Skip to content

☁️ "Making Sense of Solar Engineering"

Catalyst with Shayle Kann

Photo by American Public Power Association / Unsplash

Table of Contents

Host: Shayle Kann
Guest: Dan Visioni | Climate Researcher
Category: ☁️ Carbon Reduction | Solar Engineering

Subscribe now

Podcast’s Essential Bites:

[2:02] SK: “For a long time, the term geoengineering has basically been a swear word in certain circles of the climate community. […] But I suspect the tide is starting to turn just a bit on this topic for two reasons. First, with each passing year and each new IPCC report, it becomes clear that some of the worst effects of climate change are coming for us even if we move as fast as we can to cut our new annual emissions to zero. […] Reason two is the recent rise to prominence of the idea of carbon removal or CDR, […] [that] I think is a subset of geoengineering, albeit not the one that most folks think of. We're already talking about hacking the biosphere, when we talk about adding alkalinity to the ocean or building engineered machines to suck CO2 out of the air. […] Is it really so much of a further step to think about adding sulfur to the stratosphere or whitening clouds over the ocean? I'm not sure that it is.”

[4:07] SK: “Moreover, […] the cost of solar geoengineering, in theory, is a tiny fraction of the cost of having the same impact on temperature that you would get out of carbon removal. Specifically, you might be able to get about a half a degree Celsius of global cooling out of stratospheric sulfur injection for a couple of billion dollars, which is basically nothing, comparatively. On the other hand, it raises these enormous questions around ethics and governance. For example, if you can do it for $1 or $2 billion, then almost anyone can do it. And what happens when that becomes a reality?”

[5:53] DV: “The IPCC definition is […]: geoengineering is any kind of deliberate, large-scale intervention into the climate system. […] The key word is deliberate. So […] in general all of our activities affect the climate. But they affect the climate as a byproduct of other things that are happening. Geoengineering would be the deliberate attempt to change the climate in some ways.”

[7:54] DV: “[Solar geoengineering] is the idea that we can intervene on the solar radiation that is incoming on the planet. […] The solar radiation comes in, it warms the planet, the planet then tries to be in equilibrium with the rest of the universe. And so it radiates back part of the energy that it absorbs from the sun. But the high amount of CO2 means that too much of the radiation that is supposed to escape stays in the system and so the planet warms more. So the idea is that the only way we can fix that is by reducing the amount of CO2 that is in the atmosphere. […] [To scale] carbon dioxide removal […] is going to take time. So the idea is, is there something we can do at a much faster scale? So can we intervene in the solar radiation that is incoming […] so that the planet warms up a bit less to begin with? And so we don't experience the effects of global warming too much.

[9:55] DV: “There are absolutely no small scale large scale experiments going on anywhere on the planet. There are a few proposed. […] What we have and a lot of our understanding comes from what we can observe from the natural world and what we call natural experiments. So of the main method, […] is that we know what happens to the planet after big volcanic eruptions. […] The key thing is that they meet sulfate, and they emit sulfate directly into the stratosphere. […] And this sulfate […] tends to oxidize and produce sulfate aerosols. […] We have observed […] that they have cooled the planet for one or two years after the eruption in a measurable way. [This is called stratospheric aerosol injection - basically mimicking volcanoes.]

[18:34] DV: “We would not be just turning back the dial of time to a time where there was less CO2, because the sulfates do cool differently than the CO2 works. […] We wouldn't have the same climate that we would have if we hadn’t emitted all that CO2. […] We would have a climate that globally is cooler. We have no doubt that the sulfate would kill the planet. But […] we're not sure yet about what the regional this precise regional outcomes would be. […] And then there are many, many other things that we still need to study.”

[22:50] “Whenever you have very big ships going through the ocean, you can see the track that they leave, because they emit particles as well. And so what these particles do over the ocean in the very low levels of the atmosphere, is that they sometimes […] make it more likely for clouds to form. So these marine clouds are very fake white, fluffy clouds that tend to reflect a lot of the solar radiation. And so there have been observations and study seeing, looking at this very tiny scale effect of ship tracks. And so the idea for these has been can we kind of make it more likely for these clouds to happen? [This is called marine cloud brightening.]

[25:35] DV: “Space mirrors […] would prevent […] again a fraction of the solar radiation from coming in. In that case, aside from having the same issues that stratospheric aerosol injection have about the difference of a climate with high CO2, but less sort of radiation, there's also the technological problem of […] hav[ing] large, gigantic controllable space mirrors. […] For now, we have no clue how to do that.”

[27:47] DV: “Cirrus cloud thinning is even more complicated. […] Not all clouds help cool the planet. […] There are clouds much higher up in the troposphere, where the temperatures are much, much, much lower, that are actually made of ice crystals. And these ice crystals are […] transparent to solar radiation, but they are not transparent to infrared radiation, so the radiation that comes out of the planet. And so they do contribute to the greenhouse effect, as they do trap part of the radiation. But the main issue is that we're really not sure how much. […] We really still have a hard time figuring out the magnitude of the warming that is produced by the cirrus clouds. But assuming that we knew that, the idea is that we could somehow reduce the concentration of the cirrus clouds, these ice clouds in the upper troposphere […]. And in this case, really, we are still at a point where we're trying to understand whether we get the physics right.

[38:01] “Solar geoengineering […] comes at the point where we realize that we can scale CDR, but slowly, and it's going to take a lot of effort, and that we need to do something in between. We need to do something to do what we call peak shaving. […] It could be that solar geoengineering could be the solution that allows us to stay below 1.5 while we do all of the other stuff that is absolutely necessary.”

Rating: ☁️☁️☁️☁️

🎙️ Full Episode: Apple | Spotify | Google
🕰️ 45 min | 🗓️ 06/16/2022
✅ Time saved: 42 min

Subscribe now