How Climate Change is Quietly Reshaping Low Earth Orbit—and Why It Matters for Satellites
When we think about climate change, we often focus on its effects on Earth—rising sea levels, extreme weather, and melting ice caps. But a groundbreaking study published in Nature Sustainability(Parker et al., 2025) reveals a surprising and critical consequence of climate change that extends far beyond our planet’s surface: the shrinking of Earth’s upper atmosphere, which is directly impacting the sustainability of low Earth orbit (LEO), where most satellites operate.
What’s Happening in the Upper Atmosphere?
The thermosphere, a layer of the atmosphere that extends into LEO (200–1,000 km above Earth), is cooling and contracting due to the buildup of greenhouse gases (GHGs) like carbon dioxide (CO2). While GHGs trap heat in the lower atmosphere (causing global warming), they have the opposite effect in the upper atmosphere. Here, CO2 absorbs and radiates heat away into space, leading to a cooling effect. Over time, this cooling causes the thermosphere to shrink, reducing the density of the atmosphere at satellite altitudes.This might sound like a good thing—less atmospheric drag means satellites can stay in orbit longer. But there’s a catch: this same reduction in drag also allows space debris to remain in orbit for much longer, increasing the risk of collisions and the potential for a catastrophic chain reaction known as theKessler Syndrome.
The Growing Threat of Space Debris
Space debris—fragments of defunct satellites, rocket stages, and other objects—has been a growing concern for decades. In LEO, atmospheric drag naturally slows down debris, causing it to re-enter and burn up in Earth’s atmosphere. However, as the thermosphere contracts and density decreases, this natural cleanup process slows dramatically. Debris that would have deorbited in a few years could now remain in orbit for decades or even centuries.This creates a dangerous situation. With more debris lingering in orbit, the likelihood of collisions increases. Each collision generates even more debris, which can trigger a cascading effect where the orbital environment becomes so cluttered that it’s no longer safe for satellites to operate. This is the essence of the Kessler Syndrome, a scenario that could render parts of LEO unusable for future generations.
How Bad Could It Get?
The study used climate models to project the effects of different CO2 emission scenarios on the thermosphere and LEO’s carrying capacity—the maximum number of satellites that can safely operate without triggering runaway debris growth. The results are alarming:
By 2100, the satellite carrying capacity of LEO could decrease by 50–66% under high-emission scenarios.
The most significant reductions in capacity are expected at higher altitudes (above 400 km), where debris already takes longer to deorbit.
Even under moderate emission scenarios, the carrying capacity of LEO is projected to shrink significantly, making it harder to sustain the growing number of satellites being launched.
Why This Matters for the Satellite Industry
LEO is the backbone of modern satellite operations, supporting everything from global communications and navigation to weather forecasting and Earth observation. The rapid expansion of satellite constellations, such as SpaceX’s Starlink and Amazon’s Project Kuiper, has already increased the density of objects in orbit. If we don’t address the combined challenges of space debris and climate-driven changes to the thermosphere, we risk overloading this critical region of space.For satellite operators, this means more frequent collision avoidance maneuvers, higher insurance costs, and stricter regulations on satellite deorbiting and debris mitigation. The U.S. Federal Communications Commission (FCC) has already reduced the recommended deorbit timeline for defunct satellites from 25 years to just 5 years, but these measures may not be enough if the thermosphere continues to shrink.
A Call for Unified Action
The study underscores the need for a unified approach to tackle two interconnected challenges: climate change and space sustainability. Reducing GHG emissions won’t just benefit life on Earth—it will also help preserve the orbital environment by slowing the contraction of the thermosphere. At the same time, the satellite industry must adopt more aggressive debris mitigation strategies, such as active debris removal, improved tracking systems, and better coordination between operators.As the authors of the study point out, “Climate change and orbital debris accumulation are two pressing issues of inextricable global concern requiring unified action.” The future of LEO—and the countless services it supports—depends on our ability to address these challenges together.
This blog post is based on the findings of Parker et al. (2025) in Nature Sustainability. You can read the full study here:https://doi.org/10.1038/s41893-025-01512-0.