In times of record temperatures, scientists are continually evaluating innovative (and controversial) solutions related to geoengineering. The last one? Manipulate clouds to reflect more sunlight back into space. This strategy, called “marine cloud brightening” (MCB), could theoretically slow global warming. But before we can even consider putting it into practice, there is still a lot of work to do to understand its potential benefits and risks. A new study (that I link to you here) leads the way to filling these knowledge gaps.
Playing God with the clouds
The idea behind the MCB is as simple as it is bold: make sea clouds more reflective by spraying salt water into the air. Not from the sky, as in the case of the so-called "insemination” of the clouds (someone speaks openly of chemtrails, and it's not about conspiracy theorists). In the case of this study, no chemistry and no planes: the sea salt comes directly from the sea, and is sprayed from ships. In practice, it would involve creating a sort of natural "solar shield" to protect the Earth from the sun's rays. A bit like putting sunscreen on the planet, in short. Put it this way… In reality it is not simple, nor definitive.
The MCB does nothing to reduce the greenhouse gas emissions that are warming the planet. At most, it might give us a little extra time as we try to cut pollution. As he says Lynn Russell, co-author of the study, “we need to consider non-ideal backup plans just to buy enough time.” Already. Because there is very little that is "ideal" in this solution.
A road paved with unknowns
The idea of deliberately manipulating the Earth's climate is chilling to many. And with good reason: the effects of such a massive intervention on the delicate balance of our planet are still largely unknown. We could solve a problem by creating new ones and potentially worse.
Clouds, in fact, are a true climate enigma. Some block sunlight, others trap heat. The goal of the MCB, of course, is to have more clouds of this first type. But if we accidentally cause thinning clouds and rain, we could have the opposite effect and accelerate warming. In short, playing with clouds is like walking on a minefield.
To understand whether MCB can work in real life, researchers will first need to see positive results in laboratory tests and model studies. Then, they will need to test whether small field experiments can be scaled up to have a global impact. Satellite observations will be crucial for monitoring the outcomes of such experiments. But physical science is only part of the equation. There are also social and ethical implications to consider. How can we avoid disparities between those who benefit from this method and those who bear any unexpected burdens? The MCB could trigger changes in precipitation from region to region, for example.
A future in the clouds
In summary, the path towards a possible use of the MCB is still dark: but in a world that is literally cooking on a slow fire, perhaps we cannot afford to discard any option a priori, however extreme it may seem. So, dear scientists, please continue to explore the potential of MCB. But do it with the utmost caution and transparency. Because when it comes to manipulating the climate, we are literally playing with fire: and the last thing we need is another black cloud on the horizon.
