The Promises and Risks of a Controversial Approach to Cooling the Planet

On a recent episode of The World Unpacked, host Sophia Besch spoke with Cynthia Scharf, a senior fellow at the International Center for Future Generations and former senior strategy director for the Carnegie Climate Governance Initiative. They spoke about the possible benefits and many unknowns of solar geoengineering (also known as solar radiation modification), an emerging technology that aims to reflect sunlight back into space to cool Earth.

An excerpt from their conversation, which has been edited for clarity, is below.

Sophia Besch: What is the promise of solar geoengineering?

Cynthia Scharf: Imagine a parasol or suntan lotion sprayed all over your body. And imagine this body is the planet Earth. There is a parasol above you at the beach. What that parasol is made of is aerosols that are flying high in the stratosphere, that are reflecting sunlight as it comes down to Earth, and therefore that cools the Earth. Scientists are fairly confident that this would work based on natural analogs they see in major volcanic explosions, for example. [In this case,] huge amounts of aerosols are released, they go into the atmosphere, and the temperature is cooled very quickly.

The reason there is growing interest in this topic is because we see climate impacts worsening. And most scientists looking at these estimates would agree this would present catastrophic changes to life as we know it. That’s why there is growing interest in something that might literally turn down the heat.

Solar geoengineering does not take care of all of the various impacts of climate change. It is not a solution. It is not a substitute for all of the things that for thirty years now we’ve been hearing scientists say we must do, but which we’ve failed to do. What this is is at best a supplement to doing all of those other things.

Sophia Besch: How close are we to some actors deploying this technology?

Cynthia Scharf: With solar geoengineering, the science is the easy part. Scientists estimate it would take probably at minimum ten years to build approximately 100 aircraft that have engines that enable a plane to fly twice the height of commercial airspace and to release on a 24/7 basis a massive amount of aerosols into the stratosphere.

Those planes currently do not exist. To create a fleet of 100 planes with this kind of an engine would take at minimum ten years. Of course, if there was a directive from the president or a major power that said get it done faster, perhaps that could be done. But ten years is about the time.

Sophia Besch: What is the thinking on global governance for this technology?

Cynthia Scharf: What makes this issue so confounding and vexing from a governance perspective is really who decides what the global thermostat should be? And if this type of solar geoengineering were ever to be used, it would affect every country in the world, but perhaps not equally. So there could be some winners and there could be some losers.

Going back to the question of governance right now, one of the greatest risks of geoengineering is that there simply is no comprehensive governance for this technology. Most of the research is being done in the U.S., the EU, and the UK. But China has a program. Brazil has actors. India has scientists working on this. There is research, significant research happening in the Global South. But where would a decision on how this is to be used be made? There is no UN body that would own this. There’s no natural home for this issue. And if someone were to do an outdoor test of significant scale or to deploy, it would cause chaos. Because there is no one organization where this issue could be discussed that would cover all its dimensions.

Sophia Besch: What is the responsibility of the generation in power now to future generations with regard to these technologies—especially solar geoengineering?

Cynthia Scharf: I feel very strongly that young people need to learn about this technology and what it might bring in terms of potential risks and benefits. They need to be a part of this conversation setting the governance agenda.

If solar geoengineering were to be used, it would not be turned on and off like a faucet. It would be used for decades, if not a century or more. Once the commitment is made, it is being used for the rest of our lifetime, proceeding perhaps beyond this century or more. So the younger generation absolutely has a vested interest in being part of governance about this.

Sophia Besch: When you say that once we’re in, we’re committed, what do you mean?

Cynthia Scharf: Solar geoengineering is only masking one symptom: the rise in temperature and the effects from that. It is not solving the problem.

The only way you can bring down the global temperature is by removing huge amounts of carbon that are already in the atmosphere. This is called carbon dioxide removal. Right now, the technology and the research on removing this carbon is in its infancy. There is also currently not a price on carbon that would enable the private sector to come in at scale.

So what I’m saying is, because we can’t draw out that carbon quickly, it’s going to take decades, if not a century at the current pace of technology on carbon removal. Once we have solar geoengineering, we’re staying with it until there’s a method to actually address the cause of the problem. Right now, getting that carbon out of the atmosphere is akin to sipping a lake through a straw.

Sophia Besch: This is where we get into the termination shock idea: once we start this, we can’t stop, because the consequences might be dramatic if we did.

Cynthia Scharf: Right. One could stop solar geoengineering after one started. But the effect, if it was done at a global level, would be devastating on biodiversity. Plant species and animals can’t respond as quickly as these wild shifts in temperature would indicate. Scientists are very concerned that this termination shock would be one of the greatest risks of this technology.

One of the questions raised very often when people hear about this is: well, aren’t we playing God? And if you look back in history, you see that there have been myths in many cultures looking at these issues of what is humanity allowed and not allowed to do. So looking at a myth like Pandora’s Box, that’s somewhat analogous to the situation we’re facing now, maybe solar geoengineering is that box and it might be beneficial, but it could cause potentially devastating risks. We just don’t know.

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