Low Energy Fridays: Should we block the sun’s rays to fight climate change?

People have many ideas for addressing climate change. Proposed solutions range from the basic (plant a tree, or maybe a trillion of them) to the technocratic (revenue-neutral carbon tax) to the insipid (throw paint on Stonehenge). Some ideas, though, are so creative as to be almost out of this world. 

Among the latter type is Make Sunsets, a company that aims to offset the effects of global warming by blocking some of the sun’s rays before they reach Earth. We have known for a while that certain aerosol substances, such as sulfur dioxide (SO₂), reflect sunlight when present in the upper atmosphere. In high enough concentrations, these aerosols can substantially reduce global temperatures. In 1991, the eruption of Mount Pinatubo sent 17 megatons of SO₂ into the stratosphere, resulting in around a half-degree reduction in average temperatures in the Northern Hemisphere over the next several years. 

Encouraging volcanic eruptions is not exactly practical, so instead, Make Sunsets fills balloons with a mix of SO₂ and helium and releases them into the air—like children at the end of a birthday picnic. When the balloons get high enough, they pop and disperse SO₂ into the atmosphere, creating a slight cooling effect. 

For the price of $10, Make Sunsets will fill a balloon with enough SO₂ to offset one ton of carbon dioxide (CO₂) for one year. One balloon might not sound like much, but they’re large, and it doesn’t take much to offset a ton of CO₂. So far, the company claims to have launched 78 balloons, offsetting around 50,000 tons of CO₂. We don’t know yet what measurable effect this has had.

This process is one example of a larger suite of ideas known as “geoengineering.” Instead of dealing with climate change by reducing greenhouse gas (GHG) emissions (known as mitigation) or by adjusting to the effects of a warmer world (known as adaptation), geoengineering tries to counteract the effects of greenhouse gas emissions directly.   

For years, I’ve quoted Larry King’s supposed quip that “the great outdoors would be nicer if it was half lit and air conditioned.” Unfortunately, my attempts to track down the source of this witticism only return quotes for outside air conditioning units, so I can’t be sure if he actually said it. In any event, each time I live through another Texas summer, I can see the appeal of installing a thermostat for the planet. 

On the other hand, attempts to control the planet’s temperature can raise some thorny ethical and political issues. Even within a home or workplace, people often have very different ideas about what the temperature should be. Imagine such disputes playing out on a global scale between nations—some of whom have nuclear weapons. 

Trying to fine tune the climate can also have unintended consequences, particularly since we have only a rough idea of how big a cooling effect comes from adding a given amount of SO₂ into the atmosphere. Some have suggested that large-scale geoengineering could affect weather patterns in unforeseen ways, such as by altering the Indian monsoons that the country relies on for food production. 

Additionally, aerosols like SO₂ don’t stay in the atmosphere for nearly as long as GHGs like CO₂. That’s good on one level, as it means such efforts are less likely to have long-term negative effects. But it also means we could get stuck continually adding more and more aerosols each year to deal with the longer-lasting effects from GHG emissions. 

Despite all this, we should expect such ideas to become a bigger part of the conversation around climate change in the coming years. This kind of geoengineering is cheap enough that even a small nation or rich billionaire could theoretically fund an amount sufficient to offset all recent emissions. And it’s hard to stop people from releasing balloons into the sky. So while efforts like this may not be the final answer when it comes to addressing climate change, it’s a subject we should all keep an eye on.