Artificial ‘Sun Blocking’ As Solution Against Global Warming; What Are the Risks of Dimming Solar Light?

It has become apparent that we might fail to meet our climate goals since we are already at 1.26 degrees Celsius of warming in 2022 and will blow through 1.5 degrees Celsius by the mid-2030s. Studies have also shown that the current climate policy will lead to over 2.5 degrees Celsius of warming by the end of this century.

Global warming at this scale has the potential to destroy vulnerable communities and ecosystems around the world. For this reason, experts and policymakers are considering radical new solutions that can stop climate change.

Solar Radiation Management

Powerful volcanic eruptions, such as Tambora (Indonesia) in 1815 and Pinatubo (Philippines) in 1991, dropped global temperatures for a few years. Major volcanic activities create a hazy layer of microscopic particles in the Earth's upper atmosphere. Since they last for several years, the Sun gets dimmed temporarily. This has become an inspiration for scientists in developing solutions against climate change.

Our planet is warmed by the Sun, but it is kept warm by greenhouse gases that trap the Earth's heat. The warming effect of our carbon dioxide emissions can be reversed by creating an artificial, persistent haze like those of significant volcanic eruptions. Studies have shown that we only need to dim the Sun by around 1% to cool the Earth by one degree Celsius.

Assessment of solar geoengineering suggests that it would be feasible and cheap to do this by using a fleet of high-flying jets to release reflective particles in the upper layer of the atmosphere. Still, dimming the Sun will not reverse climate change perfectly. The Sun's warming effect is strongest during the day, in the summer season, and in the tropical region, whereas greenhouse gases warm the entire planet at all times.

To address this concern, experts suggest creating an even cooling effect by adjusting where the particles are released. It is believed that such an approach will greatly reduce the risks of global warming.

Blocking some solar light would also be an effective way to keep icy parts of the Earth frozen. The melting of Antarctic and Greenland ice sheets due to rising temperatures drives the global sea level. Climate change also thaws permafrost, which can lead to more carbon dioxide and methane emissions.

Is It Safe to Dim the Sun?

Dimming the Sun may keep the Earth cool, but it will not deal with the root cause of global warming: the buildup of greenhouse gases in the atmosphere. Carbon dioxide raises global temperatures and acidifies the ocean, making it more challenging for corals and other marine creatures to build shells. These events will not be changed by the proposed blocking of the Sun.

This approach will likely bring other side effects as well. The hazy layer of particles will make the sky a little whiter. If we will also imitate volcanic eruptions by releasing sulfate particles into the upper atmosphere, it will only add to the problems of acid rain. The ozone layer may also be affected by these particles. Research shows that adding sulfate particles to the atmosphere will delay the slow recovery of the ozone hole.