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.
A study in the Journal of Space Research confirms that thermospheric temperature fluctuations are overwhelmingly linked to solar output, not greenhouse gases. Similarly, research in Space Weather Science demonstrates that solar activity is the primary driver of upper atmospheric density changes, affecting satellite drag far more than any CO₂-related cooling. In addition, a report in EOS shows that during a weaker-than-normal solar cycle, the thermosphere cooled and contracted more than expected. This aligns with long-term observations that solar variability dictates thermospheric behavior. NASA also credits the sun as driving the changes in the thermosphere.
While many satellites orbit Earth in the thermosphere, most Earth-orbiting satellites reside in the exosphere, such as geostationary satellites with orbits at 22,500 miles even higher than the exosphere, the outermost layer of the Earth’s atmosphere, where the atmosphere thins out and merges with outer space. So, the concerns about the thermosphere in the SM article are mostly moot, especially since many satellites that orbit in the thermosphere can boost with thrusters to a higher orbit if needed. Engineers plan for this.
The SM article also fails to consider historical data. If CO₂ were truly the primary driver of thermospheric contraction, we would expect to see a steady, predictable decline in atmospheric density as CO2 emissions have increased. Instead, we observe clear cyclical patterns that correspond with the 11 year solar cycle, not industrial CO₂ emissions. During past solar minima, such as the Dalton Minimum (1790–1830) and the Maunder Minimum (1645–1715), similar thermospheric contractions occurred—long before human activity significantly increased CO₂ levels.
By pushing a climate change-driven explanation while ignoring the Sun’s dominant role, and ignoring where most satellites orbit Earth, Smithsonian Magazine is misrepresenting what science tells us about the atmosphere and what drives change in it. Space debris is a real issue that requires attention, but CO2 neither creates space debris nor is making collision with such debris more likely. Blaming CO₂ emissions for upper-atmospheric changes is a false narrative and distracts attention from the real problem of how to handle space debris
Anthony Watts is a senior fellow for environment and climate at The Heartland Institute. Watts has been in the weather business both in front of, and behind the camera as an on-air television meteorologist since 1978, and currently does daily radio forecasts. He has created weather graphics presentation systems for television, specialized weather instrumentation, as well as co-authored peer-reviewed papers on climate issues. He operates the most viewed website in the world on climate, the award-winning website wattsupwiththat.com.
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https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022SW003330
These sat’s were parked in lower staging orbits for testing before being raised to operational orbits.
Now.. what else happened in early 2022 that caused changes to the stratosphere ?
Good point, but HT water vapor appears to mitigate the normal temperature rise associated with UV heating.
As an aside, here’s the latest HT v Askja comparison. I’ve switched to NOAA from HadCRUT5 because the MET slowed down their updates; they didn’t release January data until a few days ago. Neither shows the drop found in the UAH data. Curious.
Global sea-surface temperatures are dropping so we should soon be seeing a drop in the miracle molecule concentrations, or at least a slow in the rise.
“This claim exaggerates the role of human greenhouse gas emissions while ignoring the well-documented influence of solar variability.”
The study doesn’t ignore solar. But as it says, solar is a cycle, but GHGs accumulate. Here is their plot of how that works out:
The solar cycle varies density by about 10%, but GHG accumulation reduces it to about 60% on SSP2-4.5.
Here is how they put it:
“The thermosphere regularly experiences expansion and contraction in response to solar activity6. Solar electromagnetic radiation cycles in intensity roughly every 11 years. The globally averaged thermospheric mass density in LEO can vary by an order of magnitude between solar minimum and maximum7. Density fluctuates more rapidly but by similar magnitudes in response to geomagnetic activity enhancements from Joule heating and energetic particle precipitation8. This space-weather-driven variation in thermospheric mass density is generally transient in nature but can severely degrade short-term satellite collision avoidance capabilities9,10. GHG-induced thermosphere contraction is of particular interest in this work because it causes secular changes in density likely to last centuries.”
Bullshit. It is a CliSciFi model result.
Of course. Only modelling can tell you about the future.
But the point is that they do consider solar variation, and they do show that in the medium term, the GHG effect will dominate.
AAAAAAha ha ha ha ha.
Climate modelling tells us absolutely nothing about the future.
They are just glorified computer games with no more relevance to the future than SimCity or any of the other myriad of similar computer games.
Really? Does the model include gazing into a crystal ball?
If models could actually tell us anything about the future, no scientists would ever say “Its Worse Than We Thought”.
Hmmm, I think I’ll create a model with these assumptions. Hey look, it proved that my assumptions are correct!
That one’s a real zinger! Spoken like a true believer. Halleluja!
Only modelling can tell you about the future.
Nonsense, Nick. Tarot cards can do it, too.
Don’t forget horrorscopes, ouija boards and clairvoyants. All better than your average climate model.
SSPs and their Nostra-dumbass prophesies are totally meaningless fantasy.
Inasmuch as we have been launching satellites since 1957, and routinely since the first Landsat in 1972, it would have been interesting to see the graphs go back farther than 2000 CE.
AAAAAha ha ha ha.
Nick:
Here is a link to the entire graph you shared. In it [Figure 1.1 “d”], the solar cycle seems to change the thermospheric density by a factor of 10 [10^-13 to 10^-14 per m^3].
https://www.nature.com/articles/s41893-025-01512-0/figures/1
Also from the Nature article
“By 2100, considering SSP5–8.5 as the worst-case scenario, a 50% reduction in capacity [of LEO satellites] is observed at solar maximum with a 66% reduction at solar minimum. In the more operationally feasible 400–1,000 km range, the worst-case emissions scenario sees a 60% capacity reduction during solar maximum and an 82% loss during solar minimum by 2100.”
But it was an interesting read: I didn’t know much about orbital issues, nor the Kessler scenario.
Just for fun I asked Google’s Gemini what the spacing is for LEO satellites. It picked the Starlink Constellation [over 7000 LEO satellites] and said typically they “can be roughly in the range of
100-150 km” apart.
Yes, you’re right. I has assumed the density ratio was relative to a base state, but apparently it is relative to a state without extra GHG.
considering SSP5–8.5 as the worst-case scenario
In modelling, the assumptions are the killers. Always challenge the validity of assumptions when evaluating models.
IF the assumptions are stated, which they rarely are.
I think that we should consider SSP5–8.5 ‘a scenario too far.’
Very interesting Nick but can you explain pls explain what curves SSP-2.5 andSSP1-44.5are t just Loka like 2 graphs i one good one doubleplus ungiod
Ah, CO2! Is there nothing that the Magic Molecule can’t do?
It can’t get the climate worriers to grow some brain cells
I’m fairly certain that I have read somewhere that CO2 warming will increase the height of the atmosphere, and cause drag on some satellites, causing them to crash back to Earth.
Honestly, parody of these fruitcakes is not possible.
Smithsonian Magazine Uff da!
This is the sort of carp I would expect to see in Scientific American. I quit that subscription and will, likewise, drop Smithsonian if they get too silly.
I quit SciAmerican years ago because of the BS, I had always loved Smithsonian…then they garbaged up, got trite-so I left also. Don’t get me going on National Geographic; it too went to crap. Sigh…all my favorites. Once.
Does nobody at Smithsonian have any responsibility for truth? Is anybody at Smithsonian accountable for putting out lies? Can any pressure be put on Smithsonian’s funding sources to force compliance with basic scientific truth? Why does the leadership at Smithsonian feel so free to put out such obvious lies? Maybe X can shine some light on these liars?
I don’t understand this either. All of the science magazines, Times, Guardian, BBC – they all just trot out things mentioning climate change the way church groups don’t question angels and god.
Talking of which, both the local parish magazines near me have climate reading groups in which each week some climate believer has selected a book or article about climate doom and the children are given it to read and discuss the following week.
Indoctrination of children that the Jesuits would be proud of.
Funny. I would think religious groups would credit God for everything.
What is conspicuously absent from the Smithsonian Magazine is an analysis of the number and type of satellites and their orbit altitudes. Many satellites will benefit from longer time in orbit and increase the amortization time for the substantial launch and replacement costs. Generally, it is the larger and more expensive satellites that will benefit from longer on-orbit time. What is important is the net effect, not arm waving about what might, could, possibly, potentially happen.
AAAAAha ha ha ha ha.
What human induce climate change.?
Only human induced change is in urban areas, and only a complete twit would think that urban warming is going to affect satellites.
If I spent an hour with Nick, I would consider one of those suicide capsules. Not that he would depress me. It would be a means to escape him.
Yes, like the sinking feeling you get arguing with any true believer in a religious cult or political group.
Everything is a manifestation of the wonders of god and the power of the carbon dioxide molecule.
There is no room for doubt with the faithful.
Of course, the “study” uses socio-economic pathway SSP5-8.5, or sociopath 8.5 as I like to call it, to grab the “we’re all gonna die!!!” headline. As we all know, except maybe climate “scientists”, sociopath 8.5 is considered highly unlikely by everyone including the high priests at the IPCC.
Not to mention the “data” is all from flawed computer games.
Doesn’t matter which SSP they use.. they are all based on junk computer games…
… hence have no more meaning than tea leaves in a cracked cup.
“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”
Is it possible that there could be positive aspects of the change?
There are almost certainly positive aspects. However, that wasn’t the purpose of the quasi-scientific study. As I remarked elsewhere, an objective study would be concerned about the net effects, not just the negative effects.
SSP5–8.5
Groan. The first thing to do when reading any such study is ctrl-f “8.5”.
The author, Margherita Bassi, uses her creative writing training and skills to produce a fine science fiction article.
In other words, if she had graduated 50 or more years ago, as many of us did, she would have been an average student. Its unfortunate she didn’t make time to take some hard science courses.
Just how much ‘Climate Change’ money are these alarmist journalists like Margherita Bassi paid, in order to perjure their souls and spread fear amongst the public with false propaganda?