Artificial Sun Dimming, also known as solar radiation modification (SRM) or solar geoengineering, is a proposed set of technologies and methods aimed at reducing the amount of sunlight that reaches the Earth’s surface. The primary objective of artificial sun dimming is to counteract or mitigate the effects of global warming and climate change by reducing the amount of solar radiation that is absorbed by the Earth.
In Paris, former political leaders and heads of international organizations made a joint call on Thursday. They urged countries to temporarily stop using technologies to reduce global warming by lessening the Sun’s impact.
The Climate Overshoot Commission emphasized that research and experiments related to solar radiation modification (SRM) should continue. However, this should only happen under international supervision and in places where there are strong environmental safeguards.
At present, there is no established global authority overseeing the development or deployment of these technologies. Additionally, our understanding of the risks associated with them remains incomplete.
Commission member Laurence Tubiana, who leads the European Climate Foundation and played a key role in creating the Paris Agreement, stressed the need for a moratorium.
We are aware of the risks involved—this is not a magical solution. The failure to reduce the greenhouse gas emissions causing global warming has led to suggestions that solar geoengineering, once considered too risky a decade ago, could provide some time while we work on reducing emissions and removing CO2 from the atmosphere.
So far, the Earth has warmed by only about 1.2 degrees Celsius. However, even this modest increase has led to more frequent and severe heatwaves, droughts, and large storms that cause destruction and loss of life.
Paris Climate Agreement
The 2015 Paris climate agreement calls for limiting the rise in the Earth’s surface temperature to just 1.5 degrees Celsius above the levels of the mid-19th century. This is to prevent catastrophic consequences.
The commission gets its name from the high likelihood that the temperature will go beyond this target, known as an “overshoot,” probably within the next decade, according to the United Nations’ Intergovernmental Panel on Climate Change (IPCC).
In 2018, the IPCC determined that greenhouse gas emissions need to decrease by 43 percent by 2030 in order to keep global warming below the 1.5-degree Celsius limit. Methods for modifying solar radiation include making marine clouds brighter by adding salt particles from the ocean and positioning large mirrors in space to reflect sunlight away from Earth.
However, the technique with the highest potential, it is believed, involves injecting aerosols, particularly sulfur particles, into the stratosphere. This process helps reflect sunlight back into space.
Sometimes, nature itself employs a similar strategy. For example, during the violent eruption of Mount Pinatubo in the Philippines in 1991, millions of tons of dust and debris were released, which temporarily lowered global temperatures, especially in the Northern Hemisphere.
Yet, there is a growing body of evidence highlighting that while cooling the Earth’s surface may have advantages, it must be carefully considered alongside its unintended consequences.
Several studies have indicated that artificially reducing the Sun’s radiative force is likely to disrupt monsoon rains in South Asia and western Africa. Moreover, it could harm rain-fed crops that hundreds of millions of people rely on for food.
Additionally, this approach could potentially undo progress in the recovery of the ozone layer, which protects life on Earth from harmful ultraviolet radiation. This was outlined in the recent Scientific Assessment of Ozone Depletion report.
Furthermore, scientists caution that if we were to suddenly stop seeding the atmosphere with Sun-blocking particles, it could lead to a rapid increase in Earth’s surface temperature, a scenario known as the “termination shock.”