The Surprising Link Between CO2 Levels and Satellite Collisions

 

Climate change isn’t just warming the planet—it’s reshaping space.

As greenhouse gases trap heat in the lower atmosphere, the upper atmosphere cools and contracts, reducing the drag that naturally pulls old satellites back to Earth. With satellites lingering longer in orbit, the risk of collisions and space debris skyrockets, threatening the future of satellite communications, weather forecasting, and navigation.

Rising Satellite Numbers and a Changing Atmosphere

More than 8,000 satellites currently orbit Earth at altitudes between 300 and 1,000 km, within the thermosphere — our planet’s upper atmosphere. While space weather events like solar flares and coronal mass ejections can briefly alter the density of this region, researchers at the University of Birmingham suggest that climate change is driving a much longer-term shift.

Greenhouse gases (GHGs) play a key role in this change. In the lower atmosphere, these gases trap heat, warming the planet. However, they also transfer heat away from the upper atmosphere, causing it to cool and contract. As a result, satellites are left in areas where the atmosphere is thinner.

Less Atmospheric Drag, More Space Junk

This reduced atmospheric density means less drag on satellites, which significantly affects their lifespan. Normally, atmospheric friction gradually slows satellites, causing them to fall back to Earth over time. Without enough drag, they remain in orbit longer than intended.

This extended stay increases the risk of satellite collisions, leading to more space debris and making it harder to launch new satellites safely.

A New Threat to Space Sustainability

The findings, published today (March 10) in Nature Sustainability, provide a clear link between ground-level sustainability and space sustainability.

Lead researcher Matthew Brown, from the SERENE research group, said: “Often we think only about the ground-, or sea-level impacts of climate change, but this research demonstrates that the impacts will reach as high as space.

“The numbers of satellites in low Earth orbit is rapidly expanding and we rely heavily on them for communications, Earth observation, weather forecasting and navigation. For this reason, we need to take the long-term sustainability of space very seriously.”

The Growing Risk of Kessler Syndrome

Dr. Brown added: “Discussions are already underway about how many satellites can be put into space at any one time, as more and more instruments are being launched into low Earth orbit. Without checking this proliferation, we are in danger of entering a ‘Kessler syndrome’, where a chain reaction of collisions causes space to become unusable.

“While technology can help these objects avoid collision, recognising the influence that the Earth’s natural environment has on our ability to operate in space is becoming increasingly important. A coordinated approach to reducing greenhouse gas emissions would ensure we can prevent the exploitation of the thermosphere and protect it for future generations.”

website: popularscientist.com

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