Rocket soot to drive 42% of space sector climate impact by 2029

Scientists from University College London have warned that satellite megaconstellation launches are causing significant pollution to Earth's upper atmosphere, with emissions on track to account for 42 percent of the space sector's climate impact by the end of the decade. The pollution comes primarily from black carbon or soot released during rocket launches carrying satellites for companies like SpaceX, which has launched nearly 12,000 satellites since 2019. Research published in the journal Earth's Future found that this high-altitude pollution lasts much longer than ground-level emissions, causing a 540 times greater environmental impact. The study estimates that by 2029, approximately 870 metric tons of soot could be deposited in the atmosphere annually from these launches, up from 35 percent of space sector climate impact in 2020. Lead researcher Eloise Marais from University College London described the situation as "a small-scale, unregulated geoengineering experiment that could have many unintended and serious environmental consequences." While the soot could potentially cause mild cooling effects by blocking sunlight, Marais cautioned that any such climate intervention carries unknown risks and should not be viewed as a solution to global warming. The researchers emphasize that current impacts remain relatively small, providing a window for regulatory action before the problem becomes more severe and difficult to reverse. In a separate but related development, researchers from the University of Massachusetts Amherst found that wood burning is reintroducing lead into the air of communities across the United States. The study found clear associations between wood burning particles and lead concentrations in the atmosphere, with the lead likely absorbed by trees from soil before being released during combustion. Although lead levels remain below legal limits, researchers note that any exposure to the neurotoxic metal, which was banned from petrol over 25 years ago, poses health risks, particularly in neighborhoods where wood burning is common.