David Galadí-Enríquez
Lecturer in the Department of Physics at the University of Cordoba
The uncontrolled growth of artificial satellite fleets in low orbit means that all these objects, when they re-enter (and they all eventually do), vaporise and inject large amounts of metals into the atmosphere. These metals have either never been in the atmosphere (such as lithium, the subject of the article) or are there as a result of the natural flow of meteors, but in much smaller quantities than those induced by this human activity.
The article estimates that a single re-entry such as the one studied in this article adds almost 400 times the amount of lithium that falls naturally from space in a whole day to the atmosphere.
The article itself acknowledges that the anthropogenic accumulation of metals in the upper atmosphere has cumulative effects with potentially significant climatic consequences, and that clarifying the uncertainties involved requires observations and climatic and chemical modeling.
The relevant point is that all the studies needed to assess the climate impact of megaconstellations are being offloaded onto the scientific community without providing additional resources for this purpose, and that polluting companies can do so without being required, until now, to make even the slightest effort related to the consequences of their activities.
As in the case of classic light pollution (caused by ground lighting), satellite megaconstellations have an impact on astronomical observation, but their consequences go beyond that. Just as classic light pollution has effects on ecosystems and human health, the unlimited growth of satellite megaconstellations affects the global climate in ways that are not yet clear, via re-entries. In addition, this proliferation congests low Earth orbit and increases the risks to its use by increasing the probability of collisions with active or inactive objects (space debris).