Piffle.
There's no demonstrated correlation between polar reversal and past major extinctions.
( Dr. Shambolic je suis charlie, Fri 2 Dec 2011, 11:50, 3 replies)

good use of the word piffle.
( Ya What Skiddlyboop, Fri 2 Dec 2011, 12:20, closed)

I toyed with "poppycock" but I thought that was overstating it a trifle.

( Dr. Shambolic je suis charlie, Fri 2 Dec 2011, 12:31, closed)

On Stilts
You could safely use poppycock without it being to exaggerated so long as you refrained from throwing in the stilts. That would be too much.
(justin(e), Fri 2 Dec 2011, 12:55, closed)

It took me a while to see it....
www.thisiskent.co.uk/beat-walk-streets/story-11982613-detail/story.html
(dchurch bah, Sun 4 Dec 2011, 11:05, closed)

Quite
The frequency of polar reversals is far greater than that of what are considered to be major extinctions.
(rockdoctor, Fri 2 Dec 2011, 13:24, closed)

^This^
Even allowing that an increase of solar radiation would cause an increase of cancers, these would only be a threat to the creatures that develop them. As long as those creatures manage to reproduce before dying - and there's precious little reason to suppose that any tumours would be a particular impediment to that - the species would be just dandy. Hence no extinctions.
( Enzyme is powered by sunlight, Fri 2 Dec 2011, 16:27, closed)