Bill Gates Is Thinking About Dimming the Sun

Caroline Delbert
·5-min read
Photo credit: Ron Wurzer - Getty Images
Photo credit: Ron Wurzer - Getty Images

From Men's Health

Bill Gates, who recently suggested the world should eat 100 percent synthetic beef and said bitcoin is bad for the planet, has set his sights on a new foe: the sun.

Gates and other private donors are backing Harvard University’s Solar Geoengineering Research Program, which will soon launch a new study researching the efficacy of blocking sunlight from reaching Earth’s surface.

This week, the influential National Academies of Sciences, Engineering, and Medicine (NASEM) also released a new report urging the U.S. government to spend at least $100 million to study solar geoengineering, a controversial technology.

What is solar geoengineering, anyway, and why are scientists suddenly interested in – and concerned by – the concept?

Solar Geoengineering, Explained

Geoengineering is a blanket term for technologies that try to alter Earth’s physical qualities on the largest scale possible. One example is cloud seeding, where airplanes flush clouds with particulate matter in order to coalesce into rain. Carbon capture, where emissions are taken and sequestered beneath Earth’s surface, is another major form of geoengineering.

Scientists have devised multiple ways to block sunlight from reaching Earth’s atmosphere or surface. These are gathered under the umbrella term “solar geoengineering.” The most common and studied method is to reflect sunlight away from Earth using aerosol particles in the atmosphere, but until now, this has been seen as more of a fringe idea. It’s the instigating event of the 2013 film Snowpiercer, for example, where blocking sunlight has turned Earth into a lifeless ice ball.

While the mechanism of an aerosol solar geoengineering study is simple – the physical structure of aerosol particles literally blocks and scatters light – the reality is more complex.

Remember the 2010 eruption of an Icelandic volcano that blocked the entire sky all the way into Europe? That was an atmospheric aerosol event. The meteor strike that might have killed the dinosaurs blanketed the Earth in a layer of aerosol dust. Almost any everyday substance can be aerosolised in the right conditions – the term is simply any airborne fine particulate that can float in clouds like a gas.

Why Do Scientists Want to Study This Now?

Solar geoengineering with aerosols runs head into the fact that aerosols, like ozone layer-destroying chlorofluorocarbon (CFC) spray aerosols, have often been a contributor to climate change. Scientists say this lack of concrete information and consensus is a critical failure that must be corrected with new studies.

The worst case scenario is that humankind faces an extreme climate emergency, but knows nothing about even the long-shot ways to address it. This is why scientists are asking now for a major investment in solar geoengineering research.

Photo credit: Keutsch Group at Harvard
Photo credit: Keutsch Group at Harvard

The researchers behind the forthcoming Harvard project, the Stratospheric Controlled Perturbation Experiment (SCoPEx), say we must study solar geoengineering in case we need to take a drastic action against climate change. The Gates-supported study seeks to do exploratory, small-scale experiments in the atmosphere:

“We plan to use a high-altitude balloon to lift an instrument package approximately 20 km into the atmosphere. Once it is in place, a very small amount of material (100 g to 2 kg) will be released to create a perturbed air mass roughly one kilometre long and one hundred meters in diameter. We will then use the same balloon to measure resulting changes in the perturbed air mass including changes in aerosol density, atmospheric chemistry, and light scattering. [W]e plan to release calcium carbonate, a common mineral dust. We may also release other materials such as sulfates in response to evolving scientific interests.”

What Happens Next?

Calcium carbonate is a plentiful and harmless mineral that’s also the active ingredient in Tums. But “harmless” only goes so far – the repercussions of solar geoengineering aren’t necessarily found in the material released, but in the unexpected effects of mixing ingredients into the stratosphere. This is why, SCoPEx says, most research has focused on an aerosol chemical already found in the stratosphere: sulfuric acid, which is a pollutant. Both need to be studied, and likely more.

Meanwhile, for a new prepublication report, the NASEM convened a committee of 16 international science luminaries to develop solar geoengineering research. Researcher Chris Field writes:

“Globally, 2015-2019 were the 5 warmest years in the instrumental record. The creation of this study committee is one response to the need for understanding the full range of options for dealing with the climate crisis.”

Chapters in the report include the role of philanthropists like Gates, the goals of preparing future political decisionmakers, and the state of existing research about solar geoengineering.

So, is all of this a good idea or not? That’s hard to say right now, but all of the scientists and backers involved are only suggesting doing research – not taking large-scale action.

No one is suggesting we spray the clouds with calcium carbonate tomorrow, or even 10 years from now. But if we don’t understand how solar geoengineering will affect the world, by the time we need it as an option in our climate playbook, it will be too late. And that’s what this news really is: keeping options open and exploring the ramifications of a radical technology.

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