And in this race, every idea is worthy of study, even if it is the most audacious: cooling the Earth by reducing the solar radiation that passes through the atmosphere on a planetary scale.

Geoengineering against climate change has been present on experts' boards for decades. In its most basic form it seeks to eliminate greenhouse gases from the Earth's atmosphere, for example by sequestering CO2 inside the Earth. However, a second variant pursues a more ambitious objective, shielding solar radiation to compensate for global warming; something like placing an umbrella over the planet.

The solution that has attracted the most interest in recent years is the dispersion of sulfate aerosols, a process that aims to mimic the effect of large volcanic eruptions.

Obviously, such a radical proposal requires extensive and in-depth studies to ensure that artificial climate modification does not in itself engender disastrous consequences. For this reason, climate engineering has been a controversial discipline since its birth. Although numerous experts agree in defending geoengineering research, there are still serious doubts regarding the approaches that deserve more detailed study.

The most concrete idea that is being used today consists of dispersing aerosols of particles in the atmosphere to reduce the insolation of the Earth's surface. Regarding the nature of such particles, various proposals have been put forward, such as microdroplets of seawater, ice crystals or even alumina and diamond dust.

The solution that has attracted the most interest in recent years is the dispersion of sulfate aerosols, a process that aims to mimic the effect of large volcanic eruptions.

Side effects

However, the proposal raises serious concerns. Experts suggest the procedure could dangerously alter global rainfall patterns and damage the ozone layer due to the sulfuric acid formed. In 2018, a study published in Nature analyzed natural experiments from past volcanic eruptions to determine their effects on agriculture. And while a reduction in warming alleviates heat stress in crops, the results showed that decreased sunlight negatively affects growth.

In 2023, another modeling study discovered that the effects of a possible dispersion of aerosols in the atmosphere on corn, rice, soybean and wheat crops would vary in different areas of the world: an intense intervention would favor production in the equatorial region, while A more moderate one would be more advantageous for mid-latitudes and, on the other hand, the countries further away from the Equator would benefit from climate change without this brake. That is to say, there is no optimal “one size fits all” for the entire planet.

In 2023, another modeling study discovered that the effects of a possible dispersion of aerosols in the atmosphere on corn, rice, soybeans and wheat crops would vary in different areas of the world.

From computer models to the real world

Particles of a material that does not damage the ozone layer will be used: calcium carbonate, the same that forms limestone rock, shells and eggshells, and which is also used as a digestive antacid. Instruments located on the balloon will measure changes in atmospheric chemistry and the scattering of sunlight.

Halving the temperature rise due to greenhouse gases would prevent drastic changes in temperatures and precipitation.

Among the proposals, the spraying of seawater with cannons to form whiter, denser clouds that protect corals from excessive warming of the water is being tested on a small scale in Australia's Great Barrier Reef.