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The idea was once taboo, but desperate times may simply call for desperate measures.
If humans are able to spray millions of tons of sulfate aerosol into the sky, we could create a kind of chemical awning that reflects the heat of the sun and mitigates global warming.
This type of atmospheric piracy could be dangerous, but as catastrophic climate change increases its hold on the planet, Harvard researchers are beginning to take the idea of solar geoengineering more seriously.
"The fact that researchers from one of the world's largest universities are paying such a radical program deployment shows the urgency of the climate change problem," said Peter Cox, expert in dynamics. of climate at the University of Exeter. The Guardian.
To date, the most detailed analysis of such a system has revealed that, although the aerosol injection is very uncertain and ambitious, it is "technically possible" from the point of view of view of engineering.
It would also be "remarkably inexpensive" to finance. With the help of a fleet of aircraft specifically designed to periodically pulverize sulfate particles in the lower stratosphere, Harvard's research suggests that we might be able to cool the planet at a price largely within reach of several countries.
If the program were launched in 2018, the authors predict that it would cost about $ 3.5 billion, to which an additional $ 2.25 billion would be added per year for program maintenance. To put this into perspective, the world is currently spending about $ 500 billion a year on green technologies – an investment of much greater magnitude.
"Dozens of countries would have both the expertise and the money to launch such a program," the researchers conclude.
"About 50 countries have military budgets over $ 3 billion and 30 to over $ 6 billion."
To achieve this radical plan, one of the heaviest expenditures would be to create a new fleet of streamlined aeronautical jets.
The only inexpensive and reasonable option for the distribution of aerosol is the plane. But an airplane that can travel 20 km high while carrying a huge aerosol payload? Nothing like it currently exists. And we have to do it if we want the sulphate particles to stay in the atmosphere for over a year.
For this reason, the researchers designed an entirely new aircraft, featuring a narrow body and large wings, as well as two additional engines.
Starting with a fleet of only eight jets – and ultimately ending up with nearly 100 aircraft – a sulphate injection program would achieve more than 60,000 missions per year in just 15 years.
However, if this technology can help mask some of the symptoms of climate change, it will not solve the problem completely, which will only worsen ocean acidification and other consequences. Moreover, none of this affects the uncertainties and risks associated with deploying such a plan.
Although solar geoengineering is often described as "fast, inexpensive, and imperfect," the Harvard study supports only the first two claims. Today, the imperfections of this technology remain unclear and potentially very dangerous.
Pumping enough sulphate into the atmosphere to mimic a volcanic eruption is a risky activity. It is also one of those solutions that, once launched, can not be stopped.
If the program ends for any reason, scientists believe that the rate of global warming would likely come back with a vengeance, rapidly increasing global temperatures and leaving less time for human society and ecosystems to adapt. .
As a solution to climate change, some scientists have compared the fact of throwing a bear into the arena with a lion: "You know, maybe they'll fight and kill each other. They will kill you both. "
Some experts even went so far as to call solar geoengineering a threat to democracy. After all, what will happen if a country takes over global climate through solar geoengineering? What if they do it without the consent of the rest of the world?
In this regard, the Harvard study offers a comforting thought. The results suggest that an aerosol injection program would require an activity so extensive that it would be almost impossible to keep it secret from the rest of the world.
"No comprehensive program of SAIs of the magnitude and nature discussed here could reasonably be expected to maintain secrecy," Smith said.
"Even our deployment program hypothesis for the first year involves 4,000 plane flights the size of an airliner at unusually high altitudes in several flight corridors of both hemispheres.This activity is much too important to remain undetected. "
Until perhaps, one day, we decide that the risk is worth it.
This study was published in Letters of research on the environment.
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