Two physicists from the University of California Santa Barbara examined possible methods for averting the devastation that would be caused should a 10 km. asteroid impact the Earth, à la the recent Netflix original film Don’t Look Up.
Though the subject of the movie is a hypothetical asteroid on course to impact earth in six months' time, many consider it to be an analogy to the potential consequences Earth’s inhabitants will face if we continue to take minimal action in regard to climate change.
Prof. Philip Lubin and Alex Cohen, researchers at UC Santa Barbara, demonstrate in their study, which is awaiting peer-review, that technological developments may provide a reason to remain optimistic about such hypothetical asteroid-induced destruction. “We show that humanity has crossed a technological threshold to prevent us from ‘going the way of the dinosaurs,” they explained. The study is post-moderation but has yet to be peer-reviewed.
That is not to say that impact from such a large asteroid would be negligible. The authors describe just how powerful the effect would be: "A threat of this magnitude hitting the Earth at a closing speed of 40 km/s would have an impact energy of roughly 300 Teratons TNT, or about 40 thousand times larger than the current combined nuclear arsenal of the entire world. This is similar in energy to the KT extinction event that killed the dinosaurs some 66 million years ago."
When foreign bodies enter Earth's atmosphere at a particular speed, the atmospheric temperature rises accordingly. The study explains that in the case of a 10 km object traveling at 40 km/s, we can expect an approximate temperature rise of 300 degrees Celsius, well beyond the threshold for continued life on Earth as we know it. The general consensus among climate scientists is that a rise in atmospheric temperature of just 2 degrees Celsius would increase the frequency of events such as floods, droughts and heatwaves. Three hundred degrees would be catastrophic.
Various methods of interception were examined in the study, including the PI method "Pulverize It," in which an array of penetrators inject detonation energy into the asteroid to break it into smaller pieces.
Earth's atmosphere provides a certain degree of protection against small asteroids, and larger pieces would be redirected by the force to circumvent the Earth entirely. While this method was favored as the most effective of those examined, it would not be without complications.
The Partial Nuclear Test Ban Treaty prohibits all test detonations of nuclear weapons except for those conducted underground - meaning such tests could not be conducted in outer space at this time.
Another strategy could be to attempt to drill a hole into the asteroid and then detonate a nuclear bomb inside of it, though this is a less likely solution as it would require a great deal more of TNT than currently exists within Earth's nuclear arsenal. It would also require testing not currently permitted under the Partial Nuclear Test Ban Treaty.
Their findings are fascinating and there is certainly a degree of comfort that can be taken in knowing such possible situations are being considered and prepared for by those who best understand them; indeed the authors are not alone in their research - NASA established the Planetary Defense Coordination Office "responsible for detecting “potentially hazardous objects” such as asteroids and comets, and working on technologies that could deflect them off an impact course with Earth" in 2016.
However, it's crucial to not get swept up in the excitement of such hypotheticals. The much more dire and imminent threat of climate change is one that 97% of scientists agree is already well underway, and the point of Don't Look Up was to highlight what happens when we ignore scientific consensus. What good will preventing impact from an asteroid be if we ourselves render the earth uninhabitable?