minimizing loss of life, minimizing human suffering, and keeping natural systems stable. And so we’re very concerned about evidence related to that, projections related to that, where those thresholds are that we shouldn’t cross. Not everybody is solving for that. Some people are solving for the world to make decisions in a certain way. Some people are solving as a priority for other kinds of economic or disparity objectives. And we care about those things, but we’re very focused on the fact that people can’t make decisions if they’re not alive. And we’re willing to be very overt that that’s what we’re solving for. And then how do we get information about that? How do you rigorously assess options about that?

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About the show

The 80,000 Hours Podcast features unusually in-depth conversations about the world's most pressing problems and how you can use your career to solve them. We invite guests pursuing a wide range of career paths — from academics and activists to entrepreneurs and policymakers — to analyse the case for and against working on different issues and which approaches are best for solving them.

The 80,000 Hours Podcast is produced and edited by Keiran Harris. Get in touch with feedback or guest suggestions by emailing [email protected].

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