A subset of alarmists is convinced that to curb so-called global warming, they must block out the sun, at least partially. David Keith, founding faculty director at the University of Chicago's Climate Systems Engineering Initiative, is among them.

Keith, a multimillionaire who was previously at the University of Calgary and Harvard University, seeks to pollute the stratosphere ultimately with millions of tons of sulfur dioxide.

Blasting aerosols and other reflective substances, such as diamonds or aluminum dioxide, into the atmosphere, roughly 12-16 miles above the Earth, might replicate the effects of volcanic eruptions in blocking sunlight and lowering global mean temperatures.

The 1991 eruption of Mt. Pinatubo, which injected 20 million tons of sulfur dioxide into the stratosphere, resulted in a rapid half-degree drop in global temperatures. According to NASA, this drop lasted or two years until the sulfate dropped out of the atmosphere.

Without the guidance of Ivy League technocrats or the help of volcanoes, the species unwittingly found another way to lower global temperatures and scatter solar rays: using fossil fuels.

Emissions from cars, homes, and industry have long mixed in with low-altitude clouds, causing them to brighten and bounce more sunlight, resulting in a cooling effect. However, climate alarmists' ongoing campaign against the use of affordable energy — again, to supposedly curb global warming — might diminish this secondary benefit, thereby exacerbating global warming.

"I think most people are aware that there's a greenhouse gas effect that warms climate," Sarah Doherty of the University of Washington's Marine Cloud Brightening Program told the Weather Channel earlier this year.

"But what most people aren't aware of is that the particles that we've also been producing and adding to the atmosphere offset some of that climate warming," continued Doherty. "So, the overall effect is one of climate warming, but it would be a lot more without that particulate pollution."

Extra to reducing this low-hanging particulate pollution released by a productive society, Keith wants to release his alternative pollutant with a "purpose-built fleet of high-altitude aircraft."

In a February paper in the MIT Technology Review, he co-authored with Harvard Kennedy School research fellow Wake Smith, Keith noted that "offsetting a substantial fraction of global warming — say, 1 °C of cooling — would require platforms that could deliver several million metric tons per year of material to the stratosphere."

"Neither rockets nor balloons are suitable for hauling such a large mass to this high perch. Consequently, full-scale deployment would require a fleet of novel aircraft — a few hundred in order to achieve a 1 °C cooling target," said the paper. "Procuring just the first aircraft in the manner typical of large commercial or military aircraft development programs might take roughly a decade, and manufacturing the required fleet would take several years more."

While Keith acknowledged his scheme's current technological limits and cautioned against near-term deployment, he nevertheless advocated for policymakers to consider the possibility of deployment "earlier than is now widely assumed."

On the basis of his calculations, Keith, who made roughly $72 million off the sale of his carbon capture company to Occidental Petroleum, recently suggested to the New York Times that following through on his scheme would not only lower temperatures but might also change the hue of twilight.

Of course, orange twilight is far from the only possible side effect of such efforts to meddle with the sun and sky.

Numerous scientists have indicated that solar geoengineering might lead to humanitarian and ecological disasters.

In recent years, hundreds of scientists have signed an open letter calling for an international non-use agreement on solar engineering, stressing that "the risks of solar geoengineering are poorly understood and can never be fully known. Impacts will vary across regions, and there are uncertainties about the effects on weather patterns, agriculture, and the provision of basic needs of food and water."

Blaze News previously reported that a 2017 study published in Nature Communications indicated that aerosols released only in the northern hemisphere might increase droughts, hurricanes, and storms elsewhere.

"This is a really dangerous path to go down," Beatrice Rindevall, chairwoman of the Swedish Society for Nature, told the Times. "It could shock the climate system, could alter hydrological cycles and could exacerbate extreme weather and climate instability."

Oxford University atmospheric physicist Raymond Pierrehumbert has characterized solar geoengineering as a threat to mankind.

"It's not only a bad idea in terms of something that would never be safe to deploy," said Pierrehumbert. "But even doing research on it is not just a waste of money, but actively dangerous."

"There certainly are risks, and there certainly are uncertainties," Keith told the Times. "But there's really a lot of evidence that the risks are quantitatively small compared to the benefits, and the uncertainties just aren't that big."

While still a professor at Harvard, Keith attempted to run an experiment, possibly over Arizona. Unable to find a partner to launch a high-altitude balloon and met with objections by Indian groups and other critics, Harvard contracted the Swedish space corporation to run the test. That test was similarly met with controversy and aborted.

After his experiments were foiled, Keith pledged not to be "open in the same way" with future endeavors. He also left Harvard for the University of Chicago, which the Times indicated is permitting him to hire 10 new faculty members and kick off a new $100 million geoengineering program.

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