all good Derty and your view of the radiation belts really...

all good Derty and your view of the radiation belts really matches mine which is pretty standard,as you say only very large eruptions have much chance of penetration so efficient are our shields.
You may know that I have had an interest in the warming claims for many years from not only the research but also the business angle which politicians fail to understand miserably .
What has occurred to me looking at the results of this particular effort by NASA is the blanketing effect of Co2 etc,

The opinion has been well documented that warming precedes any rise of Co2 and the way it is released (remember it has always been here),question is are the researchers looking in the wrong direction ?

It is assumed that warming is the result of a few more ppm in the atmosphere but look at what you have rightly said,the heat is reflected.

Now we know (I think) that there has been no warming for over 17 years, in fact many places on the globe have experienced lower than average in the last years,taking your understanding a bit further perhaps the little bit of CO2 extra is blocking a tad more solar radiation and not leading to warming at all but rather a cooling of the planet.
We may well need to take another look at CO2 but for completely opposite reasons.
It is an old saying "we cannot see the woods for the trees"
much to learn yet.

Going now to your question as to what this research means for the Green House effect Derty my belief is that everything is interactive and the smallest tipping points can often come from an unexpected direction,hope this helps.