Replace an Asteroid with a weakening Geomagnetic field due to a Geomagnetic Excursion. Geomagnetic excursions are correlated with mass extinction in the Paleotological record. This makes sense since the Geomagnetic field shields Earth from space weather & a weakened Geomagnetic field means less protection from space weather.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018RG00...

Uh oh, we are currently going through a Geomagnetic Excursion. Why are we not doing anything about it? Why is the population at large not alerted?

https://www.sciencealert.com/new-study-shows-that-earth-s-ma...