The thing that caught my imagination was that with the Sun's magnetic
field contracted, the Earth is getting hit with much more cosmic rays
from exploding stars and black holes in deep space.

If you've ever watched a cloud chamber with a mildly radioactive
element in it, you've seen the 'contrails' charged subatomic particles
leave. It's a classic way of demonstrating natural radioactivity and
atomic fission.

Cosmic rays are individual protons or heavy nuclei that can hit the
upper atmosphere with the energy of a pistol bullet. A collision with
an atmospheric molecule creates a shower of subatomic particles that
can reach the surface and can be detected photometrically.
Apparently, these particle showers also cause clouds as in the cloud
chamber - or at least condensation nuclei which later cause clouds. Or
perhaps in some cases, punch holes in them. http://media.mgbg.com/wkrg/photos/weather/hole06.JPG