Silicon Valley startup’s rogue effort to cool planet met with controversy

High up in the hills near Silicon Valley, a controversial mission involving a weather balloon will soon take flight.
Inside a trailer on a blistering hot day, Luke Iseman and Andrew Song are busy preparing the instrumentation to attach to the balloon. Iseman and Song are the co-founders of a startup called Make Sunsets.
Song then went outside and unfurled a balloon and began to fill it up from two gas canisters.
“Go ahead and start it slowly,” instructed Iseman.
What’s getting pumped inside the expanding latex balloon are sulfur dioxide and helium.
When the high-altitude balloon is properly filled with the correct mix, Song released it. The helium will carry it more than 12 miles above the surface of the earth into the stratosphere. Once there, the balloon bursts, releasing the sulfur dioxide.
The belief: that the gas turns into an aerosol, which will bounce the sunlight back into space, cooling the planet.
“That gas reacts with other things to form clouds that reflect a little bit of sunlight back into space before it can warm Earth,” said Iseman.
The strategy is a form of solar geoengineering called Stratospheric Aerosol Injection or SAI for short. It seeks to temporarily cool the planet, as human activities continue to warm it, by burning fossil fuels. 
“Much of the world is barreling ahead, drilling baby drilling. We need innovation for solutions as well because the problem is getting worse,” explained Iseman.
Reducing greenhouse gases is not occurring quickly enough and the current attempts may be insufficient to delay or reduce the changes of the most serious impacts from global warming. 
“Even if we magically can stop fossil fuels tomorrow, and somehow have some other magical energy to replace it, there will still be this warming built in,” explained Song.
The method that these two men are deploying may offer a way to buy time as scientists try to come up with better solutions to reduce the rising global temperatures.
Since 2022, Iseman and Song have launched than 80 balloons.   For each launch, they contact the FAA, and once a year, file paperwork with NOAA.
The concept behind the method is based on the planet cooling effects of volcanic eruptions. A good example is the massive 1991 eruption of Mount Pinatubo in the Philippines.
It injected 15 million tons of sulfur dioxide aerosols into the stratosphere, dropping temperatures around the world.
“Pinatubo actually cooled the earth by about three tenths of a degree Celsius or half a degree Fahrenheit for several years after the eruption,” said Dr. William Collins, Associate Laboratory Director of the Earth and Environmental Sciences Area at Lawerence Berkeley National Laboratory.
Collins is also a top expert on aerosols and climate change science.
“We know these aerosols can cool the climate. And the question that people are now asking is could we do that artificially,” the scientist told CBS News Bay Area.
Another pending question: what about the risks?
Make Sunsets is not alone in the endeavor to deploy solar geoengineering.
There are larger entities around the world who are also looking into using the technology. And that concerns other scientists.
“We don’t want to be going full bore ahead with a deployment at this stage. We don’t know what will happen,” remarked Dr. Lisa Dilling, an associate chief scientist with the Environmental Defense Fund.
The nonprofit is financing scientific research into artificial cooling technologies.
The goal: to identify and better understand any unknown risks or side effects.
“What we will be looking at is how to compare this to the risks of climate change itself,” Dilling added.
NOAA’s Climate Program Office is actively studying the technology as are various think tanks around the world, including the Kleinman center for Energy Policy at the University of Pennsylvania.
As for Iseman and Song, their endeavors are not illegal. They’re also selling cooling credits to companies and individuals to offset their carbon footprints.
The team is willing to share its data with scientists but is not willing to stop the launches.
“We can’t let concern about impacts be an excuse for inaction. Or we end up with more intense versions of all the problems that we already have,” concluded Iseman.