Much more information here.
If you can't get the books, and aren't willing to wade through the web site, here's my elevator talk summary:
About every 12,000 years the Earth experiences a global catastrophe. From the geological record some of the elements of this catastrophe are (i) An increase of impact events, (ii) Massive flooding, deluge and/or great waves, (iii) rare isotopes in the flood/wave deposits.It is unclear what is causing the confluence of these three seemingly unrelated factors. One model that is gaining support is the motion of the solar system in its orbit around the Milky Way Galaxy crosses the galactic current sheet. The galactic current sheet gathers gasses, dust and larger chunks, like a ‘Swiffer Duster’.
This increases the odds of an impact with a big chunk! (i) an increase in impact events, and some of these events can cause (ii) great waves, with the resulting far inland mega tsunami deposits.
More subtly, blanketing the inner solar system with dust is much like a cloudy night keeping the land warmer than a clear night. Only unlike the Sun, the land isn’t trying to pour massive amounts of freshly generated heat into the universe! The Sun’s heat no longer has a clear path to escape. This causes reflected radiation heating of the Sun’s surface.
Extra heat has to go somewhere. The result is being called a ‘micronova’ when the sun ‘boils over’. This is not a full-up star destroying nova, but a violent shedding of the Sun’s outer layer. This blows the dust out of the center of the solar system, and pretty much incinerates the Sun facing side of the earth. The surfaces of the oceans facing the Sun at that moment flash into an amazingly large amount of water is vapor saturating the atmosphere, where it chills to ice and water, which falls back to Earth causing (ii) Massive flooding, deluge, and where it falls as snow, an instant ice age, explaining how it is possible for a mastodon with a mouth full of summer plants can be frozen where it stands.
That leaves (iii) rare isotopes in the flood/wave deposits. Those are classically explained as remains of nearby supernova. The problem is that even the closest nearby supernovae are so far away that the isotopes would have long since decayed away. The event that generated them wasn’t hundreds of light years away, it was only eight light minutes away!
Half the Earth broiled and saturated with solar x-rays, the other half subject to blizzards, and floods. That’s not even the bad news.
The bad news is the associated induced currents will wipe out power grids and fry semiconductors world-wide.
No internet, no lights, no pumped water, no computer controlled generators, inverters, no cars, no trucks. No re-supply of grocery stores. No way for any government to give orders farther than a shout can carry. Civilization collapses, all civilization, not just technological civilization.
This Solar disaster happens about every 12,000 years… …the last one, the Gothenburg event, was about 12,000 years ago.