Rocket launches are turning the upper atmosphere into an accidental climate experiment

A new study from University College London (UCL) reveals rocket launches from satellite megaconstellations are rapidly increasing pollution in the upper atmosphere, potentially becoming the dominant source of space-sector climate impact by 2029. Researchers analyzed emissions from 2020 to 2022 and projected growth through the decade, focusing on black carbon (soot) released during launches and satellite reentry. Unlike surface soot, which dissipates quickly, rocket soot lingers for years in the upper atmosphere, where it is 540 times more effective at altering climate. The study, published in *Earth’s Future*, warns that soot from rockets slightly cools Earth’s surface by blocking sunlight but warms the upper atmosphere, creating unintended environmental consequences. Lead author Connor Barker called rocket launches a 'unique source of pollution' that disrupts one of Earth’s last pristine atmospheric layers. While surface cooling might seem beneficial, researchers caution against treating it as a solution, emphasizing the need for early regulation before impacts worsen. The rise of megaconstellations—including SpaceX’s Starlink (over 10,000 satellites in orbit), Amazon’s Project Kuiper, and China’s Guowang—drives the issue, as frequent launches and satellite replacements accelerate pollution. UCL noted annual rocket launches nearly tripled in recent years, with no current framework to monitor or mitigate atmospheric effects. Project lead Eloise Marais described the situation as an 'unregulated geoengineering experiment,' urging swift action before the problem becomes irreversible. The study highlights the lack of oversight in space industry emissions, despite growing concerns about long-term atmospheric changes. Researchers stress that current pollution levels are still small, offering a window to implement safeguards before irreversible damage occurs. Without intervention, the unchecked growth of satellite networks could exacerbate climate disruptions in ways that are difficult to predict or reverse.