It seems solar flares are in the news as Paul La Violette, in the journal Radiocarbon (June 2011, 53:2 page 303-323) claims a super solar flare was responsible for the Pleistocene extinctions – or those that occurred at the onset of the Younger Dryas event. He says that there was an abrupt rise in atmospheric radiocarbon concentrations in the Cariaco Basin varve record (from lake sediments) at 12.837 years BP (the beginning of the Younger Dryas event). In other words, he is suggesting that as there is no crater the cometary impact theory for the advent of the Younger Dryas is invalid so another reason must be found. As he has for many years advocated super novae as the agency of destruction this is something of a new twist – a super dooper solar flare. Do they happen? Again, he assumes such a flare is capable of sending death dealing radiation to the surface of the earth and conveniently ignores a number of strange geological anomalies. La Violetter also claims there was a prominent acidity spike in Greenland ice cores at the same point in time and a rapid rise in Beryllium 10 deposition. It is also associated with elevation ammonium ion concentrations which La Violetter claims is attributable to global landscape fires – but see Mike Baillie, New Light on the Black Death for an association of ammonium spikes with meteoric/ cometary intrusions. La Violette, on the other hand, goes so far as to say the Younger Dryas onset had no connection with an impact event, saying the nitrate ion signal was not strong enough. There are problems, it would seem, in both hypothesis.
Bill Napier has said recently that there was a seven per cent increase in C14 in the year following the Tunguska event (quoting Cowan, 1977) and Brown and Hughes (also 1977) explained it by the production of energetic neutrinos in the incoming fireball which converted atmospheric nitrogen to C14. If the Younger Dryas event involved multiple Tunguska like objects, as theorised by Napier, there would have been large fluctuations in C14 at the time – and there was. So, do C14 plateaus or injections require a solar source such as a flare as hypothesized by La Violette?