10Be evidence for the MatuyamaâBrunhes geomagnetic reversal in the EPICA Dome C ice core

10Be evidence for the Matuyama-Brunhes geomagnetic reversal in the EPICA Dome C ice core slipped by me when it was published last year (Nature 444, 82-84 (2 November 2006)). If they are correct, then its nice for the ice core folk because it provides an absolute tie-point into the marine records. Its also interesting for the rest of us, because of the potential connection to the clouds-solar stuff: together with the 41 kyr "event" it provides some test as to whether cosmis rays do affect climate.

If you look at cosmocr*pology, you'll notice (somewhat buried in the S "paper") some handwaving to try to explain why the 41kyr event is the wrong sort of cosmic rays. But that needs further consideration.

If they are correct... I said above. And they do admit to some data problems: lots of spikes in the Be record which they remove by median-ing instead of mean-ing. I'm not sure. Its not a stunning peak, but I'll have to leave it to the experts to judge. Oh, I should have added: of course the peak is exactly where it *should* be, based on the previous independent time scale, which is definitely supporting evidence.

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I think I heard Eric Wolff say last year that they are hoping to go past 1myr at some point in the next few years. He also said that the new age models are independent of Milankovitch assumptions, before admitting under ferocious questioning (or at least a little sqeak from me at the end) that there will still be tie points to the ocean stacks. Sigh.

I am a lay person so please bear with me. The one article that I have been able to find on the "do cosmic rays affect climate" question is:

On possible drivers of Sun-induced climate changes

We tested the validity of two current hypotheses on the dependence of climate change on solar activity. One of them states that variations in the tropospheric temperature are caused directly by changes of the solar radiance (total or spectral). The other suggests that cosmic ray (CR) fluctuations, caused by the solar/heliospheric modulation, affect the climate via cloud formation. Confronting these hypotheses with seven different sets of the global/hemispheric temperature reconstructions for the last 400 years, we found that the former mechanism is in general more prominent than the latter. Therefore, we can conclude that in so far as the Sun-climate connection is concerned tropospheric temperatures are more likely affected by variations in the UV radiation flux rather than by those in the CR flux.

That is the best I've been able to do with my limited resources. I'd love to hear your thoughts.

Stoat: I have no idea what you're talking about! (Doubtless a framing problem.)

BrendaV: Thanks for the link to the article. It reinforces my prejudices, which is always nice.

By Mark Hadfield (not verified) on 16 Apr 2007 #permalink