No, Smithsonian Magazine, Climate Change Is Not the Main Driver of Satellite Collision Risk—The Sun Is
10 hours ago Anthony Watts
A recent article from Smithsonian Magazine (SM) titled “Climate Change Might Increase Satellite Collisions, Limiting How Many Can Safely Orbit Earth, Study Finds” claims that human-induced climate change is causing the upper atmosphere to contract, reducing drag on satellites and space debris, which could lead to more collisions. This is misleading if not outright false. Multiple studies show the dominant factor influencing the density and temperature of the upper atmosphere—where some satellites orbit—is solar activity, not carbon dioxide emissions. Data from decades of space research confirm that variations in solar radiation, particularly changes in ultraviolet (UV) output and solar wind, have far greater impacts on atmospheric density than any CO₂-driven effects.
The study, referenced by the SM article, is summarized as: “The thermosphere, which begins around 50 miles (80 kilometers) above Earth’s surface, is contracting. This is because as greenhouse gases like carbon dioxide and methane accumulate in the lower atmosphere, they radiate heat into space and cause the upper atmosphere to cool and shrink.” This claim exaggerates the role of human greenhouse gas emissions while ignoring the well-documented influence of solar variability.
The thermosphere, seen in the graphic from The Canadian Space Agency below, is primarily heated by the Sun’s intense ultraviolet radiation, and its temperature and density fluctuate significantly in response to the 11-year solar cycle. When solar activity is high, the thermosphere expands, increasing drag on satellites and space debris. Conversely, during solar minima, the thermosphere contracts. These natural solar-driven variations completely overshadow any potential effect from anthropogenic CO₂.
https://wattsupwiththat.com/2025/03/17/no-smithsonian-magazine-climate-change-is-not-the-main-driver-of-satellite-collision-risk-the-sun-is/
