July 24th, 2020 by Steve Hanley
When Mount Pinatubo erupted in June of 1991, it shot 20 million tons of sulfur dioxide 22 miles into the atmosphere. As the gas spread around the world, it cooled the Earth by about half a degree Celsius. Now two Harvard professors say they are planning to inject calcium carbonate dust into the air over Arizona to see what effect it has on the amount of solar radiation reaching the Earth below. The dust “would reflect away a little bit of sunlight, just the way a very thin cloud reflects away a little bit of sunlight … to offset some of the warming that comes from the slow buildup of carbon dioxide from our industrial activity, David Keith, a professor of applied physics at Harvard, tells WBUR.
Mt. Pinatubo eruption, image credit: USGS
Keith is working with Frank Keutsch, a professor of atmospheric chemistry, to determine what the effect of that rock dust might be. Together, they have created a laboratory experiment that involves a metal tube about a yard long and a few inches wide. Inside, they have recreated the gaseous composition of the stratosphere, the atmospheric layer above the troposphere that begins between 10 and 10 kilometers above the Earth.
“So we go to stratospheric temperatures. We go to stratosphere pressures in there,” Keutsch explains. “We put in the aerosol that we want to understand the reactivity of. And then we look at these reactions [in the tube].”
Calcium carbonate is plentiful and cheap. It is the primary component of limestone and the shells of aquatic animals found in the world’s oceans. It is non-toxic and is used commercially in common household products such as toothpaste and antacids. There is none currently found in the atmosphere. One of the objectives of the research in the lab is to determine if the calcium carbonate would have a negative effect on ozone levels.
The plan is to load about 2 kilograms of calcium carbonate aboard a standard scientific balloon and launch somewhere in the American Southwest. “The balloon is about a few stories in diameter, and these are the same as other stratospheric balloons that have been used for science for a long time,” Keith says. The balloon would carry the calcium carbonate to an altitude of about 12 miles above the Earth. Beneath the balloon would be a metal gondola equipped with propellers.
“That gondola has a mechanism that allows you to inject particles into the stratosphere,” Keutsch says. “So as you’re moving along, you make a plume that is about a kilometer, few kilometers in length. Then you would try to turn the balloon around and sample back going through this plume, comparing how the air outside of the plume is different from the air and the aerosol in the plume.” Their project is called SCoPEx — short for Stratospheric Controlled Perturbation Experiment.
The Case For Geoengineering
The experiment is part of a process known as geoengineering, an array of strategies for humans to avoid the most catastrophic effects of human activity over the past 250 years. For some, it is the “magic bullet” that will allow us to “science our way” out of the impending climate disaster. Find a way — any way — to block some of the sun’s energy that bombards the Earth every day and deflect part of it back into space. It’s not that different from what people used to do to cool their homes in the days before air conditioning — deploy awnings over the windows and pull the curtains inside the house. It worked amazingly well, as I recall.
Scientists have devised lots of theories about how to use geoengineering. Researchers in Norway advocate injecting air bubbles into the oceans to lower the temperature of surface water. Hurricanes need hot surface water to form. Cooler water equals less powerful storms, or none at all in the best case scenario. Others propose using rockets to inject sulfur dioxide — the same gas that spewed forth from Mt. Pinatubo — to block some of the sun’s rays.
If it works, all the happy humans will be able to carry on doing exactly what they have been doing for centuries — burning fossil fuels to power civilization — and nothing has to change. As Steely Dan would say, “What a beautiful world this will be. What a glorious time to be free.”
The Case Against Geo-Engineering
Lots of people are not so sure geoengineering is that answer, and believe it could create more problems than it solves. The essence of this argument is that the Earth’s atmosphere is fantastically complex. A small change over here could have massive consequences over there, perhaps condemning part of the world to punishing floods or extended droughts. As Michael Barnard said last year, “It’s like putting out the fires caused by an arsonist wandering around with a flamethrower.”
The real solution is to stop burning fossil fuels, a strategy that few are willing to consider for fear that it might interrupt the comfortable lifestyles we have become accustomed to. The latest climate research reveals some of the complexity of climate science and suggests the dream of keeping average global temperatures from increasing by more than 1.5° C is no longer a realistic possibility.
Daniel Cziczo is the head of the department of earth, atmospheric and planetary sciences at Purdue University. For a decade before moving to Purdue, he taught at MIT. He says mucking about with the atmosphere is incredibly dangerous. “As soon as you start putting particles into the stratosphere, aren’t you intervening with climate?” he asks of WBRU.
He says the SCoPEx project fits into a category he calls “climate intervention” instead of solar geoengineering, and he says the science is dangerous. “Even though you’re saying, ‘I’m doing it as an experiment,’ the result is exactly the same,” he says. “It might be a smaller scale … But I would argue that if you’re putting enough material there that you’re going to be looking at the properties of that material and trying to tell what effect they have, that what you’re doing is an experiment on climate intervention.”
Cziczo says full-scale climate intervention would disrupt the formation of clouds, further hurt the ozone layer, and do nothing to reduce carbon in the atmosphere. “I’m not willing to sign up for something that’s a solution to the [earth’s] temperature problem that’s going to cause more skin cancer, that’s going to allow for continued acidification of the oceans, or that’s going to cause regional droughts or precipitation,” he says. “I’m just not personally comfortable with that, especially when we have another path in climate, which is the reduction of these greenhouse gases that we know are the underlying cause.”
An Agreement In Principle
The three scientists agree the real solution to global warming is to cut back on fossil fuels. They’re concerned people will view solar geoenginering as an easy out and refer to what they call the “moral hazard” of the science. “This experiment can be misinterpreted as that there is a technical remedy that gets us off the hook, where it should be clear that … even in the best case scenario with the solar geoengineering in the stratosphere, it doesn’t address the causes of climate change,” Keutsch explains. “It’s addressing a symptom.”
David Keith is concerned about the energy industry shirking its responsibility in helping reduce global warming. “I’m talking about big oil, big fossil fuel companies — that they will claim that because of this techno fix, there’s no need to cut emissions. That’s not true. Nothing about solar geoengineering changes the fact that if you want a stable climate, you eventually have to cut emissions to zero.” (emphasis added)
We Need Research AND Carbon Reductions
“The combination of emissions cuts and solar geoengineering could actually be significantly safer, have lower human and environmental risks, less sea level rise, less people dying from heatstroke, less change in the high arctic glaciers than would a world with just emissions cuts,” Keith says. “So there’s really a prize here, a huge human and environmental benefit.”
But the scientific community needs to research the consequences — good and bad — before world leaders make rash decisions, the researchers say. “Some government faced by maybe a huge killing heat wave may make decisions to actually move forward deploying these technologies within the next decades, whatever research we do,” Keith says. “We are more likely to make a reasoned decision as a species, as humanity, about this if we get it out in the open, warts and all.”
No International Geoengineering Standards
There is no national or international governing structure for solar geoengineering. What Keith and Keutsch are planning to do could be subject to review by the US government under national laws regulating environmental policy and weather modification. The ethical questions raised by their research has prompted Harvard to form an independent committee to review and make recommendations on all aspects of the experiment, including its safety and environmental impact.
Despite the ethical concerns, Keith and Keutsch are planning to move forward with their experiments on the theory that some knowledge is better than no knowledge. At least they are using non-toxic calcium carbonate instead of sulfur dioxide, which forms harmful compounds like sulfuric acid when it mixes with water.
Perhaps someday, the team will be hailed as leaders of a scientific revolution that saves humanity from extinction. Or their research could lead to unintended consequences — like the infestation of rabbits in Australia that resulted when one wealthy sportsman wanted something to hunt and had them imported for his amusement. We should always keep in mind that it’s not nice to fool Mother Nature!