Turning off the shower a little sooner than you’d like to, dialing back the central heating, or ordering a vegetarian dish instead of that steak you’d rather eat: most people make an effort to help stave off the disastrous effects of a warming climate in some way or other. But did you know there’s a group of scientists considering the possibility of covering the Arctic in numerous tiny glass balls? Or sending iceberg-producing submarines that way? Or even to artificially make clouds appear whiter? Well, there is. And all these projects can be considered as a form of geoengineering.
What is geoengineering?
According to the Harvard’s Solar Geoengineering Research Program, “geoengineering refers to a set of emerging technologies that could manipulate the environment and partially offset some of the impacts of climate change”. Geoengineering can roughly be divided into two main categories: carbon geoengineering, or carbon dioxide removal (CDR) and solar geoengineering, also called solar radiation management (SRM). This article will mainly focus on the latter.
Whereas carbon geoengineering is aimed at removing the carbon dioxide from the atmosphere and therefore tackles the root cause of climate change, solar geoengineering is focused at reflecting some of the sunlight back into space and thus doesn’t address the fact that there are too many greenhouse gasses in the atmosphere. Neither goes into the real driver of the climate crisis, which is the emission of those greenhouse gasses.

Reflecting heat
Broadly speaking, SRM is aimed at reflecting sunlight back into space, thereby preventing the sun’s rays from heating up our globe further. Think of the reflective screens people put behind their car’s windscreen to keep the heat out on a smoldering day: it’s a bit like that, but on a much bigger scale. Some cities opt for painting the roofs of their buildings with a reflective paint to combat the heat-island effect (cities tend to get much hotter than less urbanized spaces due to the lack of greenery and wind). But a lot of the SRM efforts are aimed at reflecting the sun’s heat on a very specific place though: the Arctic.
The problem with the Arctic heating up, is that the white ice already reflects a lot of heat back into space - should that ice melt, the water underneath would be revealed. And if you’ve ever seen a picture from the earth from outer space, you know that water appears very dark. The darker the surface, the more heat it absorbs instead of reflects, resulting in a higher temperature. Basically, the hotter it gets, the more ice melts, the sooner it becomes even hotter. Kind of a snowball-effect, ironically.

Small parts, big impact
So, enhancing the reflectiveness of clouds or the earth’s surface is one type of SRM, also called albedo enhancement. Then there’s the idea of space reflectors (yes, really), to reflect sunlight before it even reaches the earth. Another option is that of stratospheric aerosols: putting small, reflective particles in the atmosphere.
A popular candidate for such particles is sulphur dioxide, which is controversial because of its potential health and environmental risks. Moreover, in theory the particles would be used solely in the polar areas, and they would also settle there. However, in practice, there is no guarantee of what will happen with those particles. Plus, they would likely be introduced via aircraft, which in itself would emit even more greenhouse gasses. Yet it might also lead to lower temperatures on the poles, slowing down the thawing of the ice. For a more in-depth explanation, see this article by the Guardian.
Salty clouds
In the same article, the concept of cloud brightening is discussed: making clouds appear whiter, and thus more reflective. This practice eliminates the need for sulphur dioxide, as all that is sprayed into the air is the salty water itself. Like the water in the ocean, the clouds formed over them are salty. Salt crystals come in a variety of sizes, and the smaller the crystal, the smaller the drops of water in the cloud are. So by spraying salt water into already existing clouds, those clouds are better equipped to reflect sunbeams.

Pros & cons
To recap: on the plus side, SRM could slow down the melting of Arctic ice and in that way slow down the adverse effects of climate change significantly. On the downside, SRM doesn’t address the actual source of the problem of the climate crisis at all, and merely acts as a plaster on the wound that is created by greenhouse gas emissions. But the pros and cons of geoengineering go much further and are far more complex than just these two arguments.
For one, the application of SRM could alter weather patterns and consequently, impact crop yields. Meaning, SRM could have serious implications for the world’s food supply. Secondly, although locally the situation could be improved, other areas of the world could suffer all the more since we simply don’t have a clear idea of what the full range of effects of SRM would be.
Widening the gap
“There’s no way to even imagine deploying it on a global scale so that everybody would benefit”, says Jennie Stephens, a professor of sustainability science and policy at Northeastern University, to MIT Technology Review. “Some people would be screwed, and some people may have reduced suffering. So it’s creating one more mechanism by which to interfere with the Earth systems and then privilege some and disadvantage others”. In other words, it has the potential to widen the gap between the rich and poor even further.
Moreover, there is a risk that if these technologies are developed, it would enable individual (wealthy) countries to employ them in a way that affects the entire planet. One nation attempting to combat their increasingly frequent heatwaves and wildfires could dupe another into having more climate-related struggles. There is also a chance that the mere availability of these technologies would make governments quicker to point the finger in the case of impactful weather changes. This could even go so far as to spark conflicts.
Should we globally pursue geoengineering? Please share your thoughts in the comments!
A deep hole
Clearly, there are ample potential negative effects from SRM. But global warming is showing little signs of slowing down, with 2023 even being the hottest year on record. In theory, it might seem simpler to cut emissions, but in practice this is clearly not true. Geoengineering is seen as a solution despite all its downsides, simply because it seems to be the best option we’ve got. “It is not one’s first choice for dealing with global warming”, says Andy Parker, chief executive officer of Degrees, a fund that gives small grants to scientists from the global south to explore the possible effects of solar geoengineering on their climate, to the Financial Times. “It is a recognition of how deep a hole we are in.”
As Rachel Riederer writes in her article for The New Yorker:
“No amount of glass spheres or roofing granules will reverse climate change. Only a rapid global shift away from fossil fuels is likely to achieve that. But in a place like the Arctic, which is warming four times faster than the rest of the planet, and where the end-of-ice tipping point hangs like the Sword of Damocles, such an intervention could offer a precious lifeline: time.”
Does the end justify the means regarding geoengineering? The jury’s still out. But it seems like we will very soon find out, since tests have already begun and will likely only become more frequent.
I think it’s important that we do research on these technologies because they might be our best way to somewhat limit the bad consequences of climate change. However, it should not distract us from the primary concern, limiting CO2 emissions.