Volts podcast: Dr. Ye Tao on a grand scheme to cool the Earth

In this episode, Dr. Ye Tao discusses his vision for combatting climate change by using fields of mirrors that reflect solar radiation.

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David Roberts

Geoengineering — using large-scale engineering projects to directly cool the Earth’s atmosphere — is an intensely controversial topic in climate circles. On one hand, such schemes strike many people as dangerous hubris, interfering with large-scale systems we don’t fully understand, risking catastrophic unintended consequences. On the other hand, there is good reason to believe that even a wildly successful program of decarbonization will not be enough to avoid devastating levels of heat in the atmosphere.

Dr. Ye Tao was early in his career as a researcher at Harvard’s Rowland Institute, working on nanotechnology, when he became gripped by the problem of climate change. As he dug into the research, he concluded that even rapid decarbonization — especially insofar as it reduces the aerosol pollution that temporarily cools the atmosphere — would leave the Earth roasting in levels of heat hostile to most life forms.

As he reviewed available options for carbon capture and geoengineering, he realized that none of them were safe or scalable enough to do the necessary cooling work in time. So he came up with a technique of his own: mirrors.

The MEER project — Mirrors for Earth’s Energy Rebalancing — is a nonprofit established to advance Tao’s vision, which involves covering some mix of land and ocean with fields of mirrors. The mirrors would reflect solar radiation, and thus heat, back up out of the atmosphere. If 10 to 15 percent of developed agricultural land could be covered with mirrors, Tao has calculated, it would return Earth’s heat to safe preindustrial levels, providing a range of local benefits to agriculture and water in the meantime.

It’s a brash idea, somewhere between crazy and obvious, and I was excited to hear more from Tao about why he thinks it’s necessary, how it would work, the materials that would be required, and how the MEER framework changes the way we view carbon dioxide in the atmosphere.

Alright. Ye Tao. Welcome to Volts. Thanks for coming on.

Ye Tao

Yeah, thanks for inviting.

David Roberts

Ye I have to confess when I first invited you on the pod, I had not yet really done a deep dive into into the MEER Project, and I was just sort of thinking, "Oh, a bunch of mirrors. How novel. That sounds fun. Let's talk about that." But I've spent a while now digging in and listening to more of your presentations and reading more, and there's really a lot going on here. There's a lot going on here. The mirrors are at the end of a sort of chain of reasoning that in many, many ways contradicts conventional wisdom about climate change.

So I do want to get to the mirrors. I'm excited to talk about the mirrors, but let's do a little background building first. So I want to start with, it seems like the key to understanding your whole framework here is the distinction between CO2 and heat. We sort of conflate carbon and heat. When we talk about climate change, what's the problem? It's more carbon, and carbon causes heat. How do we reduce heat? We reduce the carbon dioxide emissions. We sort of have those coupled in our mind. And you say it's important to decouple them. So talk a little bit about why we need to keep them conceptually distinct, and then also decouple them in terms of the physics of the system.

Ye Tao

Okay, yeah, that's a good place to start. It's true that we created this problem by emitting CO2, and it's important to shut it down as quickly as we can manage, practically. And in the Earth system, everything is basically linked. So it's only natural that when you perturb one important component to a very significant extent, such as CO2 concentrations, you should expect some downstream consequences — and the most urgent of which is overheating of the planet. And heat is really the driver of weather patterns and precipitation patterns. So when you have excess thermal energy that's really different from the state Earth was before the CO2 perturbation, that you can expect downstream extreme events and also perturbation to the biochemical cycle.

And if we look at the responses of different organisms and plants, insects, and mammals, and how they respond to individual perturbations in CO2 versus temperature, universally they really suffer when temperature gets ramped up to a few degrees above their normal temperature niche values. But in terms of CO2, essentially most species, like 90% plus or more, are actually not perturbed really by the current increase in CO2 levels. So basically, we initiate this avalanche by burning CO2. But the real environmental stressor that's really creating havoc are a combination of overheating and the resulting drying of land and moisture.

David Roberts

So what we talk about as the effects of climate change are the effects of heat, basically, our heat playing its way through the system. And is it safe to say then that we care about CO2 in the atmosphere more or less only as it relates to heat? Only insofar as it brings more heat, right. Because in and of itself, as you say, it's not, I mean, I'm sure there's some level of concentration that's dangerous, but the levels of concentration we're talking about are not dangerous in and of themselves. Is that fair?

Ye Tao

Well, we'd have to be a little bit more careful and include a timeline. I would say, like in the near future, next 50 years, assuming that we're emitting and growing economy on current trajectory, then the predominant parameter is heat. That's going to basically shut everything down before we're able to continue. But if we were, somehow, we're able to manage to prolong this fossil fuel economy then by the 2070s, 2080s, ocean acidification would then also become a potentially dangerous environmental stressor for marine ecosystems. But the logic is that it's very highly unlikely for society, or civilization, to really survive to that point on our current emission trajectory.

Therefore, we really need to focus on both decarbonizing safely and also dealing with heat. So I mentioned that we initially started this heating process by turning up CO2. And that there are many parameters in Earth system are interlinked. But it's logically just not correct to say that the best way is to use this single CO2 knob to address the heat or moisture. There are other knobs that are higher leverage, essentially, for the same input in resources, energy, and time. And we're stressed on all those fronts. There's much better ways to address the most imminent danger of environmental overheating than looking at conventional CO2 or methane mitigation.

David Roberts

Right. So CO2 is the knob that turned heat up, but it's not necessarily the ...

Ye Tao

Only knob that we have.

David Roberts

Or most efficient knob for turning it down. And you go beyond that to say, that even if we switched to 100% renewable energy tomorrow, you think we would still pass heat thresholds, that would be devastating. Explain that a little bit.

Ye Tao

So currently Earth is on a heating trajectory, and when something is heating, that's because