Injecting sulfur dioxide (SO2) particles into the stratosphere to make them reflect sunlight is one of the old dreams of geoengineering, a measure considered as a last resort if the rise in temperatures cannot be stopped by reducing greenhouse gas emissions.
The strategy is inspired by a phenomenon that sometimes occurs naturally, when large volcanic eruptions transport so many of these aerosols to the upper part of the atmosphere that they produce a temporary cooling of a few tenths of a degree. And it has been studied by rigorous institutions such as Harvard University, although their project to study this possibility (SCoPEX) was recently canceled.
Now, a South Dakota (USA) based company called Make Sunsets (Making sunsets) became the first company to offer this geoengineering strategy to individuals. For just over a year, officials have been selling their customers “cooling credits” equivalent to the release of one gram of SO2 at altitude.
“Offset one ton of CO2 per year with just 9.95 euros,” they announce. The transport is carried out using helium balloons that rise to an altitude of more than 20,000 meters and release small amounts of sulfur dioxide into these remote regions of the sky in order to reflect some of the sunlight and help lower the temperature.
A “cloud” to calm consciences?
According to the creators, each gram of these aerosols offsets the warming of one ton of carbon dioxide released by burning fossil fuels. Since February 2023, they have released 53 kilos of these aerosols and boast that this is equivalent in terms of cooling to planting 2.5 million trees. “The balloons release tiny particles into the stratosphere, creating a thin reflective layer that reduces the amount of heat reaching the Earth’s surface and prevents the planet from overheating,” they write. And they appeal to the conscience of those who wish to offset the emissions produced by their daily activities.
The name of the company (Making sunsets) refers to one of the most striking consequences of the stratospheric injection of these aerosols, which led to the discovery of this phenomenon at the end of the 19th century. In 1883, after the eruption of the Krakatoa volcano, correspondents from all over the world informed scientists of a series of spectacular sunsets recorded in different regions of the planet. This allowed them to understand the large amount of matter that the explosion had put into circulation in the atmosphere and was decisive for the beginning of the study of the role of aerosols in the Earth’s radiative balance.
The people behind Make Sunsets are playing with this romantic idea of creating a cloud in the stratosphere, a cloud that can be briefly seen in videos of the ascent of stratospheric balloons: when it explodes, the small amount of carbon dioxide remains suspended for a few moments in the sulfur that they have previously placed inside.
“We deployed our reflective clouds more than 20 kilometers above the Earth’s surface using balloons,” they write. “They stay up for about a year, reflecting some of the sun’s rays as well as the natural clouds below. Think of it like using sunscreen spray to protect your skin from the sun.”
However, many atmospheric science experts question this strategy, as well as its safety.
“A ridiculous amount”
“Technically yes, if you put these particles in the stratosphere you prevent some of the radiation from reaching,” admits Francisco J. Tapiador, professor of Earth physics at the University of Castilla-La Mancha (UCLM), to elDiario.es. “The problem is that these amounts have a very small effect and we are dealing instead with a company that offers to clear its conscience by paying a few dollars.” According to him, initiatives like this are “atrocious”, especially because they jeopardize serious and collective efforts in the field of geoengineering, such as those reported in the report. An atmosphere (An atmosphere), under the auspices of the UN, which defends international governance of the stratosphere. “They will create bad press for initiatives that we may have to use at some point, even if governments will have to do it.”
They will create bad press for initiatives that we may have to use at some point, even if governments will have to do so.
Francisco J. Tapiador
— Professor of Earth Physics at the University of Castilla-La Mancha (UCLM)
“We know that if you load the atmosphere with aerosols of this type, solar insolation is reduced,” he says. Luis Banonspokesman for the State Meteorological Agency (AEMET). “Another thing is how effective it can be to put a kilogram of aerosols in a balloon and raise it to an altitude of 20 km.” According to him, these types of companies are taking advantage of legal loopholes and have seen a market opportunity to offer a product. “The philosophy of this company is ‘do it and then ask for permission’, although in Europe I don’t think they could do something like that.”
Another aspect that experts focus on is the limited scope that the emission of 50 kilos of aerosols into the stratosphere can have in the face of a global problem such as global warming. “Any emission from a medium-sized volcano has a much greater impact; it is more of a gesture or a deal than anything else,” Bañón explains. “It is a ridiculous amount,” he adds. Jose Luis SanchezProfessor of Applied Physics at the University of León. “To give you an idea, a coal-fired power plant emits several tons of SO2 every hour.”
Huge uncertainty
In any case, no matter how small the amounts of aerosols are, there is still great uncertainty about how these particles will act and interfere with other processes, Sánchez warns. “We don’t know how they will behave in the future, so everything you do is confusing.” The main problem is that the material that is deposited in the stratosphere stays there for a long time, since there is no precipitation, and when it is very massive – as in the case of eruptions – it circles the globe.
I am very afraid that this sulfur dioxide will interfere with other natural processes such as the formation of ozone.
Jose Luis Sanchez
— Professor of Applied Physics at the University of León
“I am very afraid that this sulfur dioxide will interfere with other natural processes such as the formation of ozone,” the expert explains. “It The ozone hole in Antarctica occurs because the ozone creation processes are altered during the winter, because the sun does not arrive, a situation very similar to what they want to create with these clouds. “It seems to me totally unfortunate to bet on a possible technology with a huge amount of uncertainty.”
“We don’t know the possible adverse effects,” adds Tapiador. “In the stratosphere there are many processes that we barely know about, playing sorcerer’s apprentice by injecting aerosols is very dangerous, things can happen that we don’t know about because it has never been done, such as a chain reaction at the atmospheric level that modifies the temperature regime of the rains or the configuration of the winds in certain places. On the other hand, warns Sánchez, other aspects must be taken into account, such as the fact that helium production is expensive in terms of CO2 emissions. “It is very difficult to determine the total balance between what you intend to do to prevent the entry of solar radiation and the effect that the whole process has,” he says.
The perverse logic of the market
To Jon Sampedro, researcher at Basque Center for Climate Change (BC3) and an expert in energy transition, is concerned that the proliferation of this individual approach sends the wrong message about how to effectively combat global warming. “If we already know what a risk-free energy transition model is, a shift to renewables that reduces energy consumption and emissions, why are we going to enter these levels of uncertainty?
Sampedro also believes that promoting these compensation pathways follows a perverse logic and can discourage efforts to reduce emissions. “This can prevent companies that want to compensate in this way from reducing their emissions sufficiently,” he stresses. “These solutions cannot be an excuse for not doing one’s homework.”
It can be used to ensure that those who wish to offset in this way do not reduce their emissions. These solutions cannot be an excuse for not doing your homework.
Jon Sampedro
— BC3 researcher and energy transition expert
For Francisco Tapiador, the problem could arise especially if this model proliferates in other large, less regulated countries like China, Brazil or Argentina. “Ultimately, it’s an example of the entrepreneurial spirit of the United States,” he sums up. “You create a market for emissions and people look for ways to benefit from it and take advantage of the interest of many people to mitigate climate change to the extent that they can,” he emphasizes. And it’s also a way to continue to contaminate with a clear conscience. “The problem is that we have built a society whose well-being is based on cheap oil,” he concludes. “Changing all that is going to be very complicated.”
