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.

Satellite vs. Terrestrial: Complementary or Competitive?

The world is more connected than ever, and the demand for reliable, high-speed internet continues to grow. From urban centers to the most remote corners of the globe, connectivity is no longer a luxury—it’s a necessity. Two key players in this space, satellite internet and terrestrial networks, are often portrayed as competitors. Add to this the buzz around "direct-to-device" satellite connectivity, and the conversation becomes even more muddled.But is this competition real? Or are these technologies better viewed as complementary solutions? And what about the hype surrounding direct-to-device connectivity—are we expecting too much, too soon? Let’s explore these questions and level-set expectations while examining how satellite and terrestrial networks can work together to meet the world’s connectivity needs.

The Promise and Challenges of Satellite Internet

Satellite internet has been making headlines, especially with the rise of Low Earth Orbit (LEO) constellations like SpaceX’s Starlink and OneWeb. These systems promise to bring high-speed internet to places where traditional infrastructure is impractical or too expensive to build. For rural communities, remote industries, and even disaster-stricken areas, satellite internet offers a lifeline.What makes satellite internet stand out?
Its biggest strength is global coverage. Satellites can reach areas that terrestrial networks simply can’t, such as remote villages, ships at sea, or planes in the sky. Additionally, satellite systems are resilient—they’re less vulnerable to natural disasters or infrastructure failures, making them a reliable option in emergencies.But satellite internet isn’t without its challenges. Latency, while improving with LEO satellites, is still higher than terrestrial networks, which can be a dealbreaker for applications like gaming or real-time financial transactions. Cost is another factor. Deploying and maintaining satellite constellations is expensive, and that cost often trickles down to consumers, making it less accessible for widespread use.

Terrestrial Networks: The Backbone of Connectivity

Terrestrial networks, on the other hand, dominate urban and suburban areas. These systems rely on infrastructure like fiber-optic cables, cell towers, and microwave links to deliver high-speed, low-latency internet. For densely populated regions, terrestrial networks are the go-to solution.Their strengths are clear: low latency, high speeds, and cost-effectiveness in areas with existing infrastructure. Fiber-optic networks, in particular, offer unmatched performance for bandwidth-intensive applications like streaming and video conferencing.However, terrestrial networks have their own limitations. Building infrastructure in remote or rural areas is often cost-prohibitive, leaving many regions without reliable connectivity. Additionally, terrestrial systems are vulnerable to natural disasters—hurricanes, earthquakes, or floods can knock out service for days or even weeks.

Direct-to-Device: Overhyped or the Next Big Thing?

One of the most talked-about developments in satellite communications is direct-to-device connectivity. The idea of connecting your smartphone directly to a satellite without additional hardware sounds revolutionary. Companies like AST SpaceMobile and Lynk are working to make this a reality, and the potential use cases—emergency communications, rural connectivity—are exciting.But let’s be honest: direct-to-device connectivity has been overhyped. The technology is still in its infancy and faces significant hurdles. For one, most current smartphones aren’t equipped to communicate directly with satellites, meaning hardware upgrades or specialized devices may be required. Spectrum allocation is another challenge—ensuring satellites and terrestrial networks can share spectrum without interference is no small feat. And even if these hurdles are overcome, direct-to-device connections are unlikely to match the speed and reliability of terrestrial networks anytime soon.While it’s an exciting development, direct-to-device connectivity is not a replacement for terrestrial or traditional satellite networks. Instead, it’s a complementary solution for specific scenarios, like emergency communications in remote areas.

Competition or Collaboration?

The narrative of competition between satellite and terrestrial networks often overshadows the reality: these systems are increasingly complementary. Yes, there’s competition in certain markets—satellite providers like Starlink are disrupting traditional telecom markets by offering broadband services directly to consumers, particularly in underserved areas. Meanwhile, terrestrial networks, especially with the rollout of 5G, continue to dominate urban markets with faster speeds and lower costs.But the real potential lies in collaboration. Hybrid networks, which combine the global coverage of satellites with the speed and reliability of terrestrial systems, are already emerging as a powerful solution. For example, industries like aviation and maritime primarily rely on satellite systems for connectivity in remote areas, such as over oceans or during flights. However, terrestrial networks play a role when these operations are near or within populated areas, such as ports, coastal regions, or airports, where high-bandwidth terrestrial infrastructure is available.

The Future of Connectivity

Looking ahead, the future of global connectivity lies in the convergence of satellite and terrestrial networks. As technologies like 5G and beyond continue to evolve, the integration of these systems will become even more critical. Hybrid models, such as Space-Air-Ground Integrated Networks (SAGIN), are already being developed to provide seamless communication across land, sea, and air.Emerging technologies like artificial intelligence (AI) and machine learning (ML) will further optimize these hybrid networks, enabling efficient spectrum management, predictive maintenance, and autonomous operations. Additionally, advancements in satellite miniaturization and reusable launch technologies are driving down costs, making satellite internet more accessible to consumers.

Final Thoughts

Satellite internet and terrestrial networks each have unique strengths that make them indispensable in the quest for global connectivity. While competition exists in certain markets, their true potential lies in collaboration. By integrating these systems, we can create a world where everyone, regardless of location, has access to reliable, high-speed internet.As for direct-to-device connectivity, it’s an exciting development, but it’s not the silver bullet some make it out to be. It’s a niche solution that will complement, not replace, existing networks. By leveling expectations and focusing on the complementary nature of satellite and terrestrial systems, we can better understand how to leverage their strengths to build a more connected future.The question isn’t whether satellite and terrestrial networks are complementary or competitive—it’s how we can use both to meet the growing demand for connectivity in a way that’s sustainable, reliable, and accessible for all.