Air Pollution from Satellites Via Rocket Launches and Re-Entries is Dimming the Sun by Lingering in the Upper Atmosphere: It is an Ongoing Geoengineering Experiment, Says New Paper

  

     A new paper in Earth’s Future explores the geoengineering effects of rocket launches and re-entries related specifically to satellite mega-constellations (SMCs). The main effective source of air pollution and dimming is particulate matter, specifically black carbon, or soot, from the combustion of kerosene used as propellant. Since many of these particulates are emitted above the troposphere, they can act much like small-scale geoengineering experiments. In light of that, the paper provides some important data about this source of solar dimming. Black carbon lingers much longer above the troposphere than it does in the lower atmosphere, where it drops to the ground much more quickly, resulting in a potential of 540 times the effect on climate. This amplification is due to the soot staying in the upper atmosphere for years instead of days or weeks.

     The paper focuses on the emissions of SMCs, noting its share of space sector emissions:

“Using data from rocket launches and satellite deployments between 2020 and 2022, the team projected emissions out to the end of the decade. The analysis showed that in 2020 these megaconstellations contributed about 35% to the total climate impact from the space sector and will climb to 42% by 2029.”

     The researchers note that by 2029, the amount of this particulate matter accumulating in the upper atmosphere will have similar impacts to a geoengineering experiment.

     Project lead, Professor Eloise Marais (UCL Geography) said:

“The space industry pollution is like a small-scale, unregulated geoengineering experiment that could have many unintended and serious environmental consequences. Currently the impact on the atmosphere is small, so we still have the chance to act early before it becomes a more serious issue that is harder to reverse or repair. So far there has been limited effort to effectively regulate this type of pollution.”

“The cooling effect from the reduction in sunlight that we calculate with our models may sound like a welcome change against the backdrop of global warming, but we need to be extremely cautious.”

     The researchers also noted that this is likely to be an underestimate since the data used was from 2020-2022, when there were fewer SMCs in orbit. SMCs, such as those launched by Starlink, have significantly increased the number of launches and re-entries. Starlink currently has about 12,000 satellites in orbit. They note that early estimates of an additional 65,000 satellites in orbit by 2030 are likely to be underestimated.

     Lead author Dr. Connor Barker (UCL Geography) said:

“Rocket launches are a unique source of pollution, injecting harmful chemicals directly into the upper layers of the atmosphere and contaminating Earth's last remaining relatively pristine environment. Though this soot’s impact on climate is currently much smaller than other industrial sources, its potency means we need to act before it causes irreparable harm.”

     They also analyzed the potential of SMCs to increase ozone depletion and found that the effect on ozone would likely be small, since most comes from propellants that emit chlorine, and few SMCs emit chlorine. They generally burn kerosene instead. However, it is estimated that there are enough rockets that burn fuels that emit chlorine to result in a little less than 10% of global ozone-depleting emissions. The SMCs are designed to be temporary, to burn up on re-entry, and be replaced by additional launches.

     More information is given in the paper’s conclusions about the effects of SMCs and the methodologies of the study:

“Satellite megaconstellations (SMCs) have grown rapidly since the first operational satellites were launched in 2019, to now comprise almost three-quarters of satellites in low-Earth orbit and most propellant consumed. Further rapid expansion is expected in the coming decades, leading to significant increases in launch rates to maintain megaconstellation populations and in re-entry rates as these relatively short-lived satellites reach end-of-life. Here we use an emission inventory of the major air pollutants from rocket launches and object re-entries at the dawn of the megaconstellation era (2020–2022). We evaluate the NOx emission factor used in the emission inventory against high-altitude aircraft observations from the SABRE campaign and project emissions to 2029. We implement these emissions in the GEOS-Chem model coupled to the RRTMG radiative transfer model to quantify O3 loss and radiative forcing attributable to SMCs.”

     They analyze trends in propellant consumption and the emissions of SpaceX’s Falcon 9 rockets to arrive at their predictions.

      While those critical of geoengineering often point to the possibility of unintended consequences, it is not certain that there are any as of yet or whether there will be. This study and subsequent quantification of upper atmosphere emissions should be important in determining if, and by how much, future geoengineering efforts will be successful in reducing global warming. 

 

References:

 

Research paper warns that there’s a massive experiment at work to geoengineer the Earth’s climate. Frank Landymor. Futurism. May 23, 2026. Research paper warns that there’s a massive experiment at work to geoengineer the Earth’s climate

Radiative Forcing and Ozone Depletion of a Decade of Satellite Megaconstellation Missions. Connor R. Barker, Eloise A. Marais, Eric Y. P. Tan, Sebastian D. Eastham, Glenn S. Diskin, Joshua P. DiGangi, Yonghoon Choi, Andrew W. Rollins, Eleanor Waxman, T. Paul Bui … Earth’s Future. Volume 14, Issue 5. First published: 14 May 2026. Radiative Forcing and Ozone Depletion of a Decade of Satellite Megaconstellation Missions - Barker - 2026 - Earth's Future - Wiley Online Library

Satellite launch pollution rapidly accumulating in the upper atmosphere. University College London. 14 May 2026. Satellite launch pollution rapidly accumulating in the upper atmosphere | UCL News - UCL – University College London