The new activity is dominated by Supervolcanos. A Supervolcano qualifies to be called a "Supervolcano" because it is directly implicated in a previous mass extinction. That's why they label it a Supervolcano.
If you're new to all of this or what you do know is mainly from public television and documentaries, you'd be astonished to know just how many extinction cycles have been revealed over the past two decades. You'd probably think that there weren't enough extinction cycles to go around that every little supervolcano could get the credit for one all on it's own. You'd be wrong. The history of the planet is very, very catastrophic. As more and more ash layers have been identified, more and more volcanos have been identified as having blown at the same time. So we have ash layers/mass extinctions linked to Krakatoa, one linked to Toba, several to Yellowstone, one for Vanuatu ... etc. you get the idea. There's plenty of catastrophic cycles to go around to peg on 'em all.
You're thinking, wait a second Tex, if the history of this planet is so catastrophic then how come I've never known an interruption in cappuccino service in my entire life? It's because you have lived during a very odd lull, a quiescent period in which our entire civilization has sprouted up unmolested during an interglacial. There's nothing normal about the past 1000 years. We can make the anthromorphic argument and say had there been no such break in the action, I would not be writing this blog for you - and you'd likely be right.
Every single period of increased volcanism has accompanied changes in the magnetic field the Earth shares with the Sun. Every single period correlates to a corresponding change in the magnetosphere. The two things are yoked at the hip like Siamese twins.
You should consider that the historic evidence indicates that long periods of convalescence like the earth has gone through in the last twelve millennia seem to always be terminated with savage fury as things return to normal. Because we have been living during such a placid era, it is to be expected the nadir of this window, which approaches in December 2012, will close with sharp and sudden resurgence in the earth's "normal" routine.
Think of our society as an anthill that has been constructed in the center of an artillery reservation during the off-season. It's a very apt analogy. All the ants have ever known is a placid, fertile and uninterrupted peace, surrounded by sunlight, butterflies and abundant resources. Unfortunately, their anthill is marked as dead center for artillery calibration and the summer firing exercises are about to begin.