Dust of some minerals to cool the Earth

In a new study, the dispersion of diamond and calcite particles in the stratosphere has been explored as a tool to cool the Earth by increasing solar reflection.

The study was carried out by a team headed by Sandro Vattioni, from the Federal Polytechnic School of Zurich, and in which the Institute of Geosciences (IGEO), a joint center of the Complutense University of Madrid (UCM) and the Higher Council of Scientific Research (CSIC), in Spain.

The study explored the use of mineral dust as an additional measure to combat global climate change.

The results of the work suggest that injecting diamond and calcite particles into the stratosphere could help reflect the Sun’s rays back into space and thus reduce global warming. Experts warn that this strategy would not be a definitive solution to global climate change and highlight the need for further research to evaluate its economic viability and possible risks.

The study has combined climate modeling and laboratory measurements to examine how the optical properties of diamond and other minerals such as calcite (CaCO3) could be exploited as a climate intervention strategy to increase the reflection of solar radiation. Injecting aerosols into the stratosphere aims to replicate the effects of volcanic eruptions, which have been shown to temporarily cool the planet’s climate. The research team used a state-of-the-art climate model to simulate the effects of the injection and dispersion of ultrafine dust (150-300 nanometers) of different materials in the upper layers of the atmosphere. According to Gabriel Chiodo, IGEO scientist and co-author of the study, the climate model used is capable of simulating microphysical interactions between solid particles. This innovative approach makes it possible to predict how these dusts would affect the energy balance of the global climate and the planet.

Earth’s atmosphere seen from space. The different colors correspond mostly to the three main layers. The lower one, yellow and orange, is the troposphere. The pink and whitish one, in the center, is the stratosphere. The one above, in blue, is the upper atmosphere. (Photo: NASA / Expedition 23 crew)

Until now, the most contemplated method in aerosol injection strategies into the stratosphere has been the dispersion of sulfur dioxide (SO2) to increase the layer of stratospheric aerosols and the reflection of solar radiation, and thus cool the Earth. However, this study proposes an alternative method by emitting ultrafine particles of other materials. “The results indicate that diamond dust could be significantly more effective than other aerosols previously proposed for solar geoengineering, such as sulfuric acid aerosols,” notes Vattioni.

The high reflectivity for sunlight and low chemical reactivity of diamonds in stratospheric environmental conditions would make them ideal candidates for this purpose. According to Gabriel Chiodo, the great advantage of these materials is that they almost do not absorb infrared radiation and, in this way, they would not heat the stratosphere. Therefore, they would not lead to the alterations in stratospheric circulation and other side effects (such as increased water vapor concentrations in the stratosphere) that are predicted by the most common geoengineering method, sulfuric acid aerosols.

The results indicate that diamond dust could be more effective than other proposed sprays. However, uncertainties remain about its practical feasibility, especially in terms of preventing particles from sticking to each other. This adhesion would reduce its reflective capacity and accelerate its sedimentation, thus reducing its effectiveness in cooling the climate.

The study estimates that dispersing approximately one million tons of diamond dust per year could partially counteract global warming. However, the associated costs raise questions about its economic viability.

The research team emphasizes that this technique does not address the fundamental causes of global warming. “Climate intervention with diamond dust could buy time, but it is not a definitive solution,” emphasizes Chiodo. The study also highlights the possible risks and side effects of dispersing diamond dust in the atmosphere, including changes in precipitation patterns. Therefore, the authors invite the scientific community to conduct more research on these aspects before considering any large-scale implementation.

The study is titled “Microphysical Interactions Determine the Effectiveness of Solar Radiation Modification via Stratospheric Solid Particle Injection.” And it has been published in the academic journal Geophysical Research Letters. (Source: Gabriel Chiodo / IGEO / CSIC)