[R]educing our emissions might just save humanity from a pre-emptive alien attack, scientists claim.
Watching from afar, extraterrestrial beings might view changes in Earth’s atmosphere as symptomatic of a civilisation growing out of control – and take drastic action to keep us from becoming a more serious threat, the researchers explain.
This highly speculative scenario is one of several described by a Nasa-affiliated scientist and colleagues at Pennsylvania State University that, while considered unlikely, they say could play out were humans and alien life to make contact at some point in the future.
The paper says:
ETI [Extraterrestrial Intelligence] could seek our harm if they believe that we are a threat to other civilizations.
The thought of humanity being a threat to other civilizations may seem implausible given the likelihood of our technological inferiority relative to other civilizations. However, this inferiority may be a temporary phenomenon. Perhaps ETI observe our rapid and destructive
expansion on Earth and become concerned of our civilizational trajectory. … [P]erhaps ETI believe that rapid expansion is threatening on a galactic scale. Rapidly (maximally) expansive civilizations may have a tendency to destroy other civilizations in the process, just as humanity has already destroyed many species on Earth. ETI that place intrinsic value on civilizations may ideally wish that our civilization changes its ways, so we can survive along with all the other civilizations. But if ETI doubt that our course can be changed, then they may seek to preemptively destroy our civilization in order to protect other civilizations from us. A preemptive strike would be particularly likely in the early phases of our expansion because a civilization may become increasingly difficult to destroy as it continues to expand. Humanity may just now be entering the period in which its rapid civilizational expansion could be detected by an ETI because our expansion is changing the composition of Earth’s atmosphere (e.g. via greenhouse gas emissions), which therefore changes the spectral signature of Earth. While it is difficult to estimate the likelihood of this scenario, it should at a minimum give us pause as we evaluate our expansive tendencies.
It is worth noting that there is some precedent for harmful universalism within humanity. This precedent is most apparent within universalist ethics that place intrinsic value on ecosystems. Human civilization affects ecosystems so strongly that some ecologists now often refer to this epoch of Earth’s history as the anthropocene. If one’s goal is to maximize ecosystem flourishing, then perhaps it would be better if humanity did not exist, or at least if it existed in significantly reduced form. Indeed, there are some humans who have advanced precisely this argument. If it is possible for at least some humans to advocate harm to their owncivilization by drawing upon universalist ethical principles, then it is at a minimum plausible that ETI could advocate harm to humanity following similar principles.